Sport Performance and Body Composition

The following is an exclusive excerpt from the book NSCA's Guide to Tests and Assessments, published by Human Kinetics. All text and images provided by Human Kinetics.

Sport performance is highly dependent on the health- and skill-related components of fitness (power, speed, agility, reaction time, balance, and Body Composition coordination) in addition to the athlete’s technique and level of competency in sport-specific motor skills. All fitness components depend on body composition to some extent. An increase in lean body mass contributes to strength and power development. Strength and power are related to muscle size. Thus, an increase in lean body mass enables the athlete to generate more force in a specific period of time. A sufficient level of lean body mass also contributes to speed, quickness, and agility performance (in the development of force applied to the ground for maximal acceleration and deceleration). Reduced nonessential body fat contributes to muscular and cardiorespiratory endurance, speed, and agility development. Additional weight (in the form of nonessential fat) provides greater resistance to athletic motion thereby forcing the athlete to increase the muscle force of contraction per given workload. The additional body fat can limit endurance, balance, coordination, and movement capacity. Joint range of motion can be negatively affected by excessive body mass and fat as well, and mass can form a physical barrier to joint movement in a complete range of motion. Thus, athletes competing in sports that require high levels of flexibility benefit from having low levels of body fat.

The demands of the sport require that athletes maintain standard levels of body composition. Some sports require athletes to be large in stature, mass, or both, whereas some athletes prosper when they are small in stature. For example, linemen in American football and heavyweight wrestlers need high levels of body mass. Although lean body mass is ideal, these athletes can benefit from mass increases in either form (fat included). Greater mass provides these athletes with more inertia, enabling them to play their positions with greater stability provided speed and agility are not compromised. Strength and power athletes such as American football players, wrestlers, and other combat athletes; powerlifters; bodybuilders; weightlifters; and track and field throwers benefit greatly from high levels of lean body mass. Endurance athletes such as distance runners, cyclists, and triathletes benefit greatly from having low percent body fat. Athletes such as gymnasts, wrestlers, high jumpers, pole vaulters, boxers, mixed martial artists, and weightlifters benefit greatly from having a high strength-to-mass (and power-to-mass) ratio. Training to maximize strength and power while minimizing changes in body mass (and keeping body fat low) is of great value to these sports. Gymnasts, pole vaulters, and high jumpers have to overcome their body weights to obtain athletic success. Thus, minimizing changes in mass enables greater flight height, time, and aerial athleticism.

Wrestlers, boxers, mixed martial artists, powerlifters, and weightlifters compete in weight classes. Because higher weight classes may denote more difficult competition, these athletes benefit from improving strength and power while maintaining their normal weight class. Athletes such as baseball and softball players benefit from increased lean body mass and reduced body fat. The additional lean mass can assist in power, speed, and agility, and keeping body fat low assists with endurance, quickness, speed, and agility as well (for performing skills such as throwing, hitting, fielding, and base running).

Basketball and soccer are two of several combination anaerobic and aerobic sports in which athletes need power, speed, quickness, agility, and strength yet also moderate to high levels of aerobic fitness. Athletes from both of these sports benefit from having low body fat while maintaining or increasing lean body mass. Although some athletes can tolerate higher levels of body mass and perhaps percent body fat, it is generally recommended that data obtained from frequent body composition measurements be used to develop training plans aimed at reducing body fat while maintaining or increasing lean body mass.

Developed by the National Strength and Conditioning Association (NSCA), this comprehensive text offers extensive information on performance-related assessment and testing for strength and conditioning professionals in measuring key fitness components. The book is available in bookstores everywhere, as well as online at the NSCA Store.