The Tour is over, the visitors have left and it has been back to training for the last few weeks. I am currently in week 6 of my new annual training plan that I have designed using Joe Friels training Bible. I did the suggested lactate threshold test about 2 weeks ago and was suprised that my threshold was about 10 bpm more then I had assumed. The hours are long but because of the drop in intensity I am feeling quite good with no back pain because I have been stretching my hamstrings and glutes often. Summer is finaly starting to come back and I can't wait, I hate the cold and this is another reason why I am so grateful to live in Brisbane. I was doing some research on training in the heat for the upcoming summer and came accross this interesting article.
The first thing (and this is a dramatically summarized version) is that the winner has to be small in size. All things being equal (which we concede they never are!), the smaller athlete will win a race in the heat. Many studies have shown this, and the equations that we use to model performances in the heat suggest the same. Basically, it boils down to a balance between height production and heat loss. Heat production is dependent on body size and running speed, while heat loss is a function of body surface area, and the environment. Obviously, the environment is the same for everyone, but body size is not. The smaller the athlete, the less heat they produce, but their heat loss is not reduced by as much and the end result is that the smaller athlete will store less heat running at a certain speed than the bigger athlete. Ultimately, this means that a smaller athlete can afford to run slightly faster before their body temperature rises. Big advantage! This is of course a oversimplification, but it does illustrate the point that when the mercury starts climbing, the advantage lies with a smaller runner.
Doing time in the heat - acclimatization is vital
The next important factor is acclimatization. Numerous studies have shown just how much performance improves after a period of adaptation to the heat. The guru of exercise in the heat, Bodil Nielsen of Denmark, has done many of these studies, and has shown how exercise tolerance improves almost two-fold after a period of hot weather adaptation. That is, athletes can go twice as far in the heat on the 7th day compared to their first day in the heat. This means that a winning athlete is one who is well adapted to running in the heat. The advantage here lies with the locals (Japanese and Chinese, and perhaps the Africans), though all the major contenders will almost certainly have spent a period of acclimatization before this race. The exact physiology behind the process is quite complex, but it involves increases in plasma volume, which enables more heat loss, increased recruitment of sweat glands, and in a race situation, the perception/sensation of heat is without doubt key as well.
The role of the brain in all this
Then finally, exercise is ultimately regulated by the brain. Whether one makes an athlete exercise in the heat until they are exhausted, or whether it is a race/self-paced situation, exercise in the heat is ultimately limited or regulated by the brain. So for example, if one runs at the SAME SPEED until exhaustion in the heat, the final body temperature is around 40 degrees. It is as if there is an 'off-switch', a point where the brain simply says enough is enough, and stops activating the muscle. And the afore-mentioned Nielsen, with Lars Nybo, have found this in studies. Once the body temperature hits this limit, the activation of muscle by the brain is reduced.
Have Fun Don't Fall
