hello welcome to this exam question video today we are going to be looking at epoc or as it's
also known excess post-exercise oxygen consumption and we are looking at it at a gcse level it does
go into a little bit more detail when you get to a level and beyond but for today we are going to be
looking at the the fundamentals of this this term and its its effect on the body uh before after
exercise and in this scenario what we're looking at here is what the subject rosie her breathing
immediately after intensive exercise now that's quite an important point there intensive exercise
because epoc does occur if we were finishing sub maximal or low to moderate intensity exercise but
it would take on a slightly different shape form it would be slightly different quantities and for
durations so this is quite an important point to note down it's intensive exercise because it gives
a clue as to the challenges that the body has been placed under which is mainly anaerobic if we are
completing intensive work then we're obviously going to be in a energy deficit or an oxygen
deficit where we have to respire anaerobically releasing energy from our foods without the
presence of sufficient oxygen so what sort of challenges does that actually put on the body
well first of all the foster creative stores which are responsible for the first 10 seconds
of energy supply they're going to be depleted so we know that we're gonna have to be putting
those back together we also know that there's going to be some development of lactic acid
accumulation in the muscles as well because as we respire anaerobically we know that as the
glucose is broken down we know that lactic acid is given off as a byproduct and there might also be
a build or a slow build up of co2 now we know carbon dioxide is produced as a result of
aerobic exercise but depending on how intense this exercise and how long this exercise was going for
there would have been an element of aerobic exercise as an undercurrent not the main supplier
of energy but there would have been some occurring therefore there would be some co2 being produced
as well so we'll start with the first part of this question which is what actually happens to
rosie's breathing immediately after exercise well breathing can be impacted in two different ways
we've got the breathing rate and the breathing depth so the frequency of our breaths and then
in each one of those breaths how deep do we breathe in how much air do we put into our lungs
how much air do we exhale so if we have just finished intensive exercise we know that rosie
will be maintaining her heightened or increased breathing rate it would have increased from rest
to her peak period of exercise and we would have maintained that level it wouldn't suddenly
drop and then spike again it would maintain from whatever level she finished that intense exercise
at from there it would then start to trail off but epoch it would start off with that main that
maintenance that that maintenance of increased or heightened breathing rate alongside that
there will also be deeper breathing so during that exercise it's likely that rosie would have
experienced you know a little bit more mechanical control over her inspiration and exhalation
increasing her tidal volume or tidal volume being the volume of air that we breathe in or out
per breath so it would have been deep breaths with more being exhaled therefore more being
inhaled each breath again that would have been maintained now what could be interesting to see
on the actual graph would be if her frequency of breathing were to gradually decrease
that would give more time in between each breath now in that time it might be that rosie is able
to take slightly deeper breaths so we might start to see breathing depth or tidal volume increase in
the initial stages of epoc but that's so that's a nuance what you want to be saying is the breathing
rate is maintained at a high level and we breathe deep in our inhalation and that exhalation so we
have an increased tidal volume as well now the reasons why would our breathing stay at this
heightened level but we have to be thinking about putting our body back to its resting
conditions putting us back into homeostasis and it's reverting any changes that occurred because
of this anaerobic intensive exercise well at the start of intensive exercise we know that there is
an oxygen deficit or an oxygen death so why do we continue with this epoch because we are repaying
that oxygen index there wasn't enough at the start therefore we had to complete anaerobic activities
so now that we are reducing our physical demands we've got the opportunity to put extra oxygen back
in to reset our body so repaying oxygen debt or oxygen deficit second we start to break down and
remove the lactic acid now obviously this process could occur for a few minutes or a few hours
even a few days after the exercise depending on how intense that was but the the process can begin
during epoc this excess post-exercise oxygen consumption immediately following the exercise
what we also have is a resupply of oxygen into the muscle so we have hemoglobin in the blood
and we have myoglobin in the muscle and these are responsible for changing oxygen out of the
blood and into the muscle or following intense exercise there's going to be a short supply of
oxygen in the muscle myoglobin isn't going to have much oxygen with it therefore as the blood and the
hemoglobin comes around with this fresh batch of oxygen because of this epoc we're going to start
resupplying the muscle resupplying the myoglobin with oxygen ready for the next bout of exercise
so we've got the slow or the initial breakdown of lactate we've got the replenishment of myoglobin
with oxygen or replenishment of the muscle oxygen stores we've got the repayment of
the oxygen deficit that happened at the start and we've also got the resynthesis of phosphocreatine
that fuel source that we spoke about earlier which supplies the body with with its first 10 seconds
worth of fuel so we use that oxygen to enable aerobic processes which can release the energy
which can re-synthesize those phospho-creative molecules and by doing all of that we can start
to recover the body from the anaerobic work that it just produced and that's that so epoc excess
post exercise oxygen consumption what happens after exercise we maintain an increased breathing
rate and we maintain a deeper or greater tidal volume in comparison to resting levels why do
we do this because we just completed anaerobic activity therefore we need to repay the auction
deficit that was there at the start we replenish the muscles oxygen stores we start to take out the
lactic acid and we can start to regenerate our fossil creatine stores all in time for our next
exercise session so we hope you found that useful and i'll see you again in the next one bye for now