Friday, 16 December 2011

Anti-oxidant supplementation in endurance training- Is it necessary?

Free Radicals are produced through everyday activities and are thought to cause cell damage and in the defence against these threats are anti-oxidants. Therefore interest has surrounded the importance of dietary anti-oxidants and many health conscious people and athletes have turned to nutritional supplements to ensure that these are covered within the athlete’s diet, leading to antioxidants being the likely most common sports supplement used by athletes.

However, recently there is more evidence that the presence of free radicals has important physiological functions in cells and the balance between these and the anti-oxidants are an important for any physiological functions.

Anti-Oxidants

There are two types of anti-oxidants endogenous and exogenous- in both cases they scavenge the Free Radicals and convert them to un-reactive species and therefore minimising the damaging effects.

Those not synthesised by the body need to be obtained extrogenously and include vitamin A, C (may strengthen immune defence) and E (enhance energy balance at high altitude).

In some cases counteracting reactive oxygen species (ROS) via acute antioxidant supplementation can positively affect performance and maybe protect against ROS induced fatigue.

However more recent findings do not support the belief that ordinary anti-oxidant substances such as Vitamin A, C and E improve performance or delay fatigue in those athletes who have a well balance and varied diet (Rodriguez 2009). Similarly, supplementary vitamin C an E does not have a protective effect against muscle damage (Beaton et al 2002).

There is also the case that these ROS play an important signalling role for adaptation of endogenous oxidant defence system and for mitochondrial genesis and angiogenesis and when radical appearance is overly suppressed these signals may therefore be weakened or abolished, therefore questions have been raised about efficacy of high doses of exogenous anti-oxidants such as Vitamin C and E during endurance training and that they could be counterproductive.

Conclusion

This perhaps opens the debate around the use of anti-oxidant supplementation. Its too early to condemn all forms of anti-oxidant supplementation it is also recognised that there are certainly circumstances in which supplementation is probably advantageous such as high-altitude training camps, since free radical production is intensified and endogenous defence weakened in hypoxia, or around important competitions where only the eventual benefits remain relevant.
It is necessary that the right balance is needed for optimal health and training effects and this optimal balance remains open, alongside the effects of dose and timing.

For now the case may be for athlete’s to realise that sometimes in terms of anti-oxidant supplementation it is not the case of the more the better, and the key is to have a healthy balanced diet, which contains a wide range of fruits and vegetables to maximise anti-oxidant intake through natural sources.

Antioxidant supplementation and endurance training: Win or Loss?
Gross et al (2011) European Journal of Sports Science; 11 (1): 27-32

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