L33 - Metabolism 3 Flashcards
How is RER calculated?
RER = VCO2 expired / VO2 inspired
What are characteristics of ATP in the body?
finite amount, low levels in the body: 80-100g
immediate energy source, all muscle ATP consumed in ~90 sec at rest and ~2 sec during exercise if not regenerated, ATP levels in muscle are maintained quite well, must be continuously resynthesised and replenished
What are the mechanisms involved in the breakdown and resynthesis of ATP?
- substrate level metabolism (anaerobic); phosphagen system and glycolysis
- oxidative metabolism (aerobic); carbohydrate, fat and protein
Does energy come from aerobic or anaerobic sources during a sprint?
anaerobic sources
aerobic sources during long-distance running
Which systems have the highest rate of ATP generation?
PCr and glycolysis
Which systems have the highest amount of available energy?
CHO ox and fat ox
Do system operate in isolation?
no, all pathways contribute but contribution depends on factors such as exercise duration and intensity
What happens during aerobic metabolism?
increased oxygen uptake, increased blood flow and oxygen extraction at the tissue
How does the phosphocreatine system work?
PCr + ADP -> ATP + creatine (creatine kinase)
relatively modest store, immediate use during exercise (0-1.3s), rapidly depleted
What are the characteristics of glycolysis?
energy acquired from large muscle glycogen stores (500 mmol/kg dm) occurs rapidly (≤ 2 sec)
How does carbohydrate exist in the body?
stored as glycogen in muscle and liver
circulates in blood/plasma as glucose
How do fatty acids exist in the body?
FFA released from adipose tissue triacylglycerol stores
intramuscular triacylglycerol
How does protein exist in the body?
amino acids (long duration exercise, not addressed herein)
When does muscle glycogen participate in energy production?
only at 65% and 85% of VO2 max
What are factors that affect fuel selection?
substrate availability, diet or nutritional status, prior exercise, muscle fibre type composition, physical fitness or training status, environmental factors, gender (male/female)
