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C H A P T E R 14

C H A P T E R 14. BODY WEIGHT, BODY COMPOSITION, AND SPORT. w Examine the relationship of relative leanness and fatness to performance in sport. (continued). Learning Objectives. w Differentiate among body build, body size, and body composition.

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C H A P T E R 14

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  1. C H A P T E R 14 BODY WEIGHT, BODY COMPOSITION, AND SPORT

  2. w Examine the relationship of relative leanness and fatness to performance in sport. (continued) Learning Objectives w Differentiate among body build, body size, and body composition. w Find out what tissues of the body constitute fat-free mass. w Discover how densitometry and several field techniques are used to assess body composition.

  3. Learning Objectives w Find out what guidelines best determine an athlete's goal weight. w Learn why athletes should avoid crash dieting or fixating on a weight that is too low. w Find out how much weight an overweight athlete can lose per week to maximize fat loss and minimize fat-free mass loss.

  4. Body build is the form or structure of the body. w Muscularity (mesomorphy) w Linearity (ectomorphy) w Fatness (endomorphy) Body composition refers to the proportional make-up of the body. Body Build, Size, and Composition Body sizeis determined by height and weight.

  5. MODELS OF BODY COMPOSITION 45% 60% 20%

  6. Fat-Free Mass Versus Lean Body Mass Fat-free mass is composed of all of the body's nonfat tissue including bone, muscle, organs, and connective tissue. Lean body mass includes all fat-free mass along with essential fat. Lean body mass is difficult to measure so the fat mass/fat-free mass model is most often used.

  7. Body Composition Body composition is a better indicator of fitness than body size and weight. Being over-fat (not necessarily overweight) has a negative impact on athletic performance. Standard height-weight tables do not provide accurate estimates of what an athlete should weigh because they do not take into account the composition of the weight. An athlete can be overweight according to these tables yet have very little body fat.

  8. Assessing Body Composition w Densitometry (hydrostatic weighing) w Dual-energy X-ray absorptiometry w Air plethysmography w Skinfold fat thickness w Bioelectric impedance

  9. Densitometry w Body density = Body mass Body volume w Body mass: measured on a regular scale • Body volume: measured using hydrostatic (underwater) weighing accounting for water density and air trapped in lungs • Archimedes’ principle: a body immersed in water is buoyed up with a force equal to the weight of the water displaced • % body fat = (495 ÷ body density) – 450 • Density of water = 1.00 g/ml; muscle = 1.10 g/ml; fat = 0.901 g/ml

  10. Densitometry Inaccuracies in densitometry are due to variation in the density of the fat-free mass from one individual to another. Age, sex, and race affect the density of fat-free mass.

  11. DUAL-ENERGY X-RAY ABSORPTIOMETRY (DXA)

  12. AIR PLETHYSMOGRAPHY

  13. MEASURING SKINFOLD FAT THICKNESS

  14. BIOELECTRIC IMPEDANCE TECHNIQUE

  15. Maximizing fat-free mass w Desirable for strength, power, and muscular endurance w Undesirable for aerobic endurance or jumping sports if result is a gain in weight Minimizing relative body fat w Desirable, especially in sports in which the body weight is moved through space w Improves speed, endurance, balance, agility, and jumping ability Body Composition and Performance

  16. Subject’s level of fatness (% body fat) Performance test Low Moderate High (<10%) (10-15%) (>15%) 75-yd dash (s) 9.8 10.1 10.7 220-yd dash (s) 29.3 31.6 35.0 Standing long jumpa (ft) 23.8 22.7 20.2 Sit-ups in 2 min 43.4 41.6 36.2 Note. The men in this study were classified into three levels of fatness: low, moderate, and high. aSum of three trials. The Effect of Relative Body Fat on Selected Performance Tests in Young Men

  17. RELATIVE BODY FAT IN ELITE TRACK AND FIELD ATHLETES

  18. Risks With Severe Weight Loss w Dehydration w Chronic fatigue w Disordered eating and eating disorders Female Athlete Triad w Menstrual dysfunction w Bone mineral disorders

  19. Appropriate Weight Guidelines w Maximize performance within the specific sport w Are based on body composition w Emphasize relative body fat rather than total body mass w Use a range of relative fat values that are considered acceptable for the athlete’s age, sex, and sport/event

  20. Parameter Measure Weight 72.6 kg (160 lb) Relative fat 25% Fat weight 18.2 kg (40 lb) (weight  25%) Fat-free weight 54.4 kg (120 lb) (weight – fat weight) Relative fat goal 18% (= 82% fat-free) Weight goal 66.3 kg (146 lb) (fat-free weight ÷ 82%) Weight loss goal 6.3 kg (14 lb) Computing a Weight Goal for Performance for a Female Swimmer

  21. COMPOSITION OF WEIGHT LOSS

  22. UNDERWATER WEIGHING TECHNIQUE p. 451

  23. Edna Vicki Susan Body tissue DT % DP DT % DP DT % DP Muscle 1.065 46 0.490 1.065 41 0.437 1.065 46 0.490 Bone 1.350 17 0.229 1.350 22 0.297 1.260 17 0.214 Remainder 1.030 37 0.381 1.030 37 0.381 1.030 37 0.381 DFFM 1.100 1.115 1.085 Note. DT = density of the tissue; % = percent contribution of this tissue to the total-fat-free mass; DP = proportional density of the tissue (DT · %); DFFM = density of the fat-free mass, which is the sum of the proportional densities. Differences in the Density of Fat-Free Mass (DFFM) in Three Female Athletes

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