Firstly, apologies for the absence of the bulletins over the last few weeks, we were burgled and I had my laptop stolen! We are back to normal now, so here is the next installment!

Why is it so Tough in the Heat?

The human body maintains a core temperature of 37C and has narrow limits for the happy and healthy working of the body. Heat is a by-product of the various chemical processes inside the body and the process that is particularly relevant to exercise is the conversion of food and stored fuel into energy. It follows that the greater the need for energy, the more heat will be generated inside the body – i.e. the harder you work, the hotter you will get.

When the ambient temperature is high, heat is actually gained from the air and it is harder for the body to cool itself. Sweating is the process by which the body naturally cools down and maintains core temperature. Sweating, although necessary when we are hot, also leads to dehydration and the loss of valuable salts from the body which can impair endurance when exercise and make it generally feel more stressful.

It is estimated that to be dehydrated by as little as 2% will result in a performance loss and dehydration of more than 5% will result in a performance loss of up to 30%.

Combined with sweating the body will also try and send blood to the surface of the skin to help in heat loss, which is what causes the redness when exercising intensely. However, there will be a conflict of blood use inside the body as it is also needed by the muscles and vital organs; this will compromise the blood flow to the skin also causing temperature to rise.

Conclusions – It doesn’t make happy reading for the body when exercising in excessive heat (more than 20C). Be aware that you will lose water more rapidly when it is hotter so keep hydrated before, during and after exercise. Heat is also likely to make the same level of exercise intensity harder to maintain, so be aware of the limitations of a warm environment (especially gyms).

Evidence suggests that working out in heat it not a more effective exercise; it just feels like it is! The body will however acclimatise, which is why some sporting nations are likely to cope with warm conditions better than others.

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