How to maximize an exercise program for improved gains in athletic performance : a systematic analysis

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How to maximize an exercise program for improved gains in athletic performance : a systematic analysis

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How to maximize an exercise program for improved gains in athletic performance : a systematic analysis
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Quinones, Daniel J.
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Tampa, Florida
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University of South Florida
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English
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68 leaves : ill. ; 29 cm

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Honors Thesis -- USF ( FTS )

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Honors Thesis--University of South Florida, 2010. Includes bibliographical references (leaves 51-68).

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University of South Florida
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Universtity of South Florida
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All applicable rights reserved by the source institution and holding location.
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024863239 ( ALEPH )
F51-00006 ( USFLDC DOI )
f51.6 ( USFLDC Handle )

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Exercise Efficiency for Athlet i c Performance How to Maximize an Exercise Program for Improved Gains in Athletic Perfonnance: A Systemic Review Daniel J. Quinones University of South Florida Thesis Director : Marcus Kilpatrick, PhD 1

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Exercise Efficiency for Athletic Performance Introduction Elite athletes are some of the most physically gifted people on the planet. A portion of their abilities is due to genetic superiority, but many people like to think it comes from hard work put forth in training and practice Athletes can spend a significant portion of their life training to become the most physically fit and skilled people in the ir sport. Athleticism is a term sometimes used to mean athletic fitness, while others might include sport-related skill in the definition. This paper defines athleticism as the physical abilities required to excel in sports. Some sports such as golf, require a higher degree of skill than athletic fitness, yet some of the best players in the sport are still the most athletic. Athleticism is a physical quality that can be improved with practice and is one o f the most powerful factors in athletics that can give you an advantage over an opponent. Sports such as football soccer, and wrestling require so much physical aptitude that gifted athleticism is necessary for any chance of success at the elite level. The purpose of this paper is to educate athletes on the most efficient and effective methods to train in order to save them time and energy. Athletes spend countless hours in weight rooms, on running paths, and i n the pool trying to improve their fitness. Fitness can be regarded as athletic fitness, which is related to sports and performance, or fitness can be concerned with basic health. Health fitness takes into consideration qualities that lead to a produc tive, healthy lifestyle that would serve to increase the quality of life for a person. Such qualities might include cardiovascular integrity, body composition, and mental health. Athletic fitness pertains to qualities that lead to better sports performance and is the type of fitness referred to in this review. Examples of athletic fitness 2

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Exercise Efficiency for Athletic Performance include agility, speed, strength, power, and endurance. This list is neither exhaustive nor exclusive to athletic fitness but most experts would agree that many sports require at least a small degree of each of these qualities There are many other athletic qualities besides agility, speed, strength, power, and endurance that enhance athletic performance. Flexibility, resilience, and mental aptitude all contribute to performance in sport but will not be discussed in this paper. However, a review of these attributes would be beneficial to the sports and fitness communities. Basic Muscle Physiology Before attempting to understand how to make an exercise program effective it may be wise to first have a good grasp of basic muscle physiology. These concepts play a role in every aspect of athleticism and fitness and will provide a foundation for the following science. The human body has multiple organ systems to carry out processes required for l ife Two of the body systems that will be addressed most often in this review are the musculoskeletal system and the cardiovascular system. The central nervous system is also present bu t will only be discussed in association with the musculoskeletal system. The same applies to the respiratory system and the cardiovascular system. The cardiovascular or circulatory system consists of the heart and blood vessels which circulate blood to all parts of the body. It interacts with the respiratory system to oxygenate the blood and release carbon dioxide from the body. The circulatory system transports nutrients to the muscles that without them would not be able to function. Through physical conditioning, athletes have enhanced cardiovascular systems, capable of keeping up with the strenuous 3

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Exercise Efficiency for Athletic Performance physical demands found in sports. They often have very efficient blood products along with a well developed heart. Cardiovascular fitness is necessary for success at the elite level in sports. The musculoskeletal system consists of muscles, bones, ligaments, tendons and other collagenous structures with the basic unit of muscle being the sarcomere and its protein myofilaments Different kinematic values can be used to describe the actions of these contractile filaments such as force and velocity, which are both quantitative measures of muscle fiber activation. Contractions at this level are what lead to the macroscopic contractions seen in muscle. Sarcomeres consist of two main proteins, actin and myosin, which overlap each other in parallel. Myosin heads drag their respective myofibril along the length of the actin filaments in a process termed muscle shortening or contraction. There are many sarcomeres, in parallel and in series with each other, which are innervated by motor neurons from the central nervous system. Each motor neuron and its corresponding muscle fibers together are called a motor unit with each muscle being made up of many motor units. When the CNS signals for the muscle to contract, an impulse, traveling from the neuron, causes the subsequent shortening of sarcomeres in the muscle fiber. However, each sarcomere can only shorten a specified distance and takes up a certain volume in the muscle. The force production of the muscle is determined by several factors. They include type of muscle fiber and quantity of them, activation frequency of motor units, size of the muscle and length of the sarcomere. For the purpose ofthis review, only the factors which athletes can enhance will be discussed. 4

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Exercise Efficiency for Athletic Performance There are two main types of skeletal mu cle fiber. low twich fibers ( ype I) or slow oxidative fibers are not easily fatigued and contract slowly. These muscle fiber are found in abundance in long distance runners and others who require maximum muscle economy o er power and speed They are able to produce more ATP than fast twitch fibers and contain more myoglobin as well. ast twitch fibers come in two arieties. Type lib fibers are the fastest contracting skeletal muscle fibers but also the quickest to fatigue. They have few mitochondria and a large store of glycogen and creatine phosphate available for glycolysi The intermediate muscle fiber type is Type II a (Karp, 201 0). The amount of each type of fiber is determined initially by genetics (Simoneau & Bouchard, 1995) but is then influenced by the demands placed on the body. This means an athlete can alter the number of specific fiber types through training. An athlete that needs a large amount of force production very quickly would be better served by fast glycolitic Type II fibers while the opposite goes for marathon runners and long distance swimmers (Costill et al, 1976). Athletes wishing to increase the number of fast glycolytic fiber they have hould train in a manner which uses that fiber type the most, such as in sprints while an endurance runner should train so that they maximize the use of slow oxidative fibers. Howe er, for those athletes who require a more balanced fiber ratio, such as soccer and lacrosse players, training regimens should incorporate both fiber types. Muscle Contraction Skeletal muscle contractions occur when myofilaments in the sarcomere slide by each other shortening the muscle fiber at a certain velocity and with a distinct amount of force. 5

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Exercise Efficiency for Athletic Performance Concentric contractions occur when the muscle fibers shorten while they produce force, resulting in a shortening of the whole muscle as well. Concentric contractions are dominant in the lifting phase of an exercise and serve to change the angle of the joint they control. They are the most widely recognized in contraction type in weight training because they are often associated with doing the most work when lifting weights. However, many workout enthusiasts don't realize that the muscles are still contracting when bringing the weight back down to the starting position. This action is called eccentric contraction and is far more prevalent in lifting than one might realize. Eccentric contractions produce force in a muscle that is actively lengthening. In fact, a muscle undergoing this eccentric contraction can produce more force than one undergoing shortening and use less metabolic fuel (Katz, LaStayo et al, 1999). This type of contraction is dominant in the lowering phase of a lift and usually acts against the force of gravity. Eccentric contractions rely on negative work. They convert mechankal energy into heat and potential energy by storing the elastic energy in flexible elements found in the body. Elastic structures in the muscles such as tendons, ligaments, and microscopic titin filaments contribute to the increase in force found in eccentric contractions (Brunello et al., 2007) by increasing the passive tension of the lengthening muscle. Eccentric or negative training is done by applying force to a lengthening muscle. This is embodied in the down phase in a pull up or push up and the landing phase in a jump. All of these situations involve lengthening of the active muscle. They include the biceps and back muscles in a pull up, the pectoral and triceps muscles in a push up, and the quadriceps muscles in landing. 6

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Exercise Efficiency for Athletic Performance Eccentric loading Rapid Stretch FORCE High Zero Concentric loadilg RATE OF CHANGE IN MUSCLE LENGTH Rapid Shorten Figure 1: Length-force relationship in skeletal muscle (Bloomfield et al., 1994) As the force-velocity curve shows (Figure 1), eccentric contractions produce more force than concentric ones. This means more force is needed against lengthening muscles to improve strength than for a concentric exercise. Remembering that eccentric contractions generate more force than concentric contractions when performing negative exercise is important for maximizing a negative work exercise regimen. The trainee will need more weight and greater resistance than when performing normal concentric exercise. There are many other athletic qualities besides agility speed, strength, power, and endurance that enhance athletic performance. Flexibility, resilience, and mental aptitude all contribute to performance in sport but will not be discussed in this paper. However, a review of these attributes would be beneficial to the sports and fitness communities. Agility is the ability to change direction quickly and smoothly. It is highly prevalent in field sports where motions are not confined to linear planes. Speed is the amount of distance 7

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Exercise Efficiency for Athletic Performance covered in a period of time. It is often synonymous with velocity but velocity implies a direction and speed does not. Strength is the ability to impart force on an object and is quite variable in presentation in sports. Some sports require immense upper body strength while others require only a modicum. Power, on the other hand, is ubiquitous in athletics. It is the amount of work produced in a period of time and is often referred to as an embodiment of strength and speed. This review serves to provide scientific evidence on the effectiveness of many exercise programs circulating through the fitness community. It is intended for use by athletes but can be beneficial for non-athletes as well trying to improve their athletic performance. In fact, many of the advanced techniques proposed require a foundational level of fitness which scores of fitness enthusiasts already possess. For that reason, the tips in this paper can be beneficial to the local gym attendee and elite athlete alike. This review is intended for anyone wishing to maximize their training efficiency, whether it is to reduce time in the gym or simply enhance the effectiveness of a routine. By effectively training in agility, speed, strength, power and endurance an athlete can significantly improve their level of athleticism or athletic fitness. Because increases in fitness have been shown to translate directly into augmented performance in sports, it is highly pursued by established and aspiring athletes alike. The science explained in this review is meant to show the foundation of empirical evidence that supports the methods laid out. Each technique presented has been scientifically tested either in the field or in the laboratory and is recommended by fitness coaches and trained professionals worldwide. By incorporating some of these methods into their regular training routine, athletes can expect to see increased gains in the five athletic characteristics as well as a reduction in time spent in training. 8

