Nutrition Chapter 14

A football player who weighs 250 lb (113 kg) is shown by the skinfold technique to have 20% body fat. He would therefore have ____________ lb (kg) of fat.

50 (or about 22.7kg)

Describe two field techniques for assessing body composition and the principles behind their operation.

BMI - using the equation, (body mass in kg) x (height in m)^2 Skinfold - finding the measurements of three skinfold sites and using the measurements in the density equations of Jackson and Pollock

Body fat might be of some benefit to swimming performance because it increases the body's _____________

Buoyancy

What is densitometry? How is it used to assess the body composition of the athlete? What is the major weakness of densitometry with respect to its accuracy?

Densitometry is the most accurate way that is used the most common to measure body composition. It test for the body density of the body composition of the athlete. The major weakness has to do with the variation of density of fat free mass from one indiviudal to another

Which of the following statements is (are) true concerning DXA? a. It can be used to estimate bone density as well as body composition (fat and fat-free mass). b. It is considered a densitometric technique. c. Measurements are made while the subject is submerged underwater. d. none of the statements are correct e. all of the statements are correct

a. It can be used to estimate bone density as well as body composition (fat and fat-free mass).

In which of the following sports would higher relative body fat (e.g., a woman who has 24% body fat vs. one who has 18% body fat) have less negative effect on performance? a. distance swimming b. track sprinting c. distance running d. swim sprinting e. high jump

a. distance swimming

DXA stands for a. dual-energy X-ray absorptiometry b. digital X-ray absorption c. direct x-ray analysis d. direct x-ray absorption e. dual x-ray analysis

a. dual-energy X-ray absorptiometry

Which of the following statements about underwater weighing is true? a. It can divide the body into bone, muscle, and fat components. b. It assumes standard densities for bone, muscle, and fat. c. It can divide the body into visceral and subcutaneous fat components. d. It is a direct method of assessing body composition.

b. It assumes standard densities for bone, muscle, and fat.

The densitometric technique to measure body density using air displacement is a. bioelectrical impedance b. air plethysmography c. air immersion d. air conduction e. bioelectrical immersion

b. air plethysography

In the densitometry method of body composition analysis, the density of the body is compared to the density of a. fat b. water c. muscle d. bone e. alcohol

b. water

The most significant problem in obtaining an accurate evaluation of a person's body composition using densitometry is a. inability to obtain an accurate weight underwater b. inaccurate assumption of the density of fat c. inaccurate assumption of the density of the fat-free mass d. none, because the technique is always highly accurate

c. inaccurate assumption of the density of the fat-free mass

Maximizing fat-free mass is desirable for athletes involved in activities a. such as endurance sports b. such as high jumping c. that require strength and muscular endurance d. such as pole vaulting e. a and c

c. that require strength and muscular endurance

Higher relative body fatness is not associated with poorer performance on tests of a. speed b. endurance c. balance d. cognitive function e. agiltiy

d. cognitive function

The Siri equation is used to convert body density to an estimate of relative percentage body fat and assumes that a. the densities of the fat mass and the fat-free mass are relatively constant in all people b. the relative density of fat is generally 1.1 g/cm3 c. the density of each tissue constituting the fat-free mass is known d. the density of each tissue constituting the fat-free mass varies by a standard and accountable amount e. a and c

e. a and c

Which of the following methods would be most suitable for assessment of body-fat content in a large-scale epidemiological study? a. bioelectrical impedance b. hydrostatic weighing c. isotope dilution d. skinfold thickness e. body mass index

e. body mass index

If a small weight loss improves a person's performance, then a major weight loss will improve performance even more. t/f

false

Imaging techniques, including magnetic resonance imaging, computed tomography, and bioelectrical impedance, can be used to visualize fat depots in the human body. t/f

false

Skinfolds are the most accurate way to measure body fat as long as the fold thickness is not converted to a percentage body fat. t/f

false

With the bioelectric impedance technique for estimating body composition, the electrical current moves through the fat tissue at a much slower rate than it does through the fat-free mass because of the lower density of the fat-free mass. t/f

false

What is the relationship of relative leanness and fatness to performance in sport

relative fatness is generally detrimental to athletic performance Relative leanness is desirable in sports that body weight is moved through space

What tissues of the body constitute the fat-free mass?

smooth, muscle, and skeletal

Air displacement plethysmography has been shown to provide reasonably precise measurements of body volume. t/f

true

Maximizing the fat-free mass of the athlete is desirable for athletes involved in activities that require strength, power, and muscular endurance. t/f

true

Body density is measured directly by a. electrical impedance b. skinfolds c. underwater weighing d. radiography

underwater weighing