I should admit that even with my modest sports science education, on at least 3 occasions to altitude I have made a horrible misjudgement of my own personal abilities leading to a heaped collapse of breathlessness*. Well at least I can’t be accused of avoiding experience.
Altitude has been a focus for the sports physiology community for many a year, prompted most keenly by the controversial award of the 1968 summer Olympics to Mexico City. The stadium sat at 2240 m above sea level (watch out for those who say that “all events were held at altitude”, yet they strangely forget the sailing, which was held in the Bay of Acapulco – on the sea, which I think it would be uncontroversial to say is as close to sea level as you could get!). For years the complexity of sending athletes to altitude, with high costs, lack of optimal facilities, difficulties with controlling control groups confounded studies and their conclusions. The scientific community would generally be happy with the conclusion: Altitude training improves your ability to perform at altitude. What they are equally right to, in the face of quite a varied evidence base, declare non-commitally – that it is not clear whether, or altitude exposure might improve sea-level performance.
Time for some definitions, but these will be largely irrelevant to the message of the article and are defined properly elsewhere;
- Altitude – ascending to a land height of >1600m, probably not higher than 2500m for a sojourn (essential altitude vocabulary – must be delivered with flamboyant hand gestures and puckering of lips) of 2-4 weeks – long enough to get a response (3 weeks) but not so long that camp fever sets in (6 weeks). This is often labelled as live high train high (LHTH) but could also be live high train low (LHTL) if suitable facilities are available for a quick journey down the hill for a quality session.
- Hypoxia – use of artificial environments to simulate altitude by manipulating the percentage of oxygen in the air rather than the atmospheric pressure. Chambers, tents and mask systems are used to contain or direct hypoxic air to the athlete normally when they are at sea-level. This could be LHTL or intermittent hypoxic training (IHT) or indeed live even higher whilst your already training at altitude too.
For the purposes of the blog altitude and hypoxia are the exposures that act as the stimulus.
Of the 10 or so altitude training camps that I have supported, all of them bar-none has included a frequent dinner table-conversation of whether this altitude training works or not. The table would often be split into, ‘I really benefit’, ‘I really struggle’ and ‘I am not sure’. This is known as responders and non-responders. In this instance, when the training is hard the physiologist’s primary role is to help the athlete survive. When the training gets tough (high breathing and heart rate, higher blood lactate response to given intensity), good measures of the specific responses will help the athlete and coach understand where they are stuggling and if they are struggling too much. If the athlete starts to tire, struggle to cope, get ratty, have disturbed sleep, lose their appetite, then the first port of call is the magic recipe of quality rest, nutrition and hydration as the basic reference point for recovery and fatigue managment. This is not to shirk the important conversations about adjusting subsequent training sessions though, but this is better performed with a few days of observations and clear evidence of breakdown, etither physiological or performance. The last thing a coach or athlete needs is a physiologist all to ready to call an ambulance in the face of a lactate 2 mM higher than normal.
With the predominant positive adaptation to altitude/hypoxia being blood based, specifically erythropoietin mediated red blood corpuscle neoformation, the bottom line in the process is the mass of haemoglobin in the body (relative or absolute).
Optimised by the German based group of Walter Schmidt and Nicole Prommer and tweaked by Chris Gore, David Martin and Laura Garvican at the AIS, the measurement of Hb mass through a carbon monoxide (CO) rebreathing technique has enabled altitude goers to have their ‘response’ quantified. Using this technique over the last Olympic cycle our UK physiologists (known on the ‘streets’ as the Haemoglobin Massive – Jamie Pringle, Barry Fudge, Gareth Turner, Ben Holliss, Charlie Pedlar) have been able to demystify who responds and who doesn’t and sure enough with initial exposures a similar spread of responses is observed. We could just leave it like that and condemn those that don’t respond to staying native to sea-level for their careers. Or we could ask why they don’t respond and work our way through the problem. Could it be the level of oxygen desaturation experienced for a given altitude/hypoxic exposure? Could it be the underlying iron status of the athlete determining the raw materials for haem group synthesis? Could it be the inflammation status of the athlete, perhaps in proportion to training/recovery balance, that governs the pathway of EPO synthesis? I don’t think anyone is certain at this moment in time.