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Exercise Efficiency for Athletic Performance Agility Agility is a term used to define the ability of a person to change their course of direction with speed (V escovi, 201 0). The quicker and more graceful a person can make a turn, the greater their agility. This characteristic of athleticism is essential to all athletes who move in more than one direction including, but not limited to, those who play soccer, hockey, rugby, and football. In fact, most professional athletes require well honed agility. Exclusions to this need for agility would be in less mobile athletes such as golfers and bobsled teams. Agility is a complex motor skill requiring braking balance, spatial awareness, and acceleration (V escovi 201 0). It also calls for a great deal of neuromuscular control and a high degree of motor function Many sports injuries occur when a player is changing direction; therefore, the ability for players to turn in a smooth, quick, and controlled manner is essential for maintaining a player's physical integrity as well. Agility is best improved by repetition ofmovements that require the use of its components. Prominent components in agility include braking, balance, spatial awareness or coordination, and acceleration. Enhancement in any one of these areas can lead to an increase in agility. Advantageous to trainees is the fact that most of these characteristics can be trained in concert with other quaJities of athleticism. Realization of agility also includes the implementation of speed strength, and power. However, the following recommendations are made with the goal of specifically improving the skills of braking balance, spatial awareness, and acceleration. Braking is a rather basic move, but when done incorrectly it has the potential to lead to injury. The best way to shorten braking time is to practice running with speed then coming to a 9

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Exercise Efficiency for Athletic Performance complete stop. The concept is easy enough but it is important to do it safely to avoid injury. First of all, it is safer to take multiple short steps when stopping as opposed to fewer large steps (V escovi, 201 0) This process reduces the stress placed on the knee joints as well as reduces the risk of injury to the ligaments in the knee. It is important to understand that agility training is very stressful on the joints and nervous system Repetitions should be limited with quality taking precedence over quantity. During braking, the muscles of the legs act together to reduce the amount of kinetic energy in the body, or perform negative work. This could be demonstrated by slowing from a run, landing from a jump, or coming to a complete stop after moving any part of the body. All of these movements of the body: running, jumping, and other actions, impart momentum to the human body. Momentum is the product of a body's mass and its velocity. An object, such as an athlete, has a given mass and its momentum is, therefore, determined by its velocity The faster an athlete can move the greater their momentum and the greater braking force required to reduce the kinetic energy. Braking force in running comes from the eccentric contractions of the muscles in the legs. It is this braking force that an athlete must be able to generate if he wishes to change direction sharper and quicker than his opponent. Negative Training Braking requires large amounts of eccentric contractions to decelerate the body. Therefore, it is very beneficial to an athlete to train for these lengthening forces. Negative training utilizes weight lifting to activate the muscles while they lengthen This process is performed by contracting the muscle while a weight applies enough force to elongate the muscle 10

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Exercise Efficiency for Athletic Performance Negative training can be done on any muscle group in the body and is therefore, a very versatile training technique that can be incorporated into any workout. By training with a partner or implementing cheating techniques it is possible to use weights that are heavier than what can normally be done alone. The National Strength and Conditioning Association recommends using 125% of a trainee's one-rep max for negative training (Vescovi). This means if the athlete's one rep max on the bench is 200lbs then they should do negative bench presses with 250lbs. When available, the training partner should help raise the weight to its highest point in the lift. The trainee then lowers the weight back to the starting position as slowly as possible. By lifting the weight for the trainee, the partner is bypassing the concentric phase of the lift allowing negative work to be performed. Being that the weight is more than what could normally be lifted concentrically the weight will fall. The force produced by the weight is greater than the force produced by the muscles to keep it up. This downward force causes the motor units involved to contract maximally yet still lengthen. One of the benefits of eccentric training is that it exhausts the muscles much quicker than concentric contractions alone. When a muscle has reached its point of fatigue from concentric exercise, it has still not exhausted its entire energy source. There is still the ability for eccentric contraction (Durell 2009). This property allows quicker muscle growth and greater strength capabilities. Eccentric training is very effective. Even if the maneuvers are executed slower than in concentric exercise they are better at promoting growth. Eccentric training is a must for any athlete who wishes to maximize their workout routine. Negative training can be performed a variety of ways. The most straightforward manner is to focus more on the eccentric portion of any lift. Prolonging the time spent in the eccentric 11

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Exercise Efficiency for Athletic Performance phase will allow the muscles to feel all of the weight for the entire lift. In concentric repetitions weight trainers might ignore the negative phase all together by letting the weight of a barbell lower the load quickly before engaging the muscles at the last moment. Another way to perform eccentric contractions during training is to perform a concentric exercise with both limbs then switch to one limb for the negative portion. This method can be performed without a training partner. In addition, a person can cheat during the concentric phase of a lift by using momentum to get the weight up before focusing on the eccentric portion For example, during a dumbbell curl the trainee can swing the weight upwards using their entire body then catch it at the top in proper curling form and lower the weight slowly. However, cheating can be hazardous as it implements improper form which could lead to injuries such as a slipped disk. Even though some exercises can be performed alone, it is best to have a training partner during negative exercise to avoid the dangers of working with weights an individual cannot normally lift with proper form. Negative training can also be performed to benefit movement in the vertical direction. The strength of elastic structures in the legs is crucial for jumping ability, a necessary attribute for basketball and volleyball players. Upon landing, muscles in the legs contract eccentrically, storing energy into the elastic elements of the leg (Moran & Wallace, 2007). The stronger a person's muscles are during this negative phase the quicker they can recover from the jump and the less chance of injury to the musculature. Plyometrics is proven to improve jumping ability, especially in men (de Villarreal et al, 2009). Similar to most training moves, there is a concentric and eccentric phase to plyometrics. Therefore, performing plyometrics trains the leg muscles both positively and negatively. It is during the loading phase and landing phase that eccentric contractions occur. Without these contractions a person would simply collapse to the ground 12

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Exercise Efficiency for Athletic Performance upon landing from a jump. Eccentric contractions in the leg and hip extensor muscles slow the body's downward acceleration by producing force even while lengthening. Eccentric training is very potent. There is a substantial amount of tension on the muscle during lengthening and the negative phase of weight training exercises. Such strain on the muscle fibers will inevitably lead to damage in the form of tears. On a small scale, these tears are the basis for muscle hypertrophy and strength gains. The muscle fibers with micro tears will heal themselves and come back stronger and larger, therefore, increasing the strength of the muscle (Charge & Rudnicki, 2004). However, due to the efficiency of such a regimen, it is recommended that precautions be taken to avoid overtraining. Negative training should not be performed on consecutive days. The extra damage sustained by the muscle fibers during eccentric exercise requires more time to heal (Armstrong, Ogilvie, & Schwane, 1983). There is also significant neuromuscular impairment (Saxton et al., 1995) which can lead to diminished gains in strength. Eccentric training is paramount for athletes wishing to improve their braking and agility. For example, field players must be able to stop quickly from a sprint so their legs must be trained eccentrically to slow at a maximum rate. Athletes in need of stopping the extension of their arm, such as in the case of a jiu-jitsu fighter being put in an arm bar or a baseball player checking their swing, must train eccentrically to gain the most out of their bicep. There is untapped strength in muscles not trained under negative conditions. Braking ability in some athletes is paramount to achieving success. Eccentric or negative training is invaluable to any workout and should be included in a manner that will maximize results and limit injury. 13

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Exercise Efficiency for Athletic Performance Balance Balan .ce is the ability of the body to keep its center of mass within its base of support. Balance is a crucial yet sometimes overlooked skill in sports. Practically every known sport in the world requires physical balance, even less mobile sports such as golf and equestrianism. Balance refers to the ability to maintain control over ones position either during movement or stationary. Having an advanced sense of control of the body in sports gives an athlete a great advantage over his opponent. Some sports require participants to manipulate their challenger's body position while sustaining their own physical autonomy. An example of this would be in wrestling and martial arts such as judo and jiu-jitsu. Participants must keep their opponent from gaining control of their bodies. This is often difficult when the defensive party has a strong sense of balance and knows how to remain on their feet. Balance is controlled by the cerebellum of the brain (Morton & Bastian, 2004) which receives sensory input from the semicircular canals in the inner ear. Fluids in these canals shift as the position of the head changes causing bending and activation of stereocilia in the lining of the canals. Action potentials then travel through the vestibuloc.ochlear nerve to the cerebellum which then coordinates the information into proprioception, resulting in balance. The brain is capable of synaptic plasticity in the cerebellum (Kano & Kato, 1987). This means balance training could strengthen the connections of nerves involved in stability leading to a greater sense of balance and coordination. A neuromuscular training regimen should be implemented in athletics not only for increased performance but for injury prevention as well. Plyometrics and balance training, which are highly effective in training the neuromuscular system, have been shown to improve balance in female athletes and prevent injury to their highly susceptible anterior cruciate ligament (Myer & Wall, 2006). 14

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Exercise Efficiency for Athletic Performance Balance Training According to a report written by Lindsey J. DiStephano (2009), balance training can greatly improve a person's sense of dynamic and static balance. Some of the training tools shown to produce successful results are tilt boards, wobble boards, balance trampolines, single-leg maneuvers, and others (DiStefano et al 2009) DiStephano also concluded that for best results, a balance training regimen should be implemented at least 3 times a week for 4 weeks and, should include both static balance exercises as well as dynamic. Stability trairung can also be performed in conjunction with a strength trairung regimen as in single-limb training and functional sport training. Many activities in sport require force output in combination with coordination and balance so it makes sense to prepare in a similar manner to real life situations. However, it has been shown that force production decreases under unstable conditions (Kohler et al, 20 I 0). Athletes who wish to augment their neuromuscular ability should include unstable exercises into their regimen but not at the expense of training on stable surfaces (Anderson & Behm, 2005; Kibele & Behm, 2009). Some studies have shown no increase in athleticism after a balance training regimen especially in already athletic individuals (Kibele & Behm, 2009; Cressey et al, 2007). An athlete's trairung time is limited and therefore, very precious. Workout regimens should be tailored to maximize performance and efficiency. Balance training is without a doubt beneficial to the untrained individual. It has been shown to increase sense of balance in the elderly (Madureira et al, 2007) as well as prevent injuries to the lower extremities in athletes (HUbscher et al, 2010; Myer et al, 2006 ; Palmer, 2007). However, due to the lack of evidence 15

