Why Is Milk White?: & 200 Other Curious Chemistry Questions (2013)

What kinds of chemicals do athletes drink before they do a race?

There are a number of supplements marketed to runners and cyclists to improve performance during races. How much they actually help may be more of an indication of the diet before the race or during training and of the mental state of the athlete than of any special powers of the ingredients. In other words, if the athlete is missing something, adding it back should help. And if the athlete believes the supplement will help, then the placebo effect (deceiving her into feeling better) may also improve performance.

Taking a lot of supplements before a race can actually harm performance if they cause digestive upset or other problems, and many of the supplements used have several negative side effects. A lot of coaches and professionals recommend doing nothing special for a race, only what you normally do during training.

Without making any recommendations or encouraging the use of supplements to improve performance, I can describe some of the supplements used and their claimed benefits.

Sodium phosphate or sodium bicarbonate is taken to buffer the lactic acid that builds up in muscles that are working without sufficient oxygen. Loading up on these before a race can cause digestive problems that lower performance.

Caffeine is taken as a stimulant. Drinking a couple cups of coffee is safe, but caffeine is a urinary stimulant, and stopping to pee will affect your race time.

Antioxidants such as vitamin E, beta carotene, selenium, and vitamin C are safe (though you can overdose on selenium, which affects insulin) and may help prevent some damage caused by strenuous exercise, but they won’t help your performance in the race itself. And using too much may cause stomach upset.

Some people take supplements that relax the artery walls (vasodilators) under the impression that opening up the arteries increases blood flow to the muscles. But your body regulates your blood pressure carefully to make sure there is enough oxygen to the brain, and fainting during a race will affect your time. Being lightheaded generally does not improve performance in any activity, except possibly sleep. Combining vasodilators with dehydration is not a good idea.

Getting adequate salt for a long race can help prevent cramping. Some racers add magnesium and calcium as well. Loss of these electrolytes through sweat is one cause of cramps.