basics of exercise metabolism

Question 1

Bioenergetics

Answer 1

study of how energy is transformed through biochemical rxns

Question 2

Metabolism

Answer 2

all chemical rxns that occur in the body to maintain itself

Question 3

Exercise Metabolism

Answer 3

Bioenergetics as it relates to physiologic changes during exercise

Question 4

ATP

Answer 4

-energy currency of cell
-splitting supplies energy for muscle contraction
-atp is reformed from ADP with a phosphate from PCr
-macronutrients are fuel sources metabolized to generate ATP

Question 5

Fuel Sources Metabolized to produce ATP

Answer 5

Carbs- 4kcal/g glucose or glycogen
fat-9 kcal/g
protein- 4 kcal/g but role in energy production is limited

Question 6

Stores of glycogen

Answer 6

Liver- 80 g 320kcal
muscle- 460-520 g 1849-2080 kcal
-adipose >100,000 kcal

Question 7

Phosphocreatine

Answer 7

-5s or less high intensity
-restores ATP stores after depletion
-allows for constant replenishment
-does NOT require oxygen

Question 8

Anaerobic Glycolysis

Answer 8

-high intensity 30s -3 min
-glucose is supplied mainly from breakdown of glycogen
-rapid ATP
-lactic acid production

Question 9

Aerobic metabolism

Answer 9

lower intensity, long duration
-aerobic glycolysis and B-oxidation of fats
-oxidation of fats leads to large amounts of ATP
-Three proccesses: Aerobic, krebs, ETC
-Lots of ATP but very slowly
-unlimited system capacity

Question 10

Influence of Duration on source of ATP

Answer 10

1-5s: PCr
5-10s: PCr, anaerobic
>1 min: PCr, anaerobic (dominant) , Aerobic
Several minutes to hours: Aerobic CHO and Fats

Question 11

Prolonged Exercise

Answer 11

-energy comes from aerobic
-Steady state oxygen update can be maintained
-hot/humid envo can effect this
-Oxygen consumption is an indicator of aerobic metabolism

Question 12

Short-term Intense Exercises

Answer 12

-energy from anaerobic pathway
-length of activity determines PCr or glycolysis
-transition from PCr to glycolsis is a gradual shift
-

Question 13

Estimation of Fuel Utilization

Answer 13

Respiratory Exchange Ratio: VCO2/VO2 (carbon dio produced to oxygen consumed)
-fat requires more O2 than carbs
-determined using a metabolic cart during steady state exercise
-at rest RER is 0.75 (85% fat and 15% carbs)
-Intensity increases so does RER
-Misconception: Low RER at low intensity uses more fat

Question 14

Intensity and Fuel Selection

Answer 14

-Fat for low-intensity exercise (30% VO2)
-Carbs for high intensity (70% VO2 max)
-highest rate of lipolysis is 60-65% of VO2

Question 15

Duration and Fuel

Answer 15

at a given intensity as exercise duration increases there is a gradual shift from carbs to fat utilization

Question 16

Fuel Use: CARBS

Answer 16

-major macro for ATP
-glycogenosis is primary regulator of blood glucose
-come from both glycogen in muscle and blood glucose

Question 17

Fuel Use: FATS

Answer 17

-mainly stored as triglycerides in adipocytes which must be broken down into FFAs
-Low intensity: FFA from adipocytes are energy source
-High: increased use of muscle tris
-Increase duration: Plasma FFA

Question 18

Fuel Use: PROTEIN

Answer 18

-very small role in fueling
-must be broken down into AA
-skeletal muscle can metabolize certain AA into ATP
-glucose stored in non -exercising muscle can be delivered to exercising vis glucose alanine pathway