What does seem to be clear is that if you can resolve these variables, in combination with the manipulation of pre- and post- exposures and ‘heights’ of altitude stimulus – you can provoke a positive response in nearly all. Indeed the levels of Hb mass changes observed through appropriate individualisation of the stimulus can outstrip those commonly reported in the literature. So it is less of a case of responders vs non-responders, it is more a case of individualised protocol or non-individualised protocol (although that isn’t catchy). I am not sure that this could be easily or meaningfully written up in the literature – the methods section would ostensibly be individual case protocols full of tinkering and unusual approaches to initiate similar responses. Effectively though altitude/hypoxia for sea level performance can now be summed up in two words – “it works”.
I will leave you with some future thoughts. Up until now, in this particular blog, I have not referred to the event categories that altitude/hypoxia can positively effect. Your assumption, I presume, is of course the aerobic events, from middle distance upward, where oxidative processes dominate energy turnover, and you would be correct that that is where most of our work has been. Commonly we don’t think of the 400m run or 100m swim or the sprint cycle as target sports for benefitting from altitude/hypoxic. However, the energy contribution to such events is still 20-45% from oxidative processes – so it seems perverse that one wouldn’t spend time and effort developing such a capability perhaps using altitude/hypoxia. Jim Hines the 1968 100m Olympic gold medallists commented that the 100m dash in Mexico was the hardest he had ever done (which reminds me of sprint reps when at altitude feeling like double the effort). The point being that lack of oxygen in the system intensifies the potency of the existing stimulus, be it during exercise or at rest. Just as recently, the response to strength work has been shown to be increased in hypoxia – the lack of oxygen just makes it harder. It would be interesting if future studies could more comprehensively explore the effect of altitude/hypoxia on high power training and performance. So I wonder whether in the future we might be able to work on going to Altius to go Citius and Fortius.
Altitude and hypoxia, at least in the UK, have been waiting to be applied fully. The number of unknowns has become fewer, primarily due to the use of the CO rebreathing technique and its application to the individualisation of altitude/hypoxia has meant a far greater number of athletes can benefit. This has led to sports changing their approach and attitude to altitude/hypoxia. Why? Because for the first real time in our system, altitude/hypoxia can be applied with the assurance of knowing and/or ensuring a cost effective return on investment. So for its performance benefit, individualisation potential, but most significantly that an application of sports physiology can move mountains (see what I did there) and convince sports to mould whole training strategy – CO rebreathing for the measurement of Hb mass takes the no. 2, the silver medal slot, in my top 10 applications of sports physiology.
*1999 – Race to the mountain cross at Silvretta whilst away with the rowing team – after 5 minutes I had lowered my sprint to a walk but still could not get my heart rate down. Height 2050m
2000 – Sprint swim at the start of water polo game at cross training camp at Sierra Nevada also with the rowers. I am pleased to announce that I won the ball, threw it back, flapped to the side and was no use for the rest of the game. Height 2320m
2001 – On a rest day with Bobsleighers in Park City, I skied down a wrong turn off-piste by about 100m, I clambered back up in deep snow, collapsed to the floor in a frenzy of wheezy panting only to be inspected by some ‘dudes’, (to be read in gnarly American accent), “Hey man, are you ok?”. I rolled over, skis akimbo, only to reveal the GB Olympic kit symbols on my coat (mistake), which was met with, “Oh my god, it’s the British ski team!” I couldn’t resist replying between gasps, “I’ll…be…ready…in…time…for…the…Games” (4 months before Salt Lake). Height 2950m
None to report since.
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