1. basics and background Flashcards
Total daily energy expenditure (TDEE)
- 3 groups
- resting energy expenditure (REE)
- 60-75%
- basal metabolic rate / resting metabolic rate - thermic effect of food (TEF)
- 5-10%
- possibly reduced in obesity (controversial) - Physical activity
~ 15-30%
- highly variable
difference between basic and resting metabolic rate
BMR
- strict controlled measurement conditions **
RMR
- ~10% greater than BMR
what stimulates the thermic effect of food (TEF)
protein and caffeine
factors that affect REE (resting energy expenditure)
genetics age - young > old sex - men > women (muscle mass mostly) body size - height, body surface area body composition - skeletal muscle biggest contribution (40% REE) environmental temp - cold, keep body warm diet and exercise
measuring total energy expenditure
measure heat production
direct calorimetry
- persons heat production in sealed chamber
indirect calorimetry
- measure changes in o2 consumption and/or co2
- open circuit spirometry
- “metabolic cart”
- flow meters, gas analyzers
problems with indirect calorimetry
hyperventilation
- more co2 released
airtight?
mask comfort?
RER
- what can we determine from this
respiratory exchange rate
- VCO2/VO2
- determines the substrates being oxidized
VO2 use to calculate energy expenditure
thermal equivalent
~5 kcal per L O2
5 kcal X VO2 (L/min) X time
*nearly the same whether burning fat or oxygen
CO2 production (VCO2) assumptions when calculating energy expenditure
assumptions
- source of co2 production is mitochondrial
- steady state conditions are present
- otherwise co2 not completely from fat or carb oxidation
what are non-steady state conditions
- co2 production that results
hyperventilation
- increases Vco2 production
recovery from intense exercise
- decrease Vco2
RER carb vs fat
pure carb = 1
pure fat = 0.7
what influences fuel utilization
at rest
- fat use
- low energy expenditure
- no need to quickly replace ATP
- enough time for lipolysis/beta oxidation
- not fat exclusively (some cell/tissues need glucose)
- 85% fat / 15% carb
what is VO2 max
- maximum oxygen consumption and aerobic capacity
- standardized progressive test
- VO2 plateau
- general indicator of aerobic fitness
- L/min or ml/kg/min
VO2 max typical numbers
- minimum
- average 50th percentile
- superior 90th percentile
- well trained
- highest elite
(men / women - ml/kg/min)
minimum - 35 / 32.5 average - 40-45 / 35-40 superior - 54+ / 47+ well trained - 60+ / 50+ highest elite - 90+ / 80+
oxygen supply vs oxygen demand
supply
- transport of O2 from lungs to mitochondria
demand
- rate at which mitochondria can reduce O2 in oxidative phosphorylation