Here is an article that i wrote for Fighting Fit magazine..... (http://www.fightingfitmagazine.com/)
It seems the ‘fitness’ industry aren’t satisfied with polluting the profession of strength and conditioning with kettlebells, bosu’s and all the other kinds of circus equipment , gas masks are now the latest commercial scam that seems to be everywhere at the minute.
Lets break down the supposed reasons for using such a piece of apparatus for the training of athletes.
The main phrase banded around on this subject without due thought is ‘hypoxia’. Levine, B High Alt Med Biol 2002 describes hypoxic training as ‘ the discontinuous use of hypobaric hypoxia, in an attempt to reproduce some of the key features of altitude acclimatisation, with the ultimate goal of improving sea level athletic performance.’ However too fully look into this type of training it is necessary to understand that there are two implications for hypoxia training, hypoxia at rest and hypoxia during training.
Gas mask training is clearly aimed at the later form of hypoxia training. This however, maybe where the confusion with regard to the benefit on performance has arisen. There is plenty of research (Mazzeo 1991, Wolfel 1993 ) to demonstrate that subjectively, similar training stimuli are perceived to be harder and heart rates, ventilation rates and lactate levels are found to be higher, when performed under hypoxic conditions. However there is also large volumes of evidence to suggest that there is little or no demonstration of improvement to functional measures of performance:
Both, Vogt et al in 2001, Terrados et al in 1988 and Vallier et al in 1996 found no difference in VO2 max or maximal power outputs.
Loeppky and Bynum 1970, Roskamm et al both found no effect on VO2 max and more importantly on heamaglobin / hematocit levels.
Sutton et al 1988, 1992, Cymerman 1989, Hochachka 1989 and Reeves et al in 1999 all demonstrated that ‘neither the cardiovascular system nor the metabolic state of skeletal muscle are ‘stressed’ to a greater degree’ during intermittent hypoxia training.
Even when idea of making an athlete train ‘harder’ to make them feel like they have pushed their mental and physical boundaries is considered, more research has been done to dispel that idea. Levine et al in 1992, Levine and Stray-Gundersen 1997 and Bronson et al in 2000 all quote that, ‘Although hypoxic exercise may feel harder, athletes of many different types self select work rates that are significantly less during hypoxic exercise compared to under normal conditions’. This is not really to suggest that athletes are consciously opting to train at a low intensity but the conditions do not allow them to replicate the same training outputs that they would at normal altitude.
Even if there was some physiological benefit, it is well know that to adapt to a training stimulus there must be an initial decrease in performance before the supercompenstatory effect. However training with a gas mask for very small amount in the day (1 hour in 24) will not provide enough of a stimulus to evoke a change in an athletes basic physiological homeostasis. For this to happen the stimulus must be longitudinal and consistent.
The other type of hypoxia training, is hypoxia at rest. Levine refers to this in his review and states ‘Continuous exposure to hypobaric hypoxia at rest, either as real or simulated high altitude, stimulates the process of acclimatisation which includes a number of physiological adaptations that improve the ability to work at altitude but may well be advantageous for exercise performance at sea level.’
Because an athlete and their physiology is being consistently exposed to conditions that are outside of their regular threshold, there is a basic need for adaptation. This usually comes in the form of increased haemoglobin and hematocrit. Ekblom et al, Buick et al, Williams et al, Berglund and Brikeland et al have all researched and demonstrated increases in this physiology and its associated improvements in oxygen carrying capacity and aerobic power. As well as this, the negative effects on the down regulation of skeletal muscle structure and function associated with training under acute hypoxia, are avoided.
In practical terms, the ‘live high, train low’ model popularised by Levine and Stray-Gundersen is the most efficient way to get the benefits of the physiological adaptations that occur at altitude. From personal experience, a live high, train high and compete low’ protocol for a period of 16-21 days at altitude is an excellent way to prepare for competition at sea level. The time scale allows for the initial decrease in training output, the acclimatisation phase and finally the physiological adaptation before dropping back down to sea level 3 or 4 days before competition.
(not included in the article)
Many of the beneficial adaptations to altitude training are because of the decreased partial pressure of oxygen in the air. One of the key adaptations of altitude is that the decrease ppO2 stimulates in increase in 2,3 diphosphateglycerate which in turn allows for an increase in oxygen dissociation and a rightward shift inthe oxyheamaglobin dissociation curve. This increase in 2,3DPG actively promotes oxygen unloading at the muscle and therefore increased oxygen utilisation. HOWEVER, this is NOT what happens ina gas mask. The partial pressure of the air in the gas remains the same and only the VOLUME of air is changed. Total air volume is not a limiting factor for performance, the content of the air available is the key issue.
