After all that winter training, dark evenings in the cold and wet, it is great to be enjoying these balmy summer days, warm, pleasant runs under clear blue skies. And it’s great that we don’t have to endure the hammer-like heat of the tropics.
Except of course we do - sometimes. Temperatures in the upper twenties and thirties are becoming ever more common and we may find ourselves joining the Parisians and getting temperatures in the forties.
These temperatures present our bodies with a problem! Normal body temperature is between 36 and 37 and varies from person to person and from hour to hour. If it rises too much, above 40.5, we are in danger. Fortunately, we have sophisticated body systems to keep it within the acceptable limits.
We are all familiar with the basics of the system for keeping us cool. We exercise, get hot, start to sweat, which keeps us cool. We also know that as we sweat we lose water, start to dehydrate and will eventually run out of sweat and begin to overheat. This is heatstroke, which can seriously damage or even kill us.
The great thing about training in this country is we can choose not to train on very hot days and avoid such dangers. We know that it will probably be cold and wet again shortly.
Unfortunately, we can’t choose our race days so sometimes we will probably be racing in Arizona like conditions.
Racing in high temperatures
Success starts with understanding, is built on training, and finished with preparation.
You should understand how the body behaves in hot weather. There is a brief explanation here and you can find a more in-depth explanation at Savage Sports website. Click here.
Our body’s temperature regulation system is very sophisticated. We lose heat through three routes; breathing, convection/radiation through the skin and sweating (eveporation). Sweat actually makes the smallest contribution. The bulk of the work is done by blood flowing through capillaries in the skin being cooled by the air around us.
As we get hotter the body diverts more blood to the skin reducing the amount going to the muscles. This reduces the amount of oxygen available to the muscles which then start to use the anaerobic fuel systems which are less efficient and use more fuel. As a result we begin to fatigue more quickly in high temperatures.
As our core temperature rises we begin to sweat to gain the additional incremental benefit of evaporation cooling. This means we begin to dehydrate. This results in the blood thickening and a reduction in blood volume. Thicker blood means the heart has to work harder to push it round the body. As that happens the body diverts further blood to the heart muscle and the system becomes less efficient at cooling us.
Along with the water in our sweat we also lose essential minerals (salts). As well as affecting our physical performance a loss of about 2% of our body weight through sweat affects us mentally; mood, concentration, memory and cognitive ability are impacted.
In most cases the body “self-limits” our performance forcing us to cut down the rate at which we are working to prevent the system failing but we do have the ability to override the self-limiting process. This makes sense; if you are being pursued by a lion slowing down to avoid overheating is not a good idea.
The problem comes when we override it and continue to do so in pursuit of running longer and faster for fun – did I really say “for fun”. When we do that the system can run away, ultimately produce more heat as it attempts to cool us. When that happens we have reached the point when heatstroke can kill us.
Training for heat
The good news is that we can take advantage of hot days to get our bodies to adapt for running in high temperatures. Professional athletes going to a competition in a hot climate will aim to acclimatise for weeks if not months; we don’t have that luxury so we should take advantage of those really hot days.
Just as normal training provokes muscle developments, so training in high temperatures encourages the body to develop more capillaries in the skin and trains them to relax, getting more blood through the skin making the process more efficient. And as the skin becomes a more efficient radiator less blood has to be diverted from the muscles allowing them to operate more aerobically and conserving energy.
Because the process is more efficient we don’t have to rely on sweat to cool us which means we conserve the water, and therefore the salts.
To produce these adaptations we don’t have to run ourselves ragged in high temperatures. Even a small amount will begin to stimulate those changes – so get out and enjoy running on those hot days.
Training Safely and Efficiently in the heat
There is a very useful short guide available from Savage Sports. You a read it and download a copy here. Click here.