CSSD Body Composition 5 — Questions and Answers
Question 1: A CSSD uses DXA to assess a 55-year-old masters female triathlete. Which body composition change is most expected compared to her values at age 30?
- Increased bone mineral density due to decades of weight-bearing exercise
- Decreased lean mass and increased fat mass even with maintained exercise habits (Correct answer)
- No significant change in body composition if training volume is preserved
- Increased total body water percentage due to hormonal changes
Correct answer: Decreased lean mass and increased fat mass even with maintained exercise habits
Sarcopenia (age-related muscle loss) and hormonal changes with menopause lead to decreased fat-free mass and increased fat mass, even in athletes who maintain training, making body composition monitoring important in masters athletes.
Question 2: A sports dietitian notices that a male cyclist's skinfold sum has increased 10 mm over 6 weeks despite maintained training. The most appropriate next step is:
- Immediately place the athlete on a caloric restriction protocol
- Assess energy intake, training load changes, and stress or recovery status before making dietary changes (Correct answer)
- Repeat the skinfolds with a different caliper brand to confirm the result
- Attribute the change to skinfold measurement error and take no action
Correct answer: Assess energy intake, training load changes, and stress or recovery status before making dietary changes
A meaningful increase in skinfold sum warrants a full assessment of diet, training, sleep, and stress before intervening, as multiple factors can drive fat gain and nutrition changes should be evidence-based.
Question 3: Which of the following best explains why athletes from African American backgrounds may have DXA body fat estimates that are lower than their actual fat mass?
- DXA software is calibrated using European reference populations with lower bone mineral density (Correct answer)
- African American athletes have lower skeletal muscle mass on average
- DXA overestimates lean mass in all dark-skinned individuals
- The two X-ray beams cannot penetrate denser skin pigmentation accurately
Correct answer: DXA software is calibrated using European reference populations with lower bone mineral density
DXA reference equations were largely derived from European populations; African American individuals tend to have higher bone mineral density, causing DXA to over-attribute tissue to lean mass and underestimate fat mass.
Question 4: In the context of sport, what does 'percent body fat at which performance is optimized' most accurately reflect?
- The absolute lowest body fat percentage achievable without losing lean mass
- The individualized fat level at which power-to-weight ratio and health markers are both favorable (Correct answer)
- A universally agreed-upon target published in sport-specific governing body guidelines
- Body fat percentage at which the athlete's BMI falls in the 'normal' range
Correct answer: The individualized fat level at which power-to-weight ratio and health markers are both favorable
Optimal performance body fat is highly individual and sport-specific; it represents the balance point where power-to-weight or strength-to-weight ratio is maximized without compromising health or hormonal function.
Question 5: Which equation is most appropriate for estimating percent body fat from body density in lean, highly trained male athletes?
- Siri (1956) two-compartment equation assuming FFM density of 1.1 g/cc
- Lohman (1986) equation for children and adolescents
- The Durnin-Womersley equation developed for sedentary adults
- A population-specific equation validated in athletes, such as the Withers or Modlesky equation (Correct answer)
Correct answer: A population-specific equation validated in athletes, such as the Withers or Modlesky equation
Athlete-specific conversion equations account for the higher bone mineral density and lower total body water percentage in elite athletes, producing more accurate body fat estimates than general population equations.
Question 6: A collegiate wrestling program implements the NCAA Minimum Weight Certification Program. What is the primary body composition criterion used to establish an athlete's minimum competition weight?
- Body weight cannot fall below 95% of pre-season body weight
- Athletes must maintain a body fat percentage no lower than 5% for males and 12% for females
- Minimum weight is set at the athlete's weight when body fat reaches 7% (males) or 12% (females) (Correct answer)
- Minimum weight equals current weight minus the maximum allowable dehydration loss
Correct answer: Minimum weight is set at the athlete's weight when body fat reaches 7% (males) or 12% (females)
The NCAA minimum weight certification uses 7% body fat for males and 12% for females as the floor; the weight at which the athlete would reach that threshold is their certified minimum competition weight.
Question 7: A CSSD is counseling a Paralympic powerlifter with a lower-limb amputation about body composition assessment. Which consideration is most important?
- Standard skinfold equations are valid because amputation does not affect trunk fat distribution
- Standard two-compartment equations are invalid because amputation alters the assumed relationship between body density and fat mass (Correct answer)
- DXA is contraindicated for athletes with prosthetics due to radiation risk
- BIA is the preferred method because limb absence does not affect electrical pathways
Correct answer: Standard two-compartment equations are invalid because amputation alters the assumed relationship between body density and fat mass
Amputation changes the proportions of bone, muscle, and fat relative to total body weight, violating the assumptions embedded in standard 2-compartment body density equations; athlete-specific or multicompartment approaches are recommended.
CSSD Body Composition 5
A CSSD uses DXA to assess a 55-year-old masters female triathlete.
Which body composition change is most expected compared to her values at age 30?