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Energy and Metabolism

Terms in this set (36)

types of energy
mechanical, electrical, heat chemical, nuclear, solar
energy transformation
the process of changing one form of energy to another
-in human body, converting chemical to electrical to mechanical energy (ATP to AP and muscle contraction)
bioenergetics
transfer of energy in biological organisms
-chemical energy: stored nutrients
-electrical energy: nerve impulses
-heat energy: produced by reactions, maintains body temp
-mechanical energy: used to drive muscle contraction so we can do work
Ergometry
science of measuring work
-W = f x d
ergometer
Device used to measure work
-step ergometer
-cycle ergometer
-arm crank
-treadmill
Power equation
P = w / t
-athletic component
Metabolism
sum of all chemical reactions that sustain life
-catabolic and anabolic reactions
Calorimetry
quantifies heat release from metabolic reactions.
-combustion of a known substance will result in a specific amount of energy, some of which is heat.
-heat production is proportional to # and rate of reaction
entropy
unusable energy
-expressed through heat
muscle contraction efficiency
25% efficient
Assessing Energy Expenditure
-direct calorimetry
-indirect calorimetry
-doubly-labelled water
-questionnaires & prediction equations
-food calorimeter
-metabolic chamber
-bomb calorimeter
indirect calorimetry
collecting respiratory gases
-VCO2/VO2: can give fairly accurate idea of energy sources fat vs carbs (not good for protein)
Fat: 7/10
Carbs: 1/1
direct calorimetry
measurement of heat production as an indication of metabolic rate
-food calorimeter
-metabolic chamber
-bomb calorimeter
doubly labeled water
water isotope eliminated from body allows for estimation of CO2 production and then convert to energy expenditure (EE)
calorie
amount of energy needed to raise temperature 1 mL of water by 1 degree C
kilocalorie (kcal)
the amount of energy needed to raise 1 L of water by 1 degree C
Kcal to kJ
1 kcal = 4.62 kJ
Energy Content in Food
1 g of...
-CHO = 4kcal
-fat = 9kcal
-protein = 4kcal
-alcohol = 7kcal
-These are used to produce ATP
Energy Systems of Body
choice of system dependent on duration and intensity of activity, as well as availability of oxygen
ATP/PCr System
Immediate energy system
-phosphocreatine may be effectively supplemented
Lactic Acid System
Short term energy system
-decreases pH and results in rapid fatigue
Oxygen System
Long term energy system
-requires oxygen to be adequately delivered
Energy Balance Equation
E in = E out
-energy balance
E in > E out
- positive energy balance (wt gain)
E in < E out
-negative energy balance (wt loss)
Components of TDEE
Total Daily Energy Expenditure
-Basal metabolic rate
-Thermic effect of food
-Unstructured PA
-Structured PA
BMR
basal metabolic rate
-energy required for basic, essential body processes
>50% of DEE
active: 40% of DEE
sedentary: 60% of DEE
RMR
resting metabolic rate: 5-10% > than BMR, MR at rest.
thermic effect of food
energy used to digest, absorb, and metabolize food nutrients
-10% of DEE (daily energy expenditure), but diet dependent
-protein: highest thermic effect
fat: lowest thermic effect
-trained have lower TEF than untrained
Unstructured PA
NEAT (non-exercise activity thermogenesis)
Structured PA
exercise
-people who do more exercise do less NEAT
Thermic Effect of Activity
Variable dependent on activity level
-50% in active
-20-30% in sedentary
Factors affecting BMR: Age
-BMR declines approx 2% per decade after 20
-body comp: lean vs stocky
-stocky has lower BMR due to less surface area to weight, therefore less heat loss due to radiation as compared to lean and tall
Factors affecting BMR: gender
Males have more FFM (fat free mass), higher RMR
-Females: menstrual cycle timing
Factors affecting BMR: genetics
Type I vs. Type II muscle fibers
Factors affecting BMR: PA
-greater FFM in athletes
-acute bout of exercise leads to EPOC
-muscle damage to protein synthesis requiring EE
Other factors affecting BMR
smoking, caffeine, environmental extremes
METS
metabolic equivalents: amount of O2 consumed per kg of BW per min
-1 MET = 3.5 mL O2 / kg x min
-1L O2 = 5kcals
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