POC...The acronym itself sends shivers down Secondary School students, which is far enough, it did with me back when I was in GCSE PE! So lets have a think about this.
Excess Post-Exercise Oxygen Consumption...or.. in other words, Oxygen Debt. It is the required amount of O2 necessary to achieve normal metabolic function within the muscles, or (for extra points) Homeostasis.
In AQA GCSE PE this would come under the human body and movement in physical activity and sport, to which you would need to understand the definition of EPOC and the causes. Under this blanket banner, you will have to look at Aerobic Respiration (with oxygen) and Anaerobic Respiration (without oxygen).
For revision, remember: Aerobic Respiration = glucose + oxygen → energy + carbon dioxide + water
Anaerobic Respiration = glucose → energy + lactic acid
Anaerobic Respiration (AnR) is the use of stored glucose without creating energy through ATP in the Krebbs Cycle which requires oxygen. You can imagine that the duration for AnR the time is short and not prolonged due to the muscles need for O2 to function normally, think closer to 0 - 30 seconds. Therefore, when you are discussing types of exercise or examples of sports, think Short, Sharp, Explosive. Question : What type of respiration would a 100m sprinter use for their event? (I) What is the duration of Anaerobic respiration and why? (II)
So, EPOC is the direct result of muscles respiring anaerobically, without oxygen, during moderate to vigourous exercise and producing lactic acid within the muscles.
Situation: You are training in Athletics and complete a 5 x 100m interval at Pure Speed (BTEC skill related component of Fitness) / Max Speed. You complete the intervals, finish breathing heavily after and take a number of breaths quickly. It takes time to recover. What is happening to your body? (IV) N.B. In this scenario, EPOC is also a short term effect of exercise on the body, breathing heavily to recover.
Is it only in these short, sharp training sessions that this happens? Of course not, if you were to go for a run, say continuous training, your breathing rate would increase to keep up with the need for oxygen with your muscles. This is when you get Vascular Shunts occur which diverts blood away from your non essentials (organs, digestive tract etc) to your working muscles (VCert). But, if you were to then push your limits at the end, or middle, of your run and overextend your aerobic capacity you would put yourself in Oxygen Debt.
Further, and this brings to an end the more educational side of things, if you were to wear an elevation mask depending on the level you used you would again be putting yourself in EPOC due to lack of O2 to muscles.
How would the graph look if it were HIIT (High intensity Interval training) and not steady state? (5 marks)
Elevation Masks... Do they work? What are they and why I use them.
First off, no, majority of commercial elevation masks will not decrease the O2 within the air as if you are at an altitude. This will mean that you are not training specifically at an altitude equivalent to Mont Blanc, Denali and Ama Dablam. If they do state this, its practically an outright lie. They do not simulate Altitude Training and you will not get the same effects as Altitude training i.e. increase in haemoglobin capacity levels, increase in haemoglobin, increase capillary density etc. The lower atmospheric pressure which reduces the O2 in the air, makes the air thinner, would, eventually, cause performance advantages. But these masks will not simulate it.
Effectively, elevation masks are a tool to simulate "Inspiratory Muscle Training."
This was investigated by a number of researchers in Porcari et al (2016) who formalised the notion that the elevation training mask was, significantly, a tool to train as a inspiratory muscle training device which increased the muscular strength of inspiratory muscles and the performers ability to recover from exertion through increased tidal volume. This was seen in the significant increase in Velocity threshold, Power output and respiratory compensation threshold.
Further research by Ott, Joyce and Hilman (2019) purport that the elevation masks do increase the human growth hormone compared to a control, however does not give significant changes in acute pulmonary function, metabolism or heart rate which lends itself to the notion, and statement that elevation masks are not altitude masks.
Interestingly, Jagim et al (2018) looked at acute factors of wearing an ETM (similar to how in GCSE / BTEC and VCert we look at short term effects of exercise). They wanted to test to see how the use of an ETM effects resistance exercise performance, metabolic stress markers, and ratings of mental fatigue. Although they found that there was no significant difference in exercise performance, there was a negative relationship between wearing the ETM and task focused after exercises such as squats, bench press and sprints. If we were to relate this to EPOC, does it stand to reason that the results after these could be in relation to how performers are at an increased intensity and potentially in the weight lifting scenarios would have utilised the Valsalva technique to increase explosiveness, often causing dizziness as well?
Three studies, three different results which in essence if we were to continue to look at studies and news articles we would find increasing contradictory findings and opinions. Using an elevation mask which decreases the rate of O2 consumption through a filtration system is another tool to enhance performance and puts the body, and mind, in an uncomfortable position where it has to adapt in order to improve. Or at least feel more comfortable.
I use these masks, and have done since 2011, whilst running, knowing that my breathing ability is greatly improved both when wearing and when not wearing the masks. At the moment, I run a certain amount (say 5km) with the mask on, before taking it off and running back. A drop down in restriction which means I can push myself faster, not disimilar to pyramid training and drop down training in gyms. I enjoy wearing them as an extra challenge when running, the literature is contradictory in the advantages of elevation masks, however, from personal use and research, the advantages outweigh the disadvantages.
What would be interesting, is to see how Nimsdai Purja is effected compared to a non high altitude mountaineer when wearing one... Dont think it would affect him too much!
References:
Jagim, A; Dominy, T; Camic, C; Wright, G; Doberstein, S; Jones, M; Oliver, J (2018). Acute Effects of the Elevation Training Mask on Strength Performance in Recreational Weight lifters, Journal of Strength and Conditioning Research: Volume 32 - Issue 2 - p 482-489.
Ott, T; Joyce, M; Hillman, A (2019). Effects of Acute High-Intensity Exercise With the Elevation Training Mask or Hypoxicator on Pulmonary Function, Metabolism, and Hormones, Journal of Strength and Conditioning Research
Porcari, J. P., Probst, L., Forrester, K., Doberstein, S., Foster, C., Cress, M. L., & Schmidt, K. (2016). Effect of Wearing the Elevation Training Mask on Aerobic Capacity, Lung Function, and Hematological Variables. Journal of sports science & medicine, 15(2), 379–386.