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Exercise Efficiency for Athletic Performance that it aids performance in elite athletes, balance training should only be implemented as an injury prevention regimen and not interfere with normal static training. In fact, by participating in sport-related training, the athlete's may be conditioning their sense o f balance as effectively as a balance training regimen. onetheless the li tera tur e has mixed reviews of balance training. Some studies support the regimen as beneficial in increasing balance while others do not. Several papers only tested the elderly and some only tested one training surface. Due to the i ncon sis tencies in the literature, i t is recommended that athletes wishing to improve their balance try multiple training methods and fmd out which ones work for them. However, time spent in normal static training should never be sacrificed for a balance regimen but instead the balance training can be included at the end of a training session. The injury prevention capability of balance training, however, is enough to en ure i ts place in athletic conditioning. Spatial and Situational Awareness Spatial awareness is the ability to be aware of one's position in the environment. This is a crucial skill in sports. Knowing the body's position relative to an opponent, teammates or playing fie ld is tantamount to having the physical ability to play a sport and mandatory for the elite athlete. Proprioception is the awareness of a person's own body pos ition, while spatial awareness is broader i n that i t incorporates knowledge of everything outside the body including people, objects and other stimuli. Having a sense of the surrounding world demands integration o f many if not all the senses. In sports, the most used senses are touch, sight, and hearing. By combining all these senses, an athlete can gain an understanding of the playing field, adjust their own position accordingly, and do so all while in the motion of play. 16

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Exercise Efficiency for Athletic Performance Spatial awareness is very similar to situational awareness and the two are interchangeable in this review. The difference between situational and spatial awareness is that situational awareness incorporates not only the environment into brain computations but also the actions of oneself and others and how they will affect the near future. An example of this would be that spatial awareness of a racquetball court and an opponent might elicit the location of the opponent, their speed of motion, and the hand with which they hold the racquet. A sense of situational awareness might include the aforementioned knowledge as well as the opponent's level of fitness, the time it takes them to cross the court, and their skill level in picking up low shots and then deciding where to hit the ball next. Knowledge of the situation will lead to informed decision making and with practice could lead to success in anticipation of an opponent s or teammate s moves. Cultivating these skills is a must for those wishing to improve their athletic performance. The question is how one does so through a workout regimen. Spatial awareness training can be conducted in two manners. Training can occur in real sport simulation such as in practice or in individualized, focused awareness training drills. Furthermore, practice can be conducted in the laboratory setting as well as the field (Armstrong et al, 1983). Athletes who study film of their sport have greater ability to anticipate an opponent's action in a real life competition. However, it takes about ten years of purposeful practice to achieve expert status in sport-specific spatial awareness (Williams et al, 2003). Deliberate practice is a proven method of attaining elite performance in sports but the type of goals in which athletes set for them plays a role in the efficacy of that practice. Athletes desiring an effective practice must maintain the goal of improving their ability in the sport (Ericsson et al, 1993; Ericsson & Chamess, 1994; Starkes & Ericsson, 2003). Passion is also a requirement for elite status but the passion must be hannonious and not obsessive (Valleranda et al 2007,2008). 17

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Exercise Efficiency for Athletic Performance By practicing effectively, athletes can increase their spatial ability. This requires a variety of training situations such as individual practice training with teammates and competing against others. There is a positive correlation between deliberate practice time and performance so for those who wish to improve their spatial awareness, but no longer train in a sport; they should participate, as much as possible, in friendly competition. Accele ration The physics definition of acceleration is the change in velocity over time. In sports, it is when an object or athlete moves faster or quickens. Anything that goes from no movement to movement is undergoing acceleration. A ball held by a lacrosse stick can be passed to another player by accelerating it through the air under ballistic motion. However, in terms of agility, acceleration is the final step in changing directions with speed. The steps in agility are deceleration or braking turning, then acceleration in the new direction It is this final burst that can really give an athlete an advantage over their opponent. A wide receiver can elude his cover and is open for a pass, a soccer player can get by a defender and attack the goal, or a tennis player can cut back across the court to reach a ball. All are examples of agility in action. Acceleration in sports usually only lasts a short time and requires a short burst in speed. The difference between acceleration in agility and in a straight sprint is that the acceleration comes after a turn in which the body's momentum may still be heading in the previous direction. An athlete must overcome his momentum and is therefore, facing more force against himself than just his inertia. This extra force should be taken into account when training. 18

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Exercise Efficiency for Athletic Performance Proper acceleration technique should be implemented in acceleration training. However, it is important to understand basic biomechanics before training. The goal of sprinting is to increase the force in the horizontal direction. Any force in the vertical vector is lost. This leads to the importance of the angle in the ankle of the first step. The proper angle of the shin of the leading leg is 45 (Parisi, 2008). Any straighter and there is a loss of force in the vertical plane (White, 2006). This angle should be maintained for the first few steps of acceleration. This acute angle will cause the body to lean forward at the hips making the runner feel like they are falling. It is this feeling that causes them to put out the next leg to step on. If this step is too vertical then the runner will decelerate as the legs are then acting as brakes. If the proper angle is kept and the body's center of gravity is in front of the lead leg then the acceleration process will continue. The same idea is used in changing directions. If the player is moving laterally then the knees must be farther in the direction of travel than the toes. This means the outside foot must be extended more lateral to the midline than the corresponding knee and the inside foot more medial. This will place the acceleration vector in the direction of the shuffle. Acceleration training is very taxing on the central nervous system as one of its purposes is to strengthen neurological firing patterns for recruited muscle fibers. If this neuromuscular system becomes fatigued, then the efficiency of the training diminishes (Seith, 201 0) Acceleration training is very technical and should only be performed under full rest. All types of lower extremity injuries can occur when the participant is fatigued (Palmer, 2007; Gutierrez et al, 2007; Greig 2009) and the rate of fatigability of muscles increases when they are not fully recovered As an athlete sprints, their muscle fibers fatigue and produce less force for propulsion (Enoka et al, 2004) This force is necessary in acceleration training and without it the training is rather useless. Rest should be incorporated in every training session. Athletes should be given 1 19

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Exercise Efficiency for Athletic Performance minute of rest for every 10 meters sprinted (Beith, 2010). There should also be 36-48 hours of rest in between training sessions to allow the muscle fibers and central nervous system time to recover completely. Acceleration training can be performed with resistance placed on the running athlete. Trainees can pull a weighted sled tow a teammate, or run uphill. Evidence shows that resisted sprint training can lead to improvements in the acceleration phase of a sprint but not the remainder of the run at maximum speed (Cronin et al, 2006; Spinks et al 2007 ; Zafeiridis et al, 2005). For most field sports, however, most athletes do not reach maximum velocity very often. Short sprints of mostly the acceleration phase are more common (Cronin et al, 2006) During resisted running and uphill running the body s position reflects that of the acceleration phase of running. This could be the explanation for the improvement in the acceleration phase only of a sprint. Athletes training to improve their acceleration should incorporate resisted sprint training in their running regimen. Agility is a demonstrably important quality in elite athletes. It requires excellent capability in the areas of braking, balance, spatial awareness, and acceleration. Athletes wishing to improve their agility should strive to train in the aforementioned traits. However due to the limited time and energy an athlete can give to training, athletes should focus on the most efficient and effective training methods. By concentrating on the core characteristics of agility a trainee can ensure an improvement in the performance of their sport, especially in areas requiring a quick, agile competitor Agility training also has the added benefit of reducing lower extremity injuries By strengthening the neuromuscular connection, athletes will have a higher sense of motor control and be able to reduce the chances of season or career ending injury. Training 20

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Exercise Efficiency for Athletic Performance proper fonn during agility workouts is a necessary precaution and will lead to overall benefits in perfonnance and health. Speed The acceleration component of agility is also a large element in the athletic trait of speed. Speed can take many forms such as running speed, arm swing speed, and swimming speed. However, the basic definition of speed is the amount of distance covered in a period of time. This can mean from the start of motion to the end or any period in between that. Acceleration was already covered in the section on agility so this portion will focus on the length of time where the body part in motion is at maximum velocity or maximum sustainable velocity. In a I OOm dash, this portion is described as the period between about 36m-lOOm (Delecuse et al, 1995). This velocity can also be described as the velocity of maximal oxygen uptake (Bundle et al, 2003). Running speed is determined by stride length and stride frequency. The optimal running speed for an athlete will incorporate the optimal stride frequency and optimal length. This does not mean the most economic running speed for athletes. That will be discussed in the section on endurance. This portion of the review attempts to elucidate the biomechanics of running speed and apply it to the optimum method to train for speed. There are several trainable factors that influence the speed of a runner. Whether running in a marathon or a 400 meter race, there are proven ways to improve an athlete's speed. Some methods include maintaining proper running mechanics while others try to develop muscular capacity. When trying to develop the proper mechanics of running it is important to understand the gait cycle or repetitive pattern of the legs during locomotion. This gait cycle is different for 21

