Liuy's PE Questions

[Liuy]

Can the build of inorganic phosphate molecules and hydrogen ions be attributed to an athlete reaching LIP?

what happens at LIP for this build up to occur?

[lexitu]

There is no build up at LIP, beyond LIP there is accumulation of H+ but there is no direct correlation with Pi.

[Liuy]

When does Pi accumulation occur then ? :S

I think I read in PE notes or something that beyond LIP something happens in relation to an increase in metabolic by-products, thus causing fatigue.
Can't remember what specifically though

[lexitu]

I'm not sure about Pi accumulation as far as the specifics (and you definitely don't need to know) - but simply it'll be in higher concentrations when ATP is being resynthesised (and hence broken down at a faster rate). Because the ATP-PC system releases ATP at the fastest rate, then inorganic phosphate concentration will increase. Also note that in the ATP-PC system there is Pi from PC splitting and Pi from ATP splitting.
Essentially Pi concentration increases with intensity. With intensities in excess of LIP there is an increase in fatiguing by-products from anaerobic metabolism - but that's pretty obvious because intensity is increasing and there is no longer a steady state.

[lexitu]

what happens at LIP for this build up to occur?

Realised I forgot to answer this Beyond LIP there is a build up because H+ removal no longer equals the rate of H+ entry into the blood - that's the simple explanation which doesn't really explain anything. The actual reason for the build up is contentious and heavily researched, but they think it might be something to do with disrupted oxidative processes and reduced blood flow to sites of lactate and H+ removal, rather than insufficient oxygen supply itself.

[Liuy]

Thanks mate

[Liuy]

Why does Diastolic pressure stay relatively unchanged/even decrease slightly during exercise?

[lexitu]

Haha, something I was asking at uni for a better answer, didn't really get it First of all, you definitely don't need to know this, but here's my go at explaining it:
- Systolic blood pressure is going to increase drastically because the heart contracts more forcefully hence blood exerts more pressure on arterial walls
- Diastolic blood pressure is when the heart is relaxed and the arteries are helping push blood along. Some arteries can expand a bit which helps accommodate for the increased blood flow during exercise. If there's more blood in a really tight space then pressure goes up, but because vasodilation occurs slightly, then this doesn't change majorly.

Does that kind of make sense?

[Liuy]

Wow, that is some complicated stuff Lex !
Makes sense though

Thanks heaps man, there doesn't seem to be a question which you can't answer.

[lexitu]

Haha, no worries mate

[Liuy]

Does Lactate accumulate during steady state?

(would this be beyond the scope of the course?)

[lexitu]

Nope it doesn't. LIP is the last steady state intensity - beyond that lactate accumulates Obviously, lactate is still being produced at a steady state, though.

Definitely within the scope of the course and examinable

[flash36]

LIP will be on the exam. Each year since it's introduction into the course, questions about it have been handled poorly. So make sure you've got it covered.

[Liuy]

Checking my answer for "why does an increased A-VO2 difference occur during exercise?"

"A-VO2 difference increases during exercise because there is an increased demand for available oxygen on the part of the muscle to facilitate the chemical reactions which are part of ATP resynthesis. Working muscles will therefore extract more of the available oxygen in the passing arterial blood (as much as 75% of available O2). resulting in a decreased oxygen concentration in the venous blood."

[flash36]

Perfect.