Chapter 4 Body Composition 1 How much should

1 2 3 4 Key Terms • Body composition: The fat and nonfat components of the human body; important in assessing recommended body weight • Percent body fat: Proportional amount of fat in the body based on the person’s total weight; includes both essential and storage fat • Lean body mass: Body weight without body fat • Recommended body weight: Body weight at which there seems to be no harm to human health (healthy weight) © 2010 Cengage-Wadsworth

1 2 3 4 Height/Weight Tables • First published in 1912 • Based on average weights (including shoes and clothes) for men and women who bought life insurance policies between 1888 and 1905 © 2010 Cengage-Wadsworth

1 2 3 4 Key Terms • Overweight: An excess amount of weight against a given standard such as height or recommended percent body fat • Obesity: An excessive accumulation of body fat usually at least 30% above recommended body weight © 2010 Cengage-Wadsworth

1 2 3 4 Essential and Storage Fat • Total fat in the human body can be classified into two types: • Essential fat: Minimal amount of body fat needed for normal physiological functions; constitutes about 3% of total weight in men and 12% in women • Storage fat: Body fat in excess of essential fat; stored in adipose tissue © 2010 Cengage-Wadsworth

1 2 3 4 Typical body composition of an adult man & woman •

1 2 3 4 Critical Thinking • Mary is a cross-country runner whose coach has asked her to decrease her total body fat to 7 percent. Will Mary’s performance increase at this lower percent body fat? • How would you respond to this coach? © 2010 Cengage-Wadsworth

1 2 3 4 Techniques to Assess Body Composition • More common techniques – – – Hydrostatic weighing Air displacement Skinfold thickness Girth measurements Bioelectrical impedance © 2010 Cengage-Wadsworth

1 2 3 4 Techniques to Assess Body Composition: DEXA • Research/medical facility technique – Dual energy X-ray absorptiometry (DEXA) – Uses very low-dose beams of X-ray energy – Measures total body fat, fat distribution, bone density – +-1. 8% © 2010 Cengage-Wadsworth

1 2 3 4 Hydrostatic Weighing +-. 5% © 2010 Cengage-Wadsworth

1 2 3 4 The Bod Pod, used for assessment of body composition +-2.

1 2 3 4 Anatomical landmarks for skinfold measurement +-3. 5% © 2010 Cengage-Wadsworth

1 2 3 4 Girth Measurements • Estimate body fat by measuring circumferences or “girth” measurements at various body sites • Requires a standard measuring tape • May not be valid for athletes or visually thin or obese people • Women: Upper arm, hip, and wrist measurements (cm) • Men: Waist and wrist measurements (inches) © 2010 Cengage-Wadsworth

1 2 3 4 Bioelectrical Impedance • Simpler to administer, but accuracy is questionable • Sensors are applied to the skin and a weak electrical current is run through the body to estimate body fat, lean body mass, and body water • Based on the principle that fat tissue is a lessefficient conductor of an electrical current • The easier the conductance, the leaner the individual © 2010 Cengage-Wadsworth

1 2 3 4 Determination of Body Mass Index (BMI) © 2010 Cengage-Wadsworth

1 2 3 4 Mortality risk vs. BMI • BMI is used almost exclusively to determine health risks and mortality rates associated with excessive body weight • Data indicates that disease risk starts to increase when BMI exceeds 25 • The risk also increases for individuals who are underweight (below 18. 5) © 2010 Cengage-Wadsworth

1 2 3 4 Disease Risk According to Body Mass Index (BMI) • BMI does not differentiate fat from lean body mass or note where most of the fat is located • Athletes with large amounts of muscle mass can fall into the moderate or high-risk categories © 2010 Cengage-Wadsworth

1 2 3 4 Waist Circumference • Predicts disease risk according to the where

1 2 3 4 Body Composition Classification According to Percent Body Fat • Determine

1 2 3 4 Effects of a 6 -week aerobics exercise program on body composition • Loss of lean body mass can be offset or eliminated by combining a sensible diet with physical exercise © 2010 Cengage-Wadsworth

1 2 3 4 Assessment of Blood Pressure • Blood pressure – Systolic blood pressure: Pressure exerted by blood against walls of arteries during forceful contraction of the heart – Diastolic blood pressure: Pressure exerted by the blood against the walls of the arteries during the relaxation phase of the heart – “Silent Killer” © 2010 Cengage-Wadsworth