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Exercise Efficiency for Athletic Performance each person due to differing leg lengths and levels of flexibility, however, there are signiture patterns that apply to everyone. The gait cycle starts at initial contact where the heel or toes first touch the ground. Then as the body moves forward, the center of gravity moves over the point of ground contact and beyond the front of the foot. The foot then extends rearward until the last point of contact. This is the end of the stance phase and the beginning of the swing phase The foot is then raised by the runner and swung in front of the center of mass until it hits the ground and the cycle starts again (Novacheck, 1998). By analyzing the gait cycle athletes and their coaches can determine which forces are present at what point in the cycle and how to use them to the advantage of the runner. Horizontal forces are the most important forces in running as they provide the forward propulsion needed by the runner. On the other hand, in the braking phase, horizontal forces acting against the runner exist as well. This occurs when the foot hits the ground at the end of the swing phase. Rearward facing ground reaction forces are strongest at this point. The force vector for a foot that lands heel first extends behind the ankle and in front of the knee and hip. The torque produced at the ankle causes it to extend or undergo plantarflexion. At the knee the torque causes extension while at the hip there is massive force causing flexion (Ayyappa, 1997). Muscles at these joints may need to resist these forces to continue forward propulsion. The muscles of the lower leg, such as the pretibials, must undergo strong eccentric contractions to prevent plantarflexion of the ankle and allow a rocking motion to occur about the heel and therefore, encourage forward momentum to continue. Athletes would benefit from training their lower musculature with eccentric exercise. This would stiffen the calf muscles and allow less plantarflexion of the ankle at a reduced metabolic cost (Lindstedt et al, 200 I). Along with vaulting the body over the heel, the stiff ankle joint will cause the knee to flex and finish the 22

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Exercise Efficiency for Athletic Performance stance phase. The vertical force on the knee is dampened by the eccentric contractions of the quadriceps which work to move the femur over the lower leg and also continue the forward momentum of the body. Eccentric training of the quadriceps would greatly benefit an athletes ability to run faster by stiffening the muscles and reducing the time of contact with the ground. The hip extensors bear the brunt of the force slammed on the body by the ground (Cavanagh, 1980). Astonishingly, this force can be 2.5-3.0 times greater than the person's body weight (Bassey, 1995). During the beginning of the stance phase when the heel strikes the ground the ground reaction force works to flex the hip The hip extensors, including the hamstrings and gluteaus maximus work together to limit the flexion of the hip during the loading phase of the stance. As the gait cycle progresses and the center of mass moves beyond the lower leg, the stress on the hip extensors moves from the hamstrings to the glutes (Lindstedt et al, 2001). Once again, eccentric contractions dominate during the loading phase and negative training would surely improve the athlete's ability to extend the leg at the end of the stance phase. Great amounts of force are needed to overcome the rearward ground reaction force at the beginning of the stance phase as well as to propel the body forward over the shin and ankle. By training these muscles extensively, an athlete will be able to increase the propulsive forces they can produce as well as maximize the stiffuess of their muscles for a more efficient load rebound. This increase in horizontal force will minimize vertical forces and lead to an enhanced stride frequency. To increase speed a runner must increase stride frequency, stride length or both. Many might think that if they just increase their endurance they will be able to run faster. This is plausible but very difficult without proper training of the neuromuscular system. While running, the central nervous system employs groups of neurons called central pattern generators. Once 23

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Exercise Efficiency for Athletic Performance these neurons become activated, they oscillate in a rhythmic pattern without any further control from the higher brain structures (Marder & Bucher 2001). CPG's can be found in running, swimming, and breathing and usually have one or a few desired frequencies. However, by repeated altering of afferent input by sensory neurons, the CPG's pattern can be tuned to a new freq uency (Pearson, 2000). This means that little improvements in posture, stride frequency and gait mechanics can be trained into the central nervous system with repeated bouts of exercise. In fact, researchers have identified one type of cell, called a Vl spinal neuron, that may play an important role in speeding up the CPG's frequency (Gosgnach et al, 2006). HarrisWarrick and Cohen ( 1985) discovered that the neurotransmitter serotonin can act upon the CPG' s of locomot ion a beneficial piece of infonnation for athletes because serotonin levels increase with vigorous exercise (Chaouloff, 1997). All ofthis evidence shows that CPG's can be altered through training therefore making speed training effective in increasing the level of speed capable by athletes. Speed training aims to increase the speed of central pattern generators found in the central nervous system as well as increase endurance. Athletes wishing to increase their speed should perfonn speed exercises at least 3 training sessions per week for 6-12 weeks. It is important to increase the intensity of these sessions every two weeks to avoid overtaining yet still overcome muscular adaptation. These are just gui delines however. The main idea to keep in mind when trying to increase running speed is to just train faster. By running faster in training than they would during competition, an athlete will train their muscles and central nervous system to work at that speed. Of course there will be aerobic limitations inherent in this type of training but they can be overcome simply by implementing periods of rest. 24

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Exercise Efficiency for Athletic Performance The most effective method of speed training is speed intervals. Speed intervals consist of measured distances which are run at a faster than competition pace followed by a recovery period (Holcomb, 20 l 0). The optimal recovery period is determined by the indiv idual or coach and is dependent on the speed and distance of the interval. Longer runs at slower paces require shorter rest periods while faster paces require longer recovery periods. For long distance runs, the recovery period should consist of walking or a light jog. For shorter distances walking or stationary resting is acceptable. An example of a speed interval training routine for a mid distance runner is listed below. Table l Week# Distance Rest Distance Repeats Total Distance Ran 1 400m lOOm 10 4000m 2 400m lOOm lO 4000m 3 800m lOOm 5 4000m 4 800m lOOm 5 4000m 5 I 200m lOOm 2 2400m 6 1200m lOOm 2 2400m Table 1 : Example s i x week speed i nterval program Overall, there are several methods of training possible to improve a runner's speed. Athletes should try these techniques and find out which ones work best for them. It is important to include a variety of routines, however in order to prevent the plateau effect and train different 25

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Exercise Efficiency for Athletic Performance aspects of the running musculature. Implementing a program of increasing inten ity i necessary to prevent plateaus as well. As mentioned above, the central nervous system has very moldable central pattern generators which dictate the continuous speed an athlete runs at. Athletes should attempt to influence these neural networks for ga ins in speed and efficiency. Endurance will come with running but improvements in speed will only come from training. Strength Physical strength is the ability to apply a force on an object in order to m ove it or maintain its position Strength is an interesting measure of human health because it naturally increases with age and physical development. In fac t it takes a substantial amount of malnutrition and sedentary living to prevent gains in strength in younger individuals Of course this does not mean a person's strength will increase infinitely by doing nothing. In one study of 114 males from 11 year to 70 years old, strength was shown to increase up to about the 30's in men. From then on strength plateaued until the SO' s then decreased as the men grew in age (Larsson & Grim by, 1979). Mammals have the ability to increase their strength because of some of the inherent qualities found in muscle. It used to be thought that muscle fibers only underwent hypertrophy and that the number of fibers at birth remains the same throughout life (Antonio & Gonyea, 1993). Recently, however the process of fiber hyperplasia has been investigated (Gonyea et al, 2004). It has been proposed that the hyperplasia comes from differentiation of satellite cells (Kadi et al, 1999) splitting of existing muscle fibers (Gonyea et al, 2008), or de novo production of new fibers (Antonio & Gonyea, 1993; Giddings & Gonyea, 2005) The important piece of informa tion for 26

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Exercise Efficiency for Athletic Performance athletes is how these researchers promoted muscle hyperplasia. It was rather simple. They simply overloaded the muscle with resistance. This is basic weight training. It turns out that anyone can increase their muscle fiber number simply by lifting weights. The studies did all last for more than 34 weeks though so huge increases in fiber hyperplasia should not be expected right away. One other studied method was stretch overload (Gollnick et al, 1983; Kelly, 1996). Stretch overload was performed by attaching a weight to the wing of a bird. Hyperplasia occurred in the pectoralis muscle only after significant hypertrophy occurred first (Antonio & Gonyea, 1993) but hyperplasia did still occur 28 days later. Muscle contractile force can be augmented by increasing the cross-sectional area of the muscle. Both fiber hypertrophy and hyperplasia can accomplish this. Most athletes know about muscle hypertrophy. It is simple and well documented, lift weights regularly and your muscles will get bigger and stronger. Hyperplasia, however, is a relatively knewly discovered phenomenon. It occurs with regular weight lifting but at a slower pace than hypertrophy (Antonio & Gonyea, 1993). This is due to the mechanism by which it might work. It is proposed that weighted stretching expands the fascia and connective tissues of muscles allowing them to grow. One example of a stretch overloading exercise would be overhead tricep extensions with full range of motion. The extra space is then filled by growing myocytes and new muscle fibers either from differentiated satellite cells, split muscle fibers, or brand new fibers. More research must be conducted in humans to determine the cause of hyperplasia One thing is rather certain. Hyperplasia does not occur in low intensity, high repetition lifting. Routines must be high in intensity for hyperplasia to occur (Giddings & Gonyea, 2005). 27

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Exercise Efficiency for Athletic Performance Strength Training There is a direct correlation between the size of muscles and the amount of force they can generate. What is the best way to increase strength? There are thousands of weight lifting exercises floating around the internet for every muscle group in the human body. Knowing which ones are most effective and safest will give athletes an advantage in the weight room. By implementing these moves, trainees can get the most out of their strength training routine in the shortest amount of time, giving them more time to work on skills directly related to their sport. There are some basic principles that should be found in every strength training regimen. The ftrst step is to have a plan. Planning ahead will help to make sure there are set goals for the workout before the middle of a program when fatigue starts to take its toll. This will lead to higher goals to reach for and reduce the chance selling oneself short. Planning can also lead to less time in the gym and more motivation to complete everything needed The second step in a good weight lifting program is to warm up. An efficient method is dynamic stretching. Dynamic stretches involve moving the body in its full range of motion, gradually increasing reach or speed (Kurz, 2003). Stretching should not be performed on cold muscles. It is important to warm up first. This can be done by joint rotations and then aerobic activity (Appleton). It is important to not perform static stretches before working out as it can diminish athletic capability and power output (Bradley et al, 2007; Fletcher & Jones 2004) After a proper warm up in which the muscles and nervous system are now primed for work, an athlete can begin their weight lifting routine. Each routine should have a specific set of muscles being trained that session. Muscles should not be trained everyday inorder to avoid overtraining and injury so athletes should determine beforehand which muscles they will train. 28

