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-free mass.
200 lb (or 90-91 kg)
Generally, excessive body fat impairs athletic performance in activities in which body mass must be moved through space. Which of the following is an exception to this fact? -heavy weightlifters who increase body fat before competition to gain a mechanical advantage by lowering the center of gravity -sumo wrestlers -swimmers, because body fat improves buoyancy and decreases drag -All statements are correct.
All statements are correct.
Which of the following is false? -BMI is calculated as weight (in kilograms) squared divided by height (in centimeters). - BMI provides useful information about risks for various diseases and is used in many epidemiological and clinical studies. - BMI correlates with the incidence of cardiovascular complications (hypertension and stroke). - BMI is best used for populations rather than individuals. - BMI is best combined with waist circumference or body composition measurements.
BMI is calculated as weight (in kilograms) squared divided by height (in centimeters)
What tissues of the body constitute the fat-free mass?
FFM includes water, protein, mineral (bone and soft tissue mineral), glycogen, muscles and organs
The Siri equation is used to convert body density to an estimate of relative percentage body fat and assumes that -the densities of the fat mass and the fat-free mass are relatively constant in all people -the relative density of fat is generally 1.1 g/cm3 -the density of each tissue constituting the fat-free mass is known -the density of each tissue constituting the fat-free mass varies by a standard and accountable amount - a and c
a and c
Which of the following methods would be most suitable for assessment of body-fat content in a large-scale epidemiological study? - bioelectrical impedance -hydrostatic weighing -isotope dilution -skinfold thickness - body mass index
body mass index
Body fat might be of some benefit to swimming performance because it increases the body's _____________.
bouyance
A center fielder of a major league baseball team is 188 cm (6 ft 2 in.) tall and weighs 81 kg (180 lb). Is he at his ideal playing weight? - yes - no, too light -cannot be accurately determined from the information provided - no, too fat
cannot be accurately determined from the information provided
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? -distance swimming -track sprinting -distance running -swim sprinting -high jump
distance swimming
DXA stands for - dual-energy X-ray absorptiometry -digital X-ray absorption - direct X-ray analysis -direct X-ray absorption - dual X-ray analysis
dual-energy X-ray absorptiometry
Which of the following is incorrect concerning bioelectrical impedance? -Electrical conduction through the tissues between electrodes depends on the water and electrolyte distribution in that tissue. -Electrical conductivity is much greater in the fat mass than in the fat-free mass. - The amount of current flow through the tissues reflects the relative amount of fat contained in that tissue. -The relative body fat in lean athletic people tends to be overestimated with bioelectrical impedance because of the nature of the equations used.
electrical conductivity is much greater in the fat mass than in the fat-free mass
T/F If a small weight loss improves a person's performance, then a major weight loss will improve performance even more.
false
T/F Imaging techniques, including magnetic resonance imaging, computed tomography, and bioelectrical impedance, can be used to visualize fat depots in the human body.
false
T/F Skinfolds are the most accurate way to measure body fat as long as the fold thickness is not converted to a percentage body fat.
false
T/F 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.
false
The most significant problem in obtaining an accurate evaluation of a person's body composition using densitometry is - inability to obtain an accurate weight underwater -inaccurate assumption of the density of fat - inaccurate assumption of the density of the fat-free mass -none, because the technique is always highly accurate
inaccurate assumptions of the density of the fat-free mass
Which of the following statements about underwater weighing is true? - It can divide the body into bone, muscle, and fat components. -It assumes standard densities for bone, muscle, and fat. -It can divide the body into visceral and subcutaneous fat components. -It is a direct method of assessing body composition.
it assumes standard densities for bone, muscle, and fat
Which of the following methods would you use in a large-scale study to assess body composition? -skinfold thickness -hydrostatic weighing (underwater weighing, or hydrodensitometry) -air displacement plethysmography (Bod Pod) -bioelectrical impedance analysis (BIA) -dual-energy X-ray absorptiometry (DXA)
skinfold thickness
Maximizing fat-free mass is desirable for athletes involved in activities -such as endurance sports -such as high jumping -that require strength and muscular endurance -such as pole vaulting - a and c
that require strength and muscular endurance
T/F Air displacement plethysmography has been shown to provide reasonably precise measurements of body volume.
true
T/F Maximizing the fat-free mass of the athlete is desirable for athletes involved in activities that require strength, power, and muscular endurance.
true
Body density is measured directly by -electrical impedance -skinfolds -underwater weighing -radiography
underwater weighing
___________________________ is currently considered the most accurate method for assessing body composition, even though it is known to have serious limitations.
underwater weighing
In the densitometry method of body composition analysis, the density of the body is compared to the density of - fat -water - muscle - bone -alcohol
water
Some of the error in estimating body fatness from body density measurements is related to the variability in the density of -water -the fat mass -the lean mass -subcutaneous fat components -extracellular fluid
water