An athlete's body composition is made up of two factors: fat mass, which includes all fat under the skin and surrounding the vital organs, and fat-free mass, which includes muscle, bone, ligament and organs. Body fat percentage is the amount of fat mass a person has in proportion to his entire body weight. Healthy body fat percentage recommendations are based on a person's age and sex, but do not take activity levels or body type into consideration, leading to inaccurate guidelines for athletes.
Meaning
The World Health Organization and the National Institutes of Health have not set standards for body composition in adults, adolescents, or children.The American College of Sports Medicine's "Guidelines for Exercise Testing and Prescription" suggest that males and females who are 20 to 29 years old average 15.9 percent and 22.1 percent, respectively. Conversely, the National Strength and Conditioning Association cites a range of 14 to 16 percent for males and a slightly higher 24 to 25 percent for females who are 18 to 25 years old. Because an athlete often reaches elite levels of competition in her late teens or in her twenties, she may think these values apply to her. However, athletes are subject to other variables that influence their body fat percentage norms.
Influencing Factors
An athlete's body undergoes demands that are different from the general population, leading to adaptations that are beneficial to his sport performance. These athletic demands, however, are specific to the sport played, and can even be specific to the position played within a sport. For example, a team of football players may have a short, stocky ball carrier whose low body fat percentage allows him to make quick movements, as well as a large, bulky lineman whose increased body fat percentage helps him overpower smaller players. Sport-specific guidelines provide a clearer picture of healthy body fat percentages in athletes.
Significance
Most sports are characterized as either endurance or power sports, though there is a spectrum of athletic demands that spans these two extremes. In their book, "Exercise Physiology," William D. McArdle, Frank I. Katch and Victor L. Katch identify six sport categories: high skill, aesthetic, weight category, endurance, ball games and power. The authors state that, based on the sport category, body fat percentage has high variability. Athletes who must constantly work against their own body weight for long periods, such as a cross-country runner, benefit from having lower percentages of body fat--less than 7 percent for males and less than 15 percent for females. For these athletes, excess body fat is excess weight and does not aid in energy production or performance. Athletes who need to generate a massive amount of force, such as a shot putter, have above-average body fat percentages: 18 to 20 percent for males and 26 to 30 percent for females.
Most athletes fall in the middle of the spectrum. Hockey players, weightlifters, rugby players, skiers and bobsledders may benefit from moderate levels of body fat, as the increased weight can aid force production without hurting speed or endurance levels. Tennis, volleyball, baseball and softball players may not derive a benefit from higher levels of body fat, but can maintain average body fat percentages without a detriment to performance. However, all of the these athletes fall into ranges that would be considered "average" or "leaner than average" in the general population. In nearly all athletes, body fat beyond moderate levels is disadvantageous and should be avoided.
Considerations
Monitoring body fat percentages can be difficult. Body weight is not an indicator of body composition, and therefore should never be used to infer body fat percentage in athletes. This is a common mistake that leads an athlete to attempt to lose weight, often to the detriment of her performance. Using skin calipers or bioelectrical impedance machines are universal and commercially available ways to estimate body fat percentage. Tracking body composition over the course of a full year will give an athlete an idea of what "normal" is to him and allow him to make positive changes that will affect his health and performance.
Expert Insight
Healthy body fat percentages in athletes are influenced by the sport, and occasionally the position within the sport, but are lower than that of the general population. The National Strength and Conditioning Association states that the vast majority of athletes fall in categories of "extremely lean," "very lean," "leaner than average," and "average" when compared to the general population. The NSCA also indicates that male athletes vary from less than 7 percent to 17 percent and female athletes from less than 15 percent to 25 percent body fat, depending on the sport. However, these are only guidelines. An athlete should work with her coaching staff and personal physician, if necessary, to determine the individual body fat percentage that will enhance both her health and her athletic abilities.
References
- "Practical Applications in Sport Nutrition"; Heather Hedrick Fink, Lisa A. Burgoon and Alan E. Mikesky; 2009.
- "ACSM's Resource Manual for Guidelines for Exercise Testing and Prescription (5th Ed.)"; Leonard A. Kaminsky, PhD.; 2006
- "Essentials of Strength and Conditioning (3rd Ed.)"; Thomas R. Baechle and Roger W. Earle; 2008
- "Exercise Physiology (5th Ed.)"; William D. McArdle, Frank I. Katch, and Victor L. Katch; 2001
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