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Exercise Efficiency for Athletic Performance It has been shown that only 1 day a week of training is necessary to maintain muscle ability (DeRenne et al, 1996; Graves et al., 1990). However, any good athlete should be motivated to improve their strength and not just maintain it. This is why 1-2 workouts per muscle group is recommended. A pioneer in the field of weight lifting was Arthur Jones (Jones, 1970, 1971, 1982, 1993a, 1993b, 2003). He recommended that people perform one set per exercise to volitional failure no more than twice a week. Each set should consist of 8-12 well-controlled repetitions This amounts to about 90 minutes of training per week and would be the optimal training regimen for athletes pressed for time. However, the ational Strength and Conditioning Association recommends multiple sets for the greatest results in athletes and experienced lifters (National Strength and Conditioning Association, 2003). There is a myriad of conflicting literature on the subject of set numbers and exercise frequency. For the reason that there is evidence supporting both low quantities and high quantities, athletes are recommended to perform more in the off season as there is more time available to train. However, low volume training would be most efficient during the competition season. After a grueling workout, popular opinion says to cool down. Cool downs usually entail slowing down an activity in order to control the heart rate and breathing. They also may include a stretching routine under the reasoning that it will reduce delayed onset muscle soreness (DOMS). Although this training staple is widely recommended by physiologists and personal trainers alike, there is no scientific evidence to support it (Herbert & Gabriel, 2002). Stretching post-exercise does not reduce soreness and there is no evidence that slowing the heart and lungs is beneficial (Herbert & Gabriel, 2002). However, there is not enough research in the area to make any certain conclusions. There may very well be a benefit to cooling down the body back 29

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Exercise Efficiency for Athletic Performance to resting levels immediately after exercise. Therefore, it is recommended, at least as a precaution, that athletes spend some time cooling down especially after intense training. One known benefit of the cool down is that it prevents fainting. During exercise, large quantities of blood get shuttled into the legs. Once the workout ends the muscles are no longer squeezing the blood back up to the heart and the blood stays in the legs (Somerville, 2005). This pooling effect can cause a person to faint. A void this by simply walking around for a short while before completely stopping and sitting. Weight Lifting Principles There are a few basic principles to adhere to for a weight lifting program to be successful. The first rule is the concept of overload. For muscles to grow, they must be stimulated more than they are adapted to. An athlete should not perform a lift with a weight they can rep 50 times. This does not provide enough tension for the muscle and therefore, it will not grow. The second concept is development. As muscles are put under repeated bouts of exercise, they become stronger and adapt to the stimulus. This means that a trainee must continually increase the resistance against these muscles to continue the growth process. These two principles of weight lifting are the most important rules to follow in weight training. A true competitor should always strive to become better than their opponent. If they are not taking the necessary steps to improve their strength then they are giving an advantage to the other guy. Strength training is a simple method of improving athleticism that has been practiced since before ancient Greece. Hippocrates put it in very straightforward terms, "that which is used develops, and that which is not used wastes away." Even the densest of neophytes can have 30

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Exercise Efficiency for Athletic Performance success in weight training simply by doing the basic moves. However, by analyzing human physiology and the biomechanics of muscle athletes can employ more advanced techniques to maximize the productivity of their workouts. Advanced Strength Training Techniques Eccentric training is an example of an advanced technique which uses science to get the most out of muscles. Muscles undergoing eccentric contraction produce more force than during concentric contraction. Eccentric training has been shown to induce greater increases in strength and muscle than concentric training alone (Hortobagyi et al, 1996a 1999b; Farthing & Chilibeck, 2003 ; LaStayo et al 2003). It also appears to induce hypertrophy at a quicker rate (Farthing & Chilibeck, 2003) (LaStayo et al, 2003). In view of the fact that eccentric contractions cause more damage to muscle fibers and therefore, induce more delayed onset muscle soreness than concentric contractions, eccentric training should only be performed 1 to 2 times per week with at least 72 hours of rest in between sessions. Another advanced technique with huge benefits for athletes would be functional strength training (FST). FST is a technique which works to enhance the performance of muscles as well as the neuromuscular system. It serves to improve strength in a manner which directly improves the performance of a particular movement (Bryant, 1999). FST is performed not by isolating specific muscle groups but by recruiting a variety of muscle groups which work to execute a movement. An example would be lifting something heavy from the ground to above the head. A traditional method of weight lifting for the task would be to implement exercises which strengthen the thighs, back and shoulders. For a trainee who does split routines, this might take 31

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Exercise Efficiency for Athletic Performance three days a week of training with each day encompassing a different muscle group. An FST trainee on the other hand might train legs and hips one day and vertical pushing movement on another. Functional exercises applicable to the example might be dead lifts, squats clean and jerks, and overhead presses. This is much simpler than having to do calf raises, leg extensions lower back extensions, bent-over rows, military press, front shoulder raises and a myriad of other isolating exercises. The advantage of FST is that the maneuvers train many muscles in unison which reduces the amount of time spent in the weight room and increases the efficiency of the workout. An additional benefit of functional strength training is the neuromuscular demand it places on the body When the body performs for examp l e a preacher curl the brain enhances synaptic connections associated with that exercise. This translates to better neuromuscu l ar control of the biceps when doing preacher curls later on. However how does this benefit a man trying to pick up his daughter to give her a kis ? If the man is focused on lifting the girl with his biceps then he is most likely not aware of his posture or lifting technique because his brain has never been trained to do both bicep activation and squats. Through FST, the father would train his core at the same time as his biceps and improve the neuromuscular control of both. There is a high degree of turnover in functional training from weight room to field. The purpose of FST is to trai n the body to do movements it would do in the real world. It accomplishes this by training the neuromuscular connection (Fimland et al, 2009), not just by increasing the force capacity of a muscle (Cunningham, 2000). One tenet of FST is that the exercise should be done while standing. This will mimic the scenarios common to the sports realm and engage all muscles required for stabilization and balance By training under similar ground reaction forces found on the field or court, an athlete will better prepare their central 32

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Exercise Efficiency for Athlet i c Performance nervous system to engage in proprioceptively demanding activities found in competition (Keogh et al, 1999) The correlation can be seen in the default posture assumed by athletes in many sports. The stance at the beginning of the dead lift is the exact same position held by linebackers in wait attentative hockey goalies, and basketball centers trying to box out an opponent. This shallow squat lowers the body s center of gravity and loads the elastic elements in the legs with some potential energy to be used in the ensuing movement. Another tenet of FST is the use of the body s inherent energy saving methods. By tren g thening this system an athlete can maximize the economy oftheir body. An example of this would be the push press. T his exercise is similar to a mil itary press but it is performed standing up and uses the lower extremities to aid in the lift The trainee uses their legs to impart upward momentum at the beginning of the lift and help lift the weight above the head. The push press activates reflexes found in the calves and thighs that are found in jumping as well as connect it neurally to raising the arms Push presses mimic rebounding in basketball and should be incorporated in the workouts of basketball and volleyball players. The loading mechanism inherent in the push press is a method the body uses to save energy The body weight of the individual imparts force onto the elastic elements ofthe legs and hips converting potential mechanical energy into elastic potential energy which can then be released as kinetic energy during the jump. The benefits of functional strength training for athletes are indisputable It almost seems that FST is the only workout program necessary for them to succeed. Although the benefits of F Tare many, F T should not substitute a regular lifting program but ought to be used as a supplement to an effective resistance regimen. Functional Strength training does not produce muscl e growth at the same rate as traditional methods The force produced by the quadriceps in a 33

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Exercise Efficiency for Athletic Performance push press is nowhere near that of a leg extension. Functional training is a technique that trains the neuromuscular system at the cost of force production in individual muscle fibers However, these benefits are more than worth including the technique into a weekly regimen. There are many more advanced weight training techniques for athletes to experiment with and use to add variety to a workout Some of these techniques include antagonist muscle supersets, breakdowns, pyramid sets, super slow motion reps, partial reps, rest pauses and forced repetitions. Only the first two however, have scientific evidence supporting their usage. In fact, super slow reps and rest pause usage is discouraged for athletes wishing to improve the efficacy of their workouts (DeRenne et al, 1996). Therefore, the techniques most recommended by this review are supersets and breakdowns. Antagonist muscle supersets consist of individual exercises, which train opposing muscles, with no rest in between (Ridgely, 2004). This method utilizes the antagonist nature of conflicting muscle groups. An example of this superset would be perfonning a set of bicep curls then immediately switching to triceps extensions. The biceps and triceps are antagonists of one another. While the biceps are contracting the triceps are lengthening. Other antagonist muscle pairs are chest and back and quadriceps and hamstrings. There is a lack of research that has been done to investigate the strength benefits of supersets with most support coming from weight lifting icons such as Charles Poliquin, Arnold Schwarzenegger and Dave Draper. There has been, however, research looking into the energy expenditure of the maneuver (Kelleher et al, 201 0). Supersets increase post-exercise energy expenditure and oxygen consumption which translates to greater muscle endurance and fat loss (Benton & Swan, 2009). Lean body mass has been shown to be positively correlated with athletic perfonnance (Venkata et al, 2004) so supersets may offer an advantage to those athletes utilizing the technique. Furthennore, supersets can be used by an 34

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Exercise Efficiency for Athletic Performance athlete to increase the intensity of the workout and reduce the amount of time spent in the gym (Allerheiligen, 2003). Another advanced strength training technique that athletes may want to try is breakdowns or stripping. Breakdowns are executed by performing an exercise set to failure then immediately reducing the weight and carrying out another set to failure. The number of sets performed should reflect the goals of the athlete. If the desire is to focus on strength endurance then more sets should be performed Breakdowns have been shown to induce greater strength gains than traditional heavy weight, low repetition training (Keogh et al, 1999; Berger & Hardage, 1967). The most likely reason for this is that breakdowns activate the neuromuscular system more that hea y weight training (Keogh et al, 1999). This translates to more force production by the muscle and greater fiber hypertrophy. The one downside of breakdowns, however is that it does not increase muscular power as effectively as heavy weight training because of the slower velocities occurring during the lift. Power Power is the amount of work done over time and work is the force times the distance traveled so power can be described as the amount of work produced over a certain distance during a specific period of time. In simpler terms, power is force times velocity. For a defensive lineman, power translates into how hard and fast they can push an opponent out of the way or into the quarterback. For a sprinter, it's the amount of force the legs can produce at the quickest rate to get them across the finish line. At the level of the muscle fiber, there is a predictable relationship between contractile force and velocity shown by Figure2. 35

