Body composition and performance Flashcards
what is heavier - adipose tissue or muscle? Why?
Muscle - it’s denser
What are some of the limitations of height/weight tables?
- Developed from data derived primarily from white populations
- Provide no assessment of body composition
Define overweight, overfat and obese
Overweight: body weight that exceeds some average for stature, and perhaps age. Frequently accompanies increase in body fat (not always).
Overfat: when body fat exceeds an age- and/or gender-appropriate average
Obesity: the overfat condition that accompanies a constellation of comorbidities
How do you calculate BMI (body mass index)?
Weight divided by height
Give a limitation of BMI as a body measurement?
- doesn’t give any indication of body composition or body fat distribution
- doesn’t take into account differences in race/ age/ gender etc
- numerator of the BMI equation can be affected by factors other than excess body fat, such as bone, muscle mass, and increased plasma volume induced by exercise training
- certain athletes can be mistakenly classified as overweight
Explain what essential and storage fat are
- Essential fat is necessary for normal bodily functioning
- It’s found in bone marrow, in heart, lungs, liver, spleen, kidneys, intestines, muscles, and throughout central nervous system
- Storage fat accumulates in adipose tissue or between the abdominal organs
Difference between fat free mass and lean body mass?
Lean body mass is the weight of muscles, bones, ligaments, tendons and internal organs. Since there is some essential fat in the marrow of your bones and internal organs, lean body mass includes a small percentage of essential fat.
Fat free mass is weight devoid of all fat.
What percentage essential and storage fat are the standard reference woman and man?
- Reference woman: 15% storage fat and 12% essential fat (approx 27% total)
- Reference man: 12% storage fat and 3% essential fat (15% total)
Advantage and disadvantages of bioelectrical impedance body composition testing?
Ads: simple; quick; inexpensive
Dis: variability in measurement; dependence on the hydration level of the patient. can’t use with pacemaker
Advantages and disadvantages of densitometry/ hydrostatic weighing?
- More accurate than skin fold calipers or electronic devices
- For those with pacemakers, hydrostatic testing is an alternative to electrical impedance devices
- For athletes, hydrostatic testing could underestimate real body fat percentages
- have to exhale and hold very still under water multiple times
- expensive
When thinking about body composition of athletes, what can you say about fat free mass?
- Includes muscle
– more = good for power, strength, muscle endurance
– more = bad for aerobic endurance (more mass to carry)
When thinking about body composition of athletes, what can you say about relative body fat?
- Fat: dead weight but useful energy store
- Less fat usually = better performance
- Exceptions: sumo wrestler, swimmer, weightlifter
What are four key risks of severe weight loss when athletes are trying to ‘make weight’ for competition?
- Dehydration
- Chronic fatigue
- Eating disorders
- Menstrual dysfunction
What is the ‘female athlete triad’, when referring to body composition?
- Bone mineral disorders
- Eating disorders
- Menstrual disorders
What types of muscle fibres do humans have?
Type 1 (slow oxidative): slow twitch (endurance fibres) - low levels of force but good fatigue resistance
Type 2: fast twitch
2a (fast oxidative) - good levels of force and moderate fatigue resistance
2x (fast glycolitic) - highest levels of force BUT rapidly fatigued
Name 3 types of muscle?
Skeletal; cardiac; smooth (inc blood vessels)
What can you say about type 1 muscle fibres?
- ‘slow oxidative’
- fatigue resistant – they are the endurance fibres
- rich blood supply – dense, rich supply of capillaries
- more mitochondria
- contain fat droplets
What can you say about type 2 muscle fibres?
- proportionally lower supply of blood cf type 1, although in highly trained people this can change
- good at storing fat – cf the droplets in type 1, type 2 has rich supplies of glycogen
- type 2a and type 2x. 2x is very fast and very quick to fatigue. 2a expresses some high speed properties and some fatigue resistance (humans don’t have type 2b)
Are your number of type 1 and 2 fibres fixed?
No. They can convert between types depending on use. So endurance athletes might develop more type 1
What is the unit of contraction in a muscle cell?
Sarcomere