Module 4: Anthropometric Measures and Body Composition in Athletes Flashcards
What is body composition?
- The body’s relative amounts of fat and lean body tissue (or fat-free mass-FFM)
- Best way to get an indication of athlete’s health (BMI is a screening tool NOT a diagnostic tool)
What are the components of FFM?
- Muscle
- Bone
- Water
- Organ tissues
What are the components of total body fat?
Total body fat = essential fat + storage fat
What is essential fat?
- Fat required for normal physiological function and insulative protection of major organs
- Consists of fat within:
1. Major organs
2. Muscles
3. Central Nervous System
How much of total body weight is essential fat?
- 3-5% total body weight in males
- 8-12% total body weight in females (need more to support reproduction)
- Some athletes like bodybuilders will have lower ranges
- EDs like anorexia nervosa may have encroachment into essential fat stores
How is body composition broken down by gender?
- Greater amounts of muscle and bone in men, less storage and essential fat in men
- Components relate to how RMR equations are estimated. Correct for unknown differences in body composition based on gender
What is storage fat?
- Nonessential fat stored as adipose tissue near the body’s surfface
- The component people are looking at reducing when they “want to lose weight”
- More storage fat in some sports may provide benefit, need to look at sport athlete is in and what is needed for it
What is Percent Body fat (%BF)?
- Percentage of total body weight represented by fat
- Primary index used to evaluate body composition
- Several methods are available to estimate body fat levels with varying accessibility and accuracy
- Indirect measurements, short of doing an autopsy will never know exact amounts
- Can provide a good way to see how athlete is changing based on recommendations/health
What is fat free mass (FFM)?
- Body mass minus all extractable fat
- FFM = Body Mass - Fat mass (%BF x BM)
How can you measure effectiveness of change?
Repeated body composition measures to show how things have changed rather than just a snapshot
What are the purposes of evaluating body composition?
- To help assess health risks and determine needed behavior changes for optimal health
- To help athletes determine the best body composition for performance in their respective sport
→ No distinct cut offs, anecdotal evidence of top performers but can still have success even if body composition isn’t normative (e.g. Yamamoto)
What are the effects of excessive body fat?
- Can increase risk of chronic disease such as:
- CVD
- Type 2 diabetes
- Hypertension
- Cancer
What are the effects of low levels of body fat?
- Extremely low levels can result in reproductive, circulatory, and immune disorders and are associated with RED-S and malnutrition
What are the common methods for assessing body composition?
- height, weight, BMI
- Waist-to-hip ratio (and body girth measurements)
- Skinfold measurements
- Hydrostatic (underwater) weighing
- Air displacement plethysmography (e.g. BodPod)
- Bioelectrical impedence analysis (BIA)
- Dual-energy X-ray absorptiometry (DXA)
What are the types of assessment models?
- two compartment - FM and FFM
- three compartment - Fat, LM, Bone
- 4 compartment - bone, water, protein, fat
What are the methods of assessing height?
- Best measured using a stadiometer
- Ensure the subject removes shoes, stands straight up with heels together, holds deep breath during measurement
What are the methods of assessing body weight/mass?
- Best measured on a calibrated scale at set time of day
- Ensure the subject removes shoes, wears minimal clothing (if nude weight is not possible)
- BW = pounds
- BM = kg (1kg = 2.2lbs)
- Never weigh in a group and only weigh if it is necessary, have consent, and can tell them they do not have to look
What is Body Mass Index?
- Based on the concept that a person’s weight should be proportional to height
- Used to estimate degree of obesity in large populations
- Does not take into account % of fat or FFM (not very useful measure for athletic populations)
- BMI = BM (kg) / height (m2)
- Population screening tool, not diagnostic!
- Not appropriate for use in populations like pregnancy, elderly population, athletes)
What is waist-to-hip ratio?
- Provides evaluation of body fat distribution
- Waist circumference: should be measured at the narrowest point below the rips
- Hip circumference: should be measured at the widest point (around the gluteus maximus)
- Depends upon skill of tester and being able to hit landmarks
- Can then use girth/circumference to estimate %BF by using equations
What are skinfold measurements? Are they accurate?
- Highly correlated (if done correctly) with other methods of measuring %BF (including DEXA and hydrostatic weighing)
- Multiple sites are measured and %BF is calculated using the sum of the sites (3 site, 4 site, 7 site methods)
- Measurements should be taken on the R side of body
- Accuracy is predicted on the skill and experience of the tester
What is hydrostatic weighing?
- Also known as underwater weighing
- Historically the most commonly used lab technique for measuring %BF
- Uses whole-body density to calculate body comp based on Archimedes’ principle (fat more buoyant than lean tissue)
- Cons: time consuming, not feasible to test large number of athletes, and methodology may not be comfortable
What is air dysplacement plethysmography?
- calculates %BF from body density (similar to hydrostatic weighing)
- Uses computerized air pressure sensors to determine amount of air displaced (rather than water)
- Bod pod device used for this method
- May be claustrophobic, hard to get repeat measures
What is bioelectrical impedence analysis and its cons?
- Rapid, non-invasice, and inexpensive method of measuring body comp
- Sends electrical current through the body to estimate body fat (based on principle that fat is less conductive than lean tissue)
- Cons: possesses a higher degree of measurement error (measurements may be affected by subject’s hydration status)
- More widely available
- Need water for current and will overestimate BF if dehydrated
- Accuracy not as important if only looking at change in numbers
What is dual energy x-ray absorptiometry (DEXA)?
- Uses a series of low-dose, transverse radiation scans, providing high degree of accuracy and regional analysis
- Provides measurements of bone mineral, fat, and nonbone lean tissue (able to measure visceral fat as well)
- Cons: expensive, need equipment, testing staff
- Not as practical for sport, done for a specific purpose or screening
Compare and contrast the different assessment methods. What are the pros and cons of each?
What are the BMI ranges?
What are the waist-to-hip ratio norms?
A trainer believes that all sports should have low body fat? What would you say to them?
- Different body types are seen in different sports and can provide advantages
- Depending on sport there may be a body type and thus body fat associated
- Some athletes naturally have the body type needed and some athletes will have to change. By no means is it a be all end all
What are the fitness categories for %BF for Men and Women of varying ages?
What factors need to be considered when assessing body composition in athletes?
- Needs/goals of the athlete (e.g. an athlete looking to increase lean mass)
- The most appropriate method for your situation, based on:
- the resources (time, cost, etc) and equipment available to you
- Validity, accuracy, and reliability of methods
- Ability to obtain serial/repeated measures
Why are body fat measurements important in terms of nutrition and training?
- Body composition does not directly determine performance, however, it may be relevant to measure depending on the athlete/sport type
- Measurements can be used to help inform appropriate training and nutrition strategies for fat loss and muscle gain
- Training and nutrition have to be married to see composition changes
What are challenges of assessing body composition?
- Method and accessibility
- How to interpret the results
- Deciding whether to make body composition changes and if so what the body composition goal should be
- How to alter body composition with training and nutrition
What are the challenges to changing body composition for athletes?
- Athletes are already active and increasing activity levels/training to create an energy deficit may not be an option
- Limiting energy intake is risky → may not have enough calories to fuel performance
- Eating disorders are common in some sports and the risk of promoting or worsening a an eating disorder must be mitigated
- Athletes are busy and lack time and skills to plan meals, prepare foods, and eat structured meals
- There is variation, by sport, in what is considered an optimal weight
- Should not change body composition in the middle of the season
- Genetic influences
- Expectations may not match what is reasonably possible in terms of time required, magnitude of results, impact on performance
- Futile cycles