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Exercise Efficiency for Athletic Performance ... ... .... Power output \ \ \ \ \ \ \ \ load Of' Ioree Figure 2: Force veloc i ty relationship in skeletal muscle As demonstrated in Figure 2, there is a maximum velocity and force of contraction for skeletal muscle. When at V max, the force produced by the muscle contraction is at its lowest. This means the muscle is able to contract very quickly but with little to no force. This is not applicable for human locomotion because muscles must produce force to create a torque around joints. On the other end of the spectrum, a muscle at maximum force is useless for motion because there is no muscle velocity. Also shown in Figure 2 is the power curve for skeletal muscle. At peak power, the velocity is about one-third that of V max Power is a very important quality in athletes and often utilized in sporting events, meanwhile, maximum force output is not usually attainable or needed in sports. Instead, the goal is to produce the most force possible in the shortest amount of time (Newton & Kraemer, 1994 ). Nearly every type of athlete relies on short bursts of energy such as in a sprint, jump, or throw. Because power is dependent on time, power is often referred to as explosiveness. 36

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Exercise Effic i ency for Athletic Performance Power Training The main goal in power training is to move the weights in the shortest amount of time. It is one of the more techn i cally challenging programs and therefore, requires a well developed sense of functional strength. Strength is an important aspect of power. By strengthening the muscles, a person can positively influence the force production portion of power (Wilson et al, 1993). The simplest way to do this i s to perform heavy wei ght training Having an establ i shed baseline level of strength prevents injury and makes the explosiveness aspect of the program more effective. Strength is required to overcome the initial inertia of the trainee but there are some limits that need to be set in order to develop power. Because most athletes are already well trained, heavy weight training is not recommended for power enhancement (Baker 2001). It is therefore recommended then that athletes train for strength before they embark on a power regimen. Once the strength base is established, it is important to progress slowly in order to effectively train the neuromuscular system and avoid injury. Power training for ath l etes should be specific to their sport in order to maxim ize the efficiency of the routine. A soccer player does not need powerful pectoral muscles like an offensive lineman and therefore, does not need to perform high power bench presses or plyometrics pushups. If training simply for physical fitness and health, large groups of muscles should be incorporated in actions similar to functional training A power training is fundamentally doing a lift where high power can be generated in the concentric phase any exercise can be perfonned for power It is crucial nonetheless that these exercises be safe and effective. The most efficient exercises include those that require no effort in the eccentric phase to decelerate the weight. ccentric contractions are more physically 37

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Exercise Efficiency for Athletic Performance taxing and power moves should only be done when not fatigued. Two categories of power training that do not require deceleration are ballistics and plyometrics. Ballistics Training Ballistic training incorporates movements which produce high velocity and power through the acceleration phase of the lift then release control of the weight through projection Usually this process mimics throwing motions and jumping motions Examples of ballistic exercises include medicine ball throws, squat jumps and Smith machine bench throws (Clark et al, 2008). One of the main benefits of this training style is the recruitment of Type II muscle fibers (Scheeu, 2004). These fibers re spond best to high intensity training and contract quickly and forcefully. Ballistics t raining also leads to greater firing frequency in motor neurons (Van Cutsem et al, 1998; Desmedt, 1977), producing more force per time period. The trick to ballistic training is to get the weight moving fast enough to impart momentum on the object in order to continue the movement beyond the control of the user This is the epitomy of power training. A large quantity force is produced in such a short time that the muscles are flooded with neural activation and growth hormone. Jumping moves are usually done with added weight. Squat jumps, the most basic of jumping maneuvers, require the trainee to completely lift off the ground The leg muscles must provide enough force to not only lift the weight but propel it into the air. The amount of force produced by the muscles will not be as great as in static lifting but the velocity will be much greater and therefore power will be greater as well. It has actually been shown that static lifting impairs the rate of force production in muscles (Hakk i nen et al, 1989) while explosive exercises increase it (Wilson et al, 1993). 38

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Exercise Efficiency for Athletic Performance Safety must not be overlooked when performing ballistic moves. Smith machines are probably the safest method oftrainjng baJlistically with a barbell. There are inherent dangers in throwing heavy objects In a bench throw, the barbell is launched out of the hands and into an uncontrolled free-fall. The trainee must catch the barbell or risk serious crushing injury. One safety precaution to avoid this is to use guard rails that stop the weight from dropping below a certain point. Smith machines incorporate barbells into fixed vertical paths by guiding them with rails. This keeps the weight in one plane of motion and makes it easier to catch. They also provide safety guards to limit the depth of travel of the bar Some of the most effective and popular ballistic moves do not involve releasing the weight. The olympic lifts power cleans, snatches, and clean and jerks, require the trainee to provide enough upward momentum to the barbell to raise the weight into a state of zero gravity before catching" it around shoulder level or above the head. The lifter never actually takes their hands off the bar but simply uses the short period of weightlessness to switch the arm position from above the bar to under the bar (Oxenham 2006). Furthermore, the barbell should never move in the horizontal direction to avoid injury from unwelcomed forces straying from the vertical vector. Momentum is often taughted as a risk factor for injury during exercise. Lack of control of a load can lead to forces acting injuriously in undersired vectors. The body may not be able to prevent trauma in these directions due to lack of range of motion or strength. One example would be damage to the rotator cuff from bad form in the military press. Lower back injuries are especially common in the olympic lifts. The dangers associated with lifting objects incorrectly are particularly inherent in olympic lifts but can easily be avoided by using proper technique. 39

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Exercise Efficiency for Athletic Performance Athletes who have never performed olympic lifts should first seek guidance on correct technique before embarking on an olympic/ballistic lifting regimen. Ballistic training is a very practical method of improving one's athleticism as it relates to a specific sport. The power generated in explosive movements is the same type of power needed by athletes in the sporting arena. Athletes can benefit from ba l listic training by improvments in the force production of type II fibers augmentation the cardiovascular system and strengthening of the neuromuscular system. Athletes would be wise to follow a common adage thrown around by strength training specialists, 'to be fast, train fast. However ballistic training follows a slight variation, "to be powerful, generate power. Pl y ometric s Plyometrics is a training system where explosive movements are coupled with the stretch reflexes of the body (Quinn, 2008). The principle ofplyometrics is that the muscles be stretched and contract eccentrically before they contract concentrically (McBride et al 2008). This action generates great amounts of power and, ifperfonned correctly and safely can have performance benefits for well trained athletes (Adams et al, 1992; Santos & Janeir a, 200 8; de Villarreal et al, 2009). It is especially beneficial for female athletes wishjng to reduce the chances of injury to the lower extremities (Hewett et al, 1996; Lim et al, 2009) (Myer et al, 2005). Athletes who incorporated plyometrics into their resistance training regimen showed improvements in both power and speed (Myer et al, 2006; Adams et aJ, 1992; Luebbers et al 2003). Plyometric training should be incorporated into an exercise regimen for athletes who require high j umping ability, quick acceleration and powerful leg contractions To avoid injury, 40

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Exercise Efficiency for Athletic Performance athletes should first have a solid foundational strength. Landing from high jumps places large eccentric forces on the muscles of the legs and therefore it is recommended that athletes protect themsel es by performing eccentric training before embarking on a plyometrics program. The eccentric training will stiffen the leg muscles which results in more efficient elastic recoil and consequently more force production. Because of the high forces produced in plyometrics, it is recommended that this type of training be performed under adequet rest and no more than 1-2 times per week (Quinn, 2008) This will ensure a fully functional neuromuscular system and properly repaired muscle fibers. Plyometric training can impart very high forces on tbe joints, especially those of the knees, hips and ankles. Furthermore, the extent of eccentric contractions could lead to delayed onset muscle soreness (DOM ). DOMS can be prevented, however, by performing aquatic plyometrics (Robinson et al, 2004) T he grea test ground reaction forces were measured during the landin g phase of jumps, espe-Cially drop jumps (Potach, 2004). Drop jumps are not recommended over 46cm (Ebben, 2007) and should be within 20cm to 40cm (Komi, 1986) for this reason. To dissipate this force, athletes should land' softly" by landing on the toes and rolling to the heel, thereby, increasing the surface area (Quinn 2008) and dispersing the force. By watching someone perform jump training, the most common form of pi yo metric training, the observer will notice that the jumper first lowers the body before taking off. This process serves to stretch the muscles of the posterior chain and initiate the stretc h shortening cycle (Asmussen & BondePetersen, 2008). This is the difference between ballistic training and plyometrics. Ballistic training starts from a still position before generating power while plyometrics relies on the elastic elements in muscle to first load them with potential energy 41

