Tips for training and racing in the heat


The hot summer days are upon us so it’s a good idea to be ready for training in the heat since not being prepared can seriously affect your training and performance.

Why is training and racing in the heat potentially harmful for athletes?

For a long time we thought that heat stress and heat stroke were simply the imbalance of heat loss from the body during exercise in the setting of high air temperatures – the body can't cool itself well enough in the hot temperatures and hyperthermia sets in. We now know that the stress of heat in athletes is more complex than that.

In conjunction with the imbalance of heat regulation in the body, heat stress and ensuing heat stroke, also involve an inflammatory cascade. This inflammation is felt to be primarily mediated by the gut. Since so much blood is diverted away from gut and to the muscles during exercise the tissue of the gut becomes “leaky.” This allows toxins to cross into the bloodstream resulting in a process called endotoxemia. Exercise-induced endotoxemia is now felt to be one of the primary causes of hyperthermia in athletes.

The release of toxins into the bloodstream and the subsequent increased core body temperatures not only contributes to gastrointestinal symptoms in athletes but results in impaired performance through decreased strength and mental fatigue. And if that weren’t enough, endotoxemia can weaken an athlete’s immune system leaving you more susceptible to overtraining and illnesses (this is why there is a higher rate of respiratory infections among high intensity athletes)!

So what can you do to prevent heat related stress and impaired performance?

Here are a few suggestions for before, during, and after your training session or race:


  1. The obvious: sunscreen, light colored clothing, and being fully hydrated

  2. Pre-cooling: drink ice water or turn a pre-training drink into a slushy

  3. Don’t use ibuprofen or aspirin: these drugs can increase the gut’s “leakiness” causing even more problems.

  4. Probiotics: studies have shown that probiotics can reduce the amount of inflammation and endotoxemia that results from stress of exercise and the heat. Probiotics have also been shown to increase run time to fatigue in the heat.


  1. If you're not in a race, take more frequent stops to refill your water bottles. For really hot days you may need to consume at least double your normal water intake!

  2. Don’t forget about salt! Read my tips on salt intake here.

  3. Cold sponges or ice packs: Cyclist and runners could take this tip from triathletes who stuff cold sponges into their jerseys to keep them cool. While I’m riding I like to put small sponges in my arm pits or near the femoral artery since these areas are closer to blood vessels. Otherwise, pouring water over yourself is always an option.

  4. Be aware of pacing: as the heat rises your muscle activation and subsequent power output may diminish – adjusting accordingly will be important so you don’t blow up too soon.


  1. Dunk yourself in an ice bath or if that’s not available drape cold towels over you.

  2. Keep drinking: Just because your workout is finished doesn't mean you should stop hydrating. On those hot days your best bet is to weigh yourself before and after your workout and drink that amount over the next 24 hours (1kg roughly equals 1L of water).

Just like your races, performing well in the heat comes down to being prepared.