Mark Allen on running in heat

Running in the heat does indeed help you by adapting your body to exercising in hot climates. One of the physiological changes that will happen to help you out is that the blood proteins change in a way that makes it easier for the blood to move through your veins. This occurs fairly quickly, within the first 7-10 days of training in heat. Any adaptation after that happens is psychological.

The downside to heat training is that you just won't be able to run as fast as you would in cooler weather, especially if you are trying to stick to specific heart rate training zones. So while training in the heat is good for getting you ready to race it, the pace you will be able to train at won't allow you to develop the same speed as you would in cooler weather. This means that you will run slower and work your muscles less.

The solution is to mix your running workouts up so that some are done in heat and some at cooler times of the day if that is possible. A general rule of thumb is to try to do about half of your short to moderate runs in heat and half at cooler points of the day, and then only about a quarter of your long run workouts in heat and the rest when cooler. This will give you both heat adaptation as well as running at more normal speeds. Doing all of your workouts in heat will not only drag your overall training speed down, but put you at risk of becoming chronically dehydrated, neither of which are good for athletic performance.

Racing in heat is a second issue that we all have to understand. Again, your pace in heat is going to be slower than at cooler races no matter how fit or heat adapted you are. This brings up the topic of expectation. If can you go into a hot race knowing that the experience, especially on the run, will not be the same as in cooler races, you will then be able to gain positive optimism from having a great hot weather race at hot weather paces.

However, if you go into the race expecting to run with the same feel and pace of a cooler day, the actual hot weather race experience will seem like you are having a very poor performance when in reality you could be having the race of your life! The takeaway lesson here once again is to alter race expectations to match the conditions.