Hypoxic training and Performance I

Hypoxia is generally defined as the condition that occurs when the human body is exposed to a hypobaric environment, where the decrease in atmospheric pressure entails a reduction in oxygen partial pressure from its sea level value. Although the gaseous components of air and their percentages are exactly the same than at sea level (78.09% nitrogen, 20.95% oxygen, 0.039% carbon dioxide, 0.93% argon and 1% water vapour), at high altitudes, the same volume of air contains a lower amount of gaseous molecules, a fact which translates in a decreased partial pressure of the gases and therefore in a variation in the oxygen diffusion gradient.

After the 1968 Summer Olympic, held in Mexico City at an altitude of 2.240 m on sea level, the effects of hypoxia on human performance drew the interest of many exercise physiologists. Indeed, as it is well known that the ability of the cardio-respiratory system to deliver oxygen to the exercising muscles is one of the limiting factors of performance, particularly in endurance sports, investigating the physiological responses of endurance athletes to a short or long term exposure to hypoxia was considered essential to elucidate the effects of such exposure on sea level and altitude performance. Particularly, it was considered the possibility to use hypoxia as a training stimulus to enhance endurance performance.

To date, the scientific literature reports findings which are still equivocal about the efficacy of hypoxia as a training method, especially when it was used to improve sea level performance. Possibly, the reasons of some of the incongruences currently reported might relate to the difficulties in controlling the wide range of variables involved when investigating the effects of such environmental stressor on performance. Indeed, the degree of hypoxia, the duration of the exposure to hypoxic conditions, the exercise intensity (absolute vs. relative workloads), the inter-individual variability in adapting to hypoxic environments (‘responders’ vs. ‘non-responders’) are all parameters that can significantly vary the outcomes of any investigation.

However, despite the difficulties in drawing any conclusion about the real potential of hypoxia as training stimulus for endurance performance, many endurance sport teams frequently introduce an exposure to altitude in their annual training plan, even when a clear understanding of the mechanisms behind this training stimulus is sometimes limited or missing.

Davide Filingeri

MPhil Researcher

Environmental Ergonomics Research Centre

Loughborough University 

References

Bassett DR Jr, Howley ET (2000) Limiting factors for maximum oxygen uptake and determinants of endurance performance. Med Sci Sports Exerc 32: 70-84

Bonetti DL, Hopkins WG (2009) Sea-level exercise performance following adaptation to hypoxia: a meta-analysis. Sports Med 39: 107-127

Filingeri D, Mancuso EP, Paoli A, Bianco A, Palma A (2011) Is hypoxia a training stimulus for endurance athletes’ performance? A brief review. Italian Journal of Sport Sciences and Law 4 (4), 153-162

Rusko HK, Tikkanen HO, Peltonen JE (2004) Altitude and endurance training. J Sports Sci 22: 928-944