OPTIMAL BODY WEIGHTFOR PERFORMANCE, FITNESS and

WELL BEING

Learning Objectives

Find out what tissues of the body constitute fat-free mass.

Discover how densitometry and several field techniques are used to assess body composition.

Examine the relationship of relative leanness and fatness to performance in sport.

Body Composition

There are several different models for measuring body composition. The two compartment model is the most common, and the simplest and easiest forms of mearuing body composition can measure only fat mass, and fat free mass

MODELS OF BODY COMPOSITION

Fat mass and Fat Free and Lean 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.

Body fat in almost every cell

Keep in mind that there is some body fat in almost every cell in your body. You’ll find tiny amounts of lipid in the cell structures of almost every cell, and covering the nerves in your brain and other places!.

Did You Know…?

Body composition is a better indicator of fitness than body size and weight. Being overfat (not necessarily overweight) has a negative impact on athletic performance and health. 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.

And

Body composition is a better indicator of fitness than body size and weight. Being overfat (not necessarily overweight) has a negative impact on athletic performance and health. 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.

Android Obesity - Apple shaped Gynoid Obesity = Pear Shaped

Android vs Gynoid Obesity

Android obesity is excess fat carried in the torso, and more common in men

Gynoid obesity is excess fat at/near the hips and is more common in women

Android obesity is more highly associated with obesity related disease such as heart attack, high blood lipid levels, diabetes, and more

While obesity is never a good thing, android obesity is worse than gynoid obesity

Simple Methods of assessing body type/build

WHR = Waist circumference/hip circumference

F >.80 =high risk M > .91 high risk

F<.73 = low risk M < .85 low risk

BMI Body Mass Index

Weight(kg) height in Meters Squared

>25 = overweight

>30 = obese

Waist to Hip Ratio and BMI are NOT methods of measuring body composition

These methods do not measure body composition, but are attempting to guesstimate body fatness

These methods work well when the goal is to measure a large population, but do not work well for individuals

The primary advantages of these methods is they are non-invasive, they require no specialized equipment, and that they can be done quickly

Assessing Body Composition

Densitometry (hydrostatic weighing)

Skinfold fat thickness

Bioelectric impedance

Densitometry

Body density = Body mass Body volume

Body mass = measured on a regular scale

Body volume = measured using hydrostatic (underwater) weighing accounting for water density

and air trapped in lungs

Underwater weighing

The two men on the next slide are the same weight and height, but different body compositions. Note what is different about them.

UNDERWATER WEIGHING TECHNIQUE

Did You Know…?

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. As well as inaccuracies in measuring the air trapped in the lungs

The next slides are photos of actual underwater weighings taking place

BIA bioelectric impedance analysis

Very Small voltage transmitted through the body

Resistance is measured

The gives total body water

FFM is repeatedly shown to be 73% water, so FFM can be calculated, and the rest is fat

Assumptions:

The body is a perfect cylinder

Participant is properly hydrated

Common Skinfold Sites

3 site equation is just as accurate as seven site equation

For Women: Triceps, Iliac Crest, Thigh

For Men: Chest, Abdomen, Thigh

Add together the sum of the skinfolds and insert into an equation such as the Jackson and Pollock equation.

This gives density, not BF.

Then Use Siri or Brozek to determine %BF

females:Body Density = 1.0994921 - 0.0009929*sum + 0.0000023*sum2 - 0.0001392*age (Sum of Skinfolds)

Males:Body Density = 1.1093800 - 0.0008267*sum + 0.0000016*sum2 - 0.0002574*age (Sum of Skinfolds)

Jackson and Pollock generalized 3 site equations. You are not expected to know these equations

What % body fat is typical?The American College of Sports Medicine has a great chart on body fate percentages for women. Note that above average, is a lower body fat, meaning above average leanness

What % body fat is typical?

.. As well as a chart for men.

Take home message for body composition

Body composition measurements are simple estimates, and none of them are really very accurate. They give you a general idea of the level of fatness, but not an exact number

What these methods are great for is measuring change. As long as all of the rules are followed these methods are great at telling you if you have become leaner or fatter.

But as far as absolute fatness, they are really just an educated guess

Body Composition and Performance

Maximizing fat-free mass

Desirable for strength, power, and muscular endurance

Undesirable for endurance or jumping sports if result is a gain in weight

Minimizing relative body fat

Desirable, especially in sports in which the body weight is moved through space

Improves speed, endurance, balance, agility, and jumping ability

RELATIVE BODY FAT IN ELITE RUNNERS

Risks With Severe Weight Loss

Dehydration

Chronic fatigue

Disordered eating and eating disorders

Menstrual dysfunction

Bone mineral disorders

Appropriate Weight Guidelines

Maximize performance within the specific sport

Are based on body composition

Emphasize relative body fat rather than total body mass

Use a range of relative fat values that are considered acceptable for the athlete’s age and sex

Endurance may have body fat as low as 5-6% ( 3-4% higher for women)

Non- Athletes…..it depends on who you ask. See the ACSM charthttp://tinyurl.com/acsmfat

Achieving Optimal Weight

Combine proper diet with exercise.

Lose no more than 0.5 to 1.0 kg (1 to 2 lb) per week.

Reduce caloric intake to 200 to 500 kcal less than daily energy expenditure.

Use moderate resistance and endurance training.

Negative Energy Balance

A negative Energy Balance is required for weight loss

1 lb of fat = 3500 Calories

Weight loss is a simple equation. Calories in must be less than calories expended. The only way for a diet to work is for there to be a negative calorie balance. Your text explains this very well.

How Many Calories in a lb of fat