Body Composition

Health Components of Fitness

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What is body composition?

Chemical makeup of the body.. split into

  • Fat mass: % of body weight stored as fat
  • Lean body mass: weight of the rest of the body (bone, muscle, organs)

Average male: 12-18 % body fat. Average female: 20-28% body fat

Elite male: 6-12% Elite female: 12-20%

  • ideal size depends on the sport and event (basketball players need to be tall)
  • Body composition is more important then body size and build as it concentrates more on % of fat tissue - athlete will try to minimise body fat
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Body composition assessment

BMI is a measure of an adult's weight in relation to their height - provides a estimate of overweight and obiesity.

  • Hydrostatic weighing: weighed underwater (difference between athletes scale weight and underwater weight is the fatt mass %)
  • (+) most commonly used
  • (-) only estimates the density of fat-free mass (varies to gender, age)
  • Bioelectrical impedance spectroscopy: Electrical currents through the body (computerises body fat % against the height and weight)
  • (-) affected by the level of hydration
  • (-) uses average populations not appropriate for elites
  • Skinfold measures: Measure in millimetres the level of fat below the skin (the sum of these are used to estimate body fat)
  • (+) most widely used
  • (+) provide a good estimate
  • (-) testers need to be properly trained
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Energy Expenditure

Overweight/obesity: Occurs as a result of an imbalance between energy intake and energy expenditure

Energy Expenditure:

  • Basal Metabolic rate is the lowest rate of energy expenditure needed essentially at rest
  • Bodys total metabolic rate: RMR (60-75%), physical activity (20-30), digestion of food (0-20%)

Metabolic equivalent task (MET's) - use o2 consumption per unit of body weight per minute to estimate exercise intensity

  • at rest your body uses approx 3.5 ml o2 per kilogram of body weight per min
  • However MET's are sometimes thought to overestimate energy expenditure
  • Amount of calories used in exercise = RMR x activitys MET rate
  • To work out RMR: x body weight by 10 + body weight and divide by 24
  • This prevents the danger of athletes from not having enough energy to fuel and to make sure it does not outweight energy expenditure
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Energy Intake

The food consumed or dietary intake

  • 10-15% protein - 494 kcal
  • no more then 30% fat - 989 kcal
  • 55-60% carbohydrate - 1813 kcal
  • If participating in aerobic activity you will require higher % of carbohydrate 
  • Athletes will consume 5000 to 6000 kcal a day to refuel the kcal required in their activity
  • You can use calorie calculators to work out dietary intake: (Weight x RMR x 24) a day .. or 90 minutes (weight x RMR x 1.5)
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