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Exercise Efficiency for Athletic Performance which it later converts to mechanical energy (Almeida-Silveira et al, 1994) The stored energy and extra neural activation from the stretch is then used to do work (Newton et al, 200 I). Plyometric programs come in many varieties and can be tailored to the needs of the athlete. Athletes who require powerful acceleration and high velocity jumps should incorporate plyometric jumping exercises into their training week. The NSCA descibes five types of plyometric jumping maneuvers-jumps in place standing jumps, multiple hops/jumps, box drills and depth jumps (Ebben 2007) Jumps in place consist of jumping straight up into the air and back in the same place. tanding jumps comprise of a single jump in the horizontal or vertical plane with ample time in between repetitions Multiple hops/jumps or multiples are exactly what their name implies. Multiples can be several long jumps in a row, multpile jumps over a cone or bounding over successive hurdles. Box jumps can take different variations but all include jumping onto a box or elevated level surface. Depth jumps involve stepping or jumping off of an elevated surface or box. Each ofthese categories consist of various exercises and can all be used in one or more plyometric programs. The order in which they can be executed does not matter, especially in the long term. What does matter is the speed of progression as the training program continues Progression is an important concept in exercise. It prevents th e body from adapting to the training stimuli and in do i ng so, prevents plateaus and lack of improvement. Plyometric programs should begin with simple, basic jumping moves and progress to more difficult exercises as athletic perfonnance improves. The same goes for the intensity of the workouts. Plyornetrics is a very t
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Exercise Efficiency for Athletic Performance intensity (Potach 2000). It is important to keep the intensity at a safe yet effective level in order to make the workout worth do i ng. he height in box jumps and depth jumps is directly correlated with the intensity ofthe movement. A few jumps from a high box is more intense than many small hops over a cone (Ebben, 2007). Furthermore, exercises utilizing one leg at a time increases the intensity dramatically. Adding weights to plyornetrics seems as if it would increase intensity but the extra load does not show any improvement in gains in power (de Villarreal et al, 2009). This is because the intensity is determined by the height jumped rather than the ground reaction force ( bben, 2007). Jumps are not the only type ofplyometrics training. Upper body plyometrics is available too. Medicine ball throws are the most common and incorporate the pectorals, triceps, and deltoids when performed lying horizontally on a bench (Warpeha, 2007). They can also be thrown ertically to target the shoulders for basketball and volleyball players The aforementioned bench throws mimic this horizontal plane movement but with a barbell on a Smith machine. One simple upper body plyometrics exercise is the clap pushup. This i ntense push up requires powerful pectorals to raise both hands of the ground long enough to clap:-{fthe trainee is not strong enough to perform the move on their own then they can be assisted by a spotter grabbing the bac k of their shirt and helping lift the trainee. Plyometrics is an incredibly effe ctive training scheme for athletes needing to increase their power output in jumping, agility, and acceleration. The high rate of force production comes from i ntense activation of the neuromuscular system which in turn recruits many motor units that contract maximally. Plyometrics training has also been shown to reduce injuries in the lower extremities (Hewett et al, 1996; Lim et al, 2009). Athletes should incorporate plyometrics training 1-2 times per week for improved gains in power agility, and acceleration 43

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Exercise Effic i ency for Athletic Performance Endurance E ndurance, as it relates to athleticism, is the abi l ity to keep exerting force for long periods of time. Nearly all sports require some some degree of endurance to one extent or anorher. The model endurance athlete is the triathlete. Triathlons begin with a 1500 meter swim, then a 40 kilometer bike, and finish off with I 0 kilometer run (International Triathlon Union). That's 51.5 kilometers ( 32 miles) of high intensity physical exertion. Another athlete often taughted as having incredible endurance is the elite marathon runner. The record for the fastest olympic marathon is 2 hours, 6 minutes, and 32 seconds set by the Kenyan Samuel Kamau Wanjiru (Wokabi & Mutuota, 2008). That's an average pace of 4.87 minutes per mile. Most athletes will never reach these elite endurance capabilities but they can improve their endurance to a level necessary to succeed in their sport of choice. E ndurance is a component of the musculoskeletal, cardiovascular and respiratory system It can be described in terms of aerobic endurance, anaerobic endurance speed endurance or strength endurance (Mac, 20 l 0). Aerobic endurance is defined as the ability to maintain aerobic muscle output for a long period of time (Gastelu, 2005) Anaerobic endurance is the muscle s ability to perform work under anaerobic metabolism for extended periods of time. Speed endurance is the ability to maintain muscle contractions at or higher than 85% of maximum velocity (Lee, 2007). Strength endurance is the ability to maintain contractile force for a period of time. Aerobic endurance is the focus of this review, although there are aspects of aerobic endurance that are applicable to the other types of endurance. The greatest measure of aerobic endurance is V02max-V02rnax is the maximum amount of oxygen a person can make use of during maximal exercise (Quinn, 2008). Although there is a 44

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Exercise Efficiency for Athletic Performance strong genetic determinacy for aerobic endurance (Bouchard et al 1992) it is possible for anyone to impro e it (Hartung et al 197 7) (O'Donnell et al 1998). Improvements in V02maxoccur in a decreasing scale. Untrained athletes show the greatest improvement right away with up to a 20% i ncrease (Wilmore & Costil l 2005). Beyond that, however, the increase becomes progressively les There are several methods to impro e V02ma:<: First of all, athletes can improve their endurance through their diet Several studies have hown endurance supplements such as Rhodiola ro ea extract and carbohydrate-protein drinks (De Bock et al, 2004 Ivy et al, 2003) improve endurance performance. Hydration is imperitive for performance as well. Athletes should consume l iquids before, during and after exerci e (von Duvillard et al 2004). If the exercise lasts longer than 90 minutes then a carbohydrate-electrolyte beverage should be used to replenish lost fluids (Latzk.a & Montain 1999). Furthermore, endurance trainees should be on a diet that lowers body fat. Excess body fat increases the amount of oxygen needed to fuel the muscles of ventilation and reduces the int ens ity of exercise as compared to lean body mass (Ve.lla et al, 200 8 ; Katch et al 1981; American Die te tic A sociation, 1993 ; W alberg, 1986). The second method to imp roving aero bic endurance is to increase the stroke volume of the heart. This is performed by increasing the trength of the l eft ventricle (Hambrecht et al 2000). During exercise, the heart rate increases due to sympathetic innervation. At the same time stroke volume decreases to compensate for the tachycardia (Fritzsche et al 1999) Ath l etes have higher than nonnal stroke volumes so this decrease during tachycardia is not as impac t ing as in a non-trained individual (Levine et al, 1991). Conversely, the increased stroke volume found in athletes during rest i the reason they have lower restin g heart rates (Shephard & Balady 1999) ndurance training increases stroke volume by i ncreasing myocardia l contractility which in turn 45

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Exercise Efficiency for Athletic Performance induces left ventricular hypertrophy and strength. By pumping more blood to the body per stroke, endurance trained athletes are ab le to better oxygenate their muscles and therefore, maintain a high degree of aerobic ability (Shephard & Balady, 1999). Aerobic endurance training can be any form of training which enlists cellular respiration in muscles. Cellular respiration requires oxygen to function and is the prevalent source of energy in aerobic training. Aerobic exercises include continuous or interval running, swimming, cycling and any other exercise that gets the heart beating at least at above 70% of its maximum beats per minute and for an extended period oftime. The longer the exercise beyond 75 seconds the more aerobic training being done (Gastin. 2001). Weight training can become an aerobic exercise if performed at a maximal rate but the increase in endurance may be due to improved work economy and not improvements to heart function (Hoff et al, 2002). This has been shown in 5km runners performing power training as well (Paavolainen et al, 1999). Endurance is a ubiquitous characteristic of athleticism found in sports. There are many ', ways to train for endurance and which method the athlete chooses to incorporate into their training is dependent on the requirements of their sport. A football player does not need to run a sub 5 minute mile to be successful in the National Football League and a soccer player cannot expect to excel at the elite level without a substantial degree of fitness. How much time and energy spent working on endurance is up to the athlete. Some athletes can satisfy their cardiovascular needs by participating i n sport specific training while others need to hit the track and run mile after mile. Along with training the heart, athletes can also improve their endurance by increasing the efficiency of their muscles. This can be done by performing exercises that stiffen the muscles 46

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Exercise Efficiency for Athletic Performance and elastic elements of the body through power training and eccentric strength training. Technique and posture can also affect the economy of the m()-vement so it is important for athletes to receive professional instruction in order to maximize their athletic perfonnance. Conclusion Athleticism is sometimes defined as physical prowess and is characterized by a proficiency in agility, speed, strength, power and endurance. By increasing their ability in these areas, athletes can give themselves an advantage over their opponents and, therefore, increase their chances of success in sports There are many opinions floating around about how to improve in these areas. However, some of these are backed by empirical evidence and some are not. A number of exercises have been shown to be uneffective by science yet they still circulate throughout the fitness community. It is the goal of this paper to show athletes which exercises are proven to be effective and worth incorporating into a workout regimen. Agility is the ability to change direc tio n with speed. Skills needed in agility are braking, balance spatial awareness, and acceleration. Braking can be improved by perfonning eccentric exercises which stiffens the muscles required for deceleration Balance requires good proprioception and coordination. Exercises which utilize these brain functions can serve to improve balance in athletes as effectively as training with balance boards and unstable surfaces. Therefore, it is recommended that high yield exercises such as plyometrics and functional training be performed to save time yet still satisfy the need to train the vestibular system. Spatial awareness is the awareness of what is going on in the environment. The most etTective manner to train spatial awareness is to simply participate in sport-specific practice drills or live situations. 47

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Exercise Efficiency for Athletic Performance The more deliberate a practice is, the more spatial awareness training. Acceleration is a complex maneuver and therefore, profits from a wide range of training styles. By training for strength, speed, and power an athlete can effectively train for ac.celeration. The most basic method of training for acceleration is to nm sprints and should be the first acceleration exercise attempted by less trained individuals. Speed is the amount of distance traversed in a certain amount of time and in sports it can mean a wide variety of ideas. Speed, here, is defined as the maximwn sustainable velocity There are two main qualities that must be improved for an athlete to get faster. The first is muscular capacity. Large forces are required to generate the propulsion in running. This is why strength training is recommended for speed. However, because running incorporates power and acceleration it is also recommended that athletes do power training and eccentric training once they complete the strength program. The other aspect of speed is the portion controled by the nervous system. One of the easiest ways to improve running speed is to train running at higher speeds. This is done by performing speed intervals where the athlete runs a specific distance at a faster pace than they would in a rac .e. Another method or neural enhancement is to perform technique drills which will condition the legs to be more efficient. Strength is explained as the amount of force someone is able to apply on something else. The most important concepts in strength training are overload and progression. These must be achieved to see any improvement in strength. Athletes wishing to increase their strength should start a heavy weight training program where the rep scheme is low. They should also be sure not to stretch statically beforehand as this decreases strength. Athletes who are familiar with heavy weight training and want to challenge their muscles in a very effective manner should try functional weight training. Trainees will benefit from a strengthened core and well developed 48

