08/21/2026
Training in the heat feels harder because it is harder. But understanding why changes how you manage it.
When temperatures rise, your body has two competing priorities. Keep your muscles working and keep your core temperature from climbing too high. Blood gets redirected to the skin to dissipate heat through sweat. That means less blood delivering oxygen to your working muscles. Your heart rate climbs even though your pace hasn’t changed.
Add humidity and that system declines even more. Sweat can’t evaporate efficiently, so the cooling mechanism stalls and core temp rises faster.
The good news is your body can adapt. There are plenty of passive heat adaptation strategies for those who truly want every edge they can get but for the bulk of outdoor athletes, training responsibly in the heat, consistently will be the least time intensive.
The trade off becomes when training quality is sacrificed by the heat itself. Keep efforts within desired ranges to maintain training effects and not dip into overexertion.
Three keys to manage the heat:
- Stay ahead of hydration before you feel thirsty.
- Add sodium, water alone won’t replace what we sweat out.
- And slow down. Your perceived effort is honest in the heat.
Train in the heat to adapt to it, and it can become your biggest advantage.