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Asked by limey5298 to Helen, Jenni, Mark, Martin, Stu on 17 Jun 2011.
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Helen O'Connor answered on 13 Jun 2011:
I should know the answer to this as I had to study what is called the “oxygen debt” or “excess post-exercise oxygen consumption” (EPOC) when I trained as an aerobics instructor but I am afraid I could not start to explain the process now. I am sure the other scientists in the zone can do an excellent job of explaining this though.
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Mark Burnley answered on 13 Jun 2011:
You get out of breath because running 400 m is a long sprint. You’ll probably complete the distance in 60-90 seconds and so you will be running at such a speed that your heart will not be able to supply enough oxygen to fuel the muscles’ needs (as Helen mentioned). However, what makes you out of breath is not a lack of oxygen but rather the large amount of carbon dioxide you produce in this effort. Because you are running so fast, your body produces a lot of lactate. Along with this lactate comes a hydrogen ion (H+), and you can’t have too many of these in the body because they will make the body fluids acidic. So the body “buffers” the H+ using biocarbonate (HCO3-) which produces CO2 and H2O. This raises the CO2 concentration of your blood, which is detected by receptors in the aorta and carotid arteries, and the respiratory centre of the brain, which then causes you to breath more deeply and more frequently. This will continue until the CO2 levels in the blood are back to normal, which takes about 4-5 min. This is why you keep breathing hard even after you’ve stopped (or if you sprint 50 metres you may not breath at all, but in the few minutes after you’ll notice that you’re having to breath harder). So it’s all about CO2 (well, almost all about CO2 anyway).
To finish off, next time you watch a TV show where there has been a chase on foot, notice how quickly the actor’s breathing returns to normal – within a few breaths, which is not possible (they do several takes of the dialogue, so there is no urge to breath harder) – and compare it to the interviews athletes do after a race, where even the sprinters are struggling to speak, which is real!
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Jenni Tilley answered on 17 Jun 2011:
You’re doing better than me… I get out of breath when I run 100m!
Comments
nunu commented on :
Cause your unfit.
Jenni commented on :
well actually, I cycle up hills all the time and do lots fo step classes. I’m just not accustomed to running. But thanks for that!
Helen commented on :
8)
hille commented on :
how do you get out of breath when you do 1500m
olzz commented on :
you see 400m is intense its a mixture of anaerobic and aerobic systems, and it depends how well you run it aswell. for example if you go full out at the start you use your fast glycolytic fibres which only last for 10 seconds or so, and after that you use you fast oxidative, which you need oxygen for. ok so if you want to prevent heavy breathing, you have to pace yourself for example do a few 400m and find out, where your feeling most of out breath, then retry and slow it down, and stride it out, then obviosly when you get to the 60-50m mark you will increase the speed. just think of it as a fast jog where you have to try maintain your speed do not set off like a 100m sprint because you will jsut tire yourself out 😛