lecture 16 - Aerobic exercise, effects of intensity and duration on metabolism Flashcards
(25 cards)
what is VO2 max?
Optimal maximal oxygen uptake
as the length of exercise increases what happens to oxidation?
it is still important but is no longer the only production process
what is high intensity exercise?
- Energy derived from anaerobic sources; PCr at very rapid intensities and anaerobic glycolysis
-Less energy is derived from intramuscular stores (e.g., glycogen and lipids) - Type II and type IIx ‘fast twitch’ muscle fibres play a more important role
what is aerobic exercise?
- Energy derived from lipids, carbohydrates (and some protein)
- Type I ‘slow twitch’ muscle fibres play a more important role
- Energy use dependent on intensity
at lower intensities where is energy mostly derived from?
lipid sources
at higher intensities where is there a greater contribution from?
carbohydrate sources
where does fat utilisation peak at relating to vo2 max?
65% and then declines after
can the amount of fat that can be oxidised be increased with training? (Bagley’s study)
yes
bagley (2012) - 12 weeks of sprint interval training – after 12 weeks amount of fat they could produce was sig
Why is the body not able to continue to use fat as a fuel source at high intensity exercise?
- Reduced blood flow to adipose tissue (As a consequence, free fatty acid delivery to the exercising muscles is inhibited, limiting the oxidation rates)
what happens to the rate of glycolysis at higher exercise intensities?
it increases, more pyruvate made, more turned into Acetyl CoA - too much produced which can’t enter the krep cycle
how do we prevent this excess acetyl coa?
binds to acyl carnitine where it is then neutralised into this
- Now this carnitine cant be used for binding acetyl coa – so means less FA can be used in energy production
what is one of the main reasons as to why we can’t oxidise fat at higher exercise intensities?
the amount of carnitine
as the rate of exercise increases what happens to the rate of ATP turnover?
it increases - Stimulates the metabolic pathway – primarily activated by glycogen phosphorylase
without PDH what can’t be oxidised?
acetyl CoA
if we keep exercising at a fixed intensity the contribution shifts so what do we rely on mostly?
fats
as exercise duration increases what happens to our glycogen stores?
they deplete as there is a higher reliance on lipolysis
what are the mechanisms of fatigue?
Pcr stores are depleted - with endurance exercise whilst our glycogen stores are being depleted we just need to drop our intensities in order to keep going
what are the key non-steroid hormones involved in exercise?
adrenaline, noradrenaline, insulin, glucagon etc
what increases during aerobic exercise?
glucagon, growth hormone, glycolysis, lipolysis and glycogenolysis
what decreases during aerobic exercise?
insulin
what are the key steroid hormones involved in exercise?
cortisol, testosterone, oestrogen and progesterone
what steroid hormones increase during aerobic exercise?
cortisol, oestrogen and progesterone
what steroid hormones decrease during aerobic exercise?
testosterone
what is testosterone, growth hormone and insulin (after eating) involved with?
protein synthesis