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Exercise Efficiency for Athletic Performance neuromuscular system primed for movements normally found in real life. Furthermore, athletes who have reached a plateau in their strength should look to shock their muscles with a negative training program. The forces created by their muscles will be greater than those performed in concentric exercise and they will see improvements in agility and power as well. Strength is a necessary foundation for power training. People who are not relatively strong should not attempt explosive maneuvers until they have a base level of strength. Power is one of the most important physical attributes in sports. Strength is important but without the ability to do work it is not effective. Speed is advantageous in athletics as well but if a person cannot accelerate quickly or generate force in the legs fast enough to run faster then speed cannot be realized. To increase power, athletes should perform explosive moves. Ballistics training and plyometrics training consist of such power moves and are very effective. However, for football players olympic lifts are the most common explosive exercises currently recommended by strength and conditioning coaches. One of the benefits of power training is that it can lead to improvements in agility, speed, and strength as well. Furthermore, by strengthening the core and neuromuscular system, it can improve balance and coordination. Endurance is necessary for any physical performance to continue for a long period of time. Without endurance, the physical gifts of athletes could not be used for more than a short interval. This is especially true in sports that require a high degree of endurance. Without aerobic endurance, sports like soccer and rugby would move much slower because players would have to slow down and catch their breath. Endurance training consists of raising the heart rate to above 70% of the maximum heart rate for an individual. How this is done is up to the athlete. In most 49

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Exercise Efficiency for Athletic Performance cases a variety of methods is recommended to avoid plateaus and boredom. Trainees can cycle run swi m row or even just skip rope. The more intense the workout, the greater the results. Training must last longer than 75 seconds however to give time for aerobic metabolism to occur. By implementing the training strategies listed athletes can gain the most out of their body as well as their training time. Science has been able to demonstrate the validity of many exercise techniques but it has also uncovered false methods that serve no benefit to its users. Athletes should be wise to study up on what is effective and what is not. This will give them an advantage over their Jess inqui itive counterparts and if there s one thing in sports that every athlete needs it is an advantage. 50

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Exercise Efficiency for Athletic Performance Adams, K., O'Shea, J. P., O'Shea, K. L., & Climstein, M (1992}. The effect of six weeks of squat, plyometric and squat-plyometric training on power production. The Journal of Strength & Conditioning Research, 6 (1}, 36-41. Allerheiligen, B. (2003}. In-season strength training for power athletes. Strength & Conditioning Journal, 25 {3}, 23 28. Almeida Silveira, M., Perot, C., Pousson, M., & Gaube/, F. (1994). Effects of stretch-shortening cycle training on mechanical properties and fibre type transition in the rat soleus muscle. PfWgers Archiv European Journal of Physiology, 427 (3-4}, 289-294. Anderson, K., & Behm, D. G. (2005) The impact of instability resistance training on balance and stability. Sports Medicine, 35 (1}, 4353. Antonio, J., & Gonyea, W J (1993, April9}. Progressive stretch overload of skeletal muscle results in hypertrophy before hyperplasia. American Physiological Society, 1263 1271. Antonio, J., & Gonyea, W. J {1993). Skeletal muscle fiber hyperplasia. Medicine & Science in Sports & Exercise, 25 {12}, 1333-1345. Appleton, B. (n.d .). Stretching and Flexibility How to Stretch. Retrieved Apri/20, 2010, from http:jjwww.cmcrossroads.com/bradappjdocsjrecjstretchingjstretching_S htmi#SEC39 Armstrong, R., Ogilvie, R., & Schwane, J. (1983). Eccentric exercise-induced injury to rat skeletal muscle. Journal of Applied Physiology, 54 (1}, 8D-93 Asmussen, ., & Bonde Petersen, F. (2008}. Storage of elastic energy in skeletal muscles in man. Acta Physiolagica Scandinavica, 91 (3), 385-392. 51

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Exercise Efficiency for Athletic Performance Fletcher, 1., & Jones, B (2004) The effect of different warmup stretch protocols on 20 meter sprint performance in trained rugby union players. Journal of Strength and Conditioning Research, 18 {4), 885 888 Fritzsche, R. G., Switzer, T. W., Hodgkinson, B. J., & Coyle, E. F. (1999). Stroke volume decline during prolonged exercise is influenced by the increase in heart rote. Journal of Applied Physiology, 86 (3), 799 805. Gastelu, D. {2005). Don Gastelo's Sport Nutrition Guide:. Retrieved April22, 2010, from www.bodybuilding .com : http://www.bodybuilding.com/fun/sportnutrition9.htm Gostin, P (2001). Energy System Interaction and Relative Contribution During Maximal Exercise Sports Medicine, 31 {10), 725. Giddings, C., & Gonyea, W J. (2005). Morphological observations supporting muscle fiber hyperplasia following weight-lifting exercise in cats. The Anatomical Record, 233 (2), 178-195. Golln ick, P., Parsons, D., Riedy, M., & Moore, R (1983). Fiber number ond size in overloaded chic ken anterior latissimus dorsi muscle. Journal of Applied Physiology, 54 (5), 1292 1297 Gonyea, W J Sale, D. G., & Gonyea, F. B. {2004). Exercise induced increases in muscle fiber number European Journal of Applied Physiology and OccupaOonal Physiology, 55 (2}, 137-141. Gonyea, W., Ericsson, G & Bonde Petersen, F. (2008). Skeletal muscle fiber splitting induced by weight lifting exercise in cats. Acto Physiologica Scandinavico, 99 (1), 105-109. Gosgnach, S., & Guillermo M Lonuza, 5. J. (2006). V1 spinal neurons regulate the speed of vertebrate locomotor outputs. Nature, 440, 215 219. 56

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Exercise Efficiency for Athletic Performance Graves, J E., Pollock, M. L., Foster, D. B., Leggett, S. H., Carpenter, D M., Vuoso, R. M., eta/. {1990}. Effect of training frequency and specificity on isometric lumbar extension strength. Spine, 15 {6}, 504 509. Greig, M. (2009). The influence of soccer-specific activity on the kinematics of an agility sprint. European Journal of Sports Science, 9 (1}, 23-33. Gutierrez, G. M., Jackson, N. D., Dorr, K. A., Margiotta, S. e., & Kaminski, T. W. (2007} Effect of fatigue on neuromuscular function at the ankle. Journal of Sports Rehabilitation, 16, 259-306. Hakkinen, K., Mero, A., & Kauhanen, H. (1989}. Specificity of endurance, sprint, and strength training on physical performance capacity in young athletes. Journal of Sports Medicine, 29, 2335. Hakkinen, K Mero, A., & Kauhanen, H. {1989}. Specificity of endurance, sprint, and strength training on physical performance capacity in young athletes Journal of Sports Medicine, 29, 23-35. Hambrecht, R., Gielen, S., Linke, A., Fiehn, E., Yu, J Walther, C., eta/. (2000). Effects of Exercise_ Training on Left Ventricular Function and Peripheral Resistance in Patients With Chronic Heart Failure The Journal of the American Medical Association, 283 {23), 3095-3101. HarrisWarrick, R. M., & Cohen, A. H (1985}. Serotonin modulates the central pattern generator for locomotion in the isolated lamprey spinal cord. Journal of Experimental Biology, 116 {1}, 2746. Hartung, G Smolensky, M., Horrist, R., Rangel, R., & Skrovan, C. {1977}. Effects of varied durations of training on improvement in cardiorespiratory endurance. Journal of Human Ergology, 6 (1), 6168. Herbert, R. D., & Gabriel, M. {2002, August 31} Effects of stretching before and after exercising on muscle soreness and risk of injury: systematic review. BMJ, 325. 57

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Exercise Efficiency for Athletic Performance Hewett, T E Stroupe, A. L., Nance, T. A., & Noyes, F. R. {1996}. Plyometric training in female athletes. The American Journal of Sports Medicine, 24 (6), 765-773 Hoff, J., Gran, A., & Helgerud, J. (2002) Maximal strength training improves aerobic endurance performance Scandinavian Journal of Medicine & Science in Sports, 12 {5), 288 295 Holcomb, M C. {2010, February 2). How to Increase Speed Workouts. Retrieved Apri/19, 2010, from f i vestrong. com : http://www. livestrong .com/article/78751 increase speed -workouts/ Hortobagyi, T., & a/ e { 1996}. Greater initial adaptations to submaximal muscle lengthening than maximal shortening. Journal of Applied Physiology, 58 {5), 1677 1682 Hortobagyi, T Hill, J., Houmard, D., Fraser N Lambert, J., & Israel, R. (1996). Adaptive responses to muscle lengthening and shortening i n humans Journal of Applied Physiology, 80 (3), 765 772 Hiibscher, M., Zech, A., Pfeife, r K., Honsel, F Vogt, L., & Banzer W {2010) Neuromuscular trai ning for sports injury prevention : a systematic review Medicine & Science i n Sports & Exercise, 42 {3), 413 421 International Triathlon Union. (n.d.). International Triathlon Union Retrieved Apri l 22, 2010, from www. triathlon.org Ivy, J ., Res, P Sprague, R & Widzer, M. (2003) Effect of a carbohydrate prote i n supplement on endurance performance during exercise of varying intensity International Journal of Sport Nutrition and Exercise Metabolism, 13 (3), 382-395 Jones A. Nautilus bulletin 111. DeLand, FL: Nautilus Sports/Medica/Industries, 1970 Jones A. Nauti lus bulleti n 112. DeLand, FL: Nautilus Sports/Medical Industries, 1971 58

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Exercise Efficiency for Athletic Performance Wilson, G Newton, R Murphy, A., & Humphries, B. {1993} The optimal training load for the development of dynamic athletic performance Medic i ne and Science in Sports and Exercise, 25 {11}, 1279 1286 Wokabi, J., & Mutuota, M. {2008, August 08}. Focus on Athletes Samuel WANJIRU Kamau. Retrieved April 22, 2010, from www. iaaf.org : http: / /www.iaaf. arg/news/athletes/news i d = 42223 .html Zafeirid is, A., Saraslanidis P Manou, V loakimidis, P Dipfa, K & Kellis, S (2005). The effects of resisted sled pulling sprint training on acceleration and maximum speed performance Journal of Sports Medicine and Physical Fitness, 45 (3) 284 290 68


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