How does heat effect training, racing, performance and becoming more heat adapted for endurance athletes.
Marginal Gains

The Effect of Heat on Performance

“If you can’t handle the heat, stay outta the kitchen.” Or, just spend more time in the kitchen? Heat is a tricky thing to tackle when it comes to endurance events. It’s an uncontrollable, inescapable part of competing certain times of the year and in certain locations.

Excessive heat (or more specifically the inability to handle it) can lead to an increase in overall core temperature and just a few °F can turn things downhill quickly. The brain starts to realize that there are more important things to maintain than you pushing hard on the pedals and it will try to put a stop to that.

Overall, heat stress will reduce the ability to achieve maximal metabolic rates during exercise. Cardiac drift is common term for the increase or “drift” of your heart rate upwards over the duration of an effort/event and is expedited with dehydration or heat. Often, this dance with the discomfort of heat is manageable over the duration of a training session or short event. However, if gone unaccounted for, it can lead to a drastic drop in performance.

Things may start with just discomfort and an annoyingly hot feeling…typically if you are equipped to handle it then it will stay that way and you can micromanage it. If you can’t, then some dizziness, nausea, and/or waning ability to really focus on the task at hand can follow.

Below, I’ll dive into ways to manage the heat from a micro (short term) perspective around racing or training + from a more macro (big picture) perspective.

Micro-Managing the Heat

There are many things we can do to mitigate the effect of heat. In the lead up to the big event/workout/race, it’s important to think about your prep 3, 4, 5 days prior.

Firstly, hydration cannot be neglected during these days and a greater importance should be placed on electrolytes. The "preload" idea behind this is to increase the essential minerals we need and that especially being sodium; as sodium levels in the body rise, water will follow and saturate the muscles. I always stick some Skratch Labs Hydration Mix in the bottle regardless of the training on tap that week.

Thus, if we slowly increase these minerals we will “hold onto” more fluid in our cells over time. Yeah, you may gain a little water weight but SO WHAT if it means mitigating the harmful effect of heat. This is when I keep a bottle with electrolytes on me at all times. Choose low calories options that aren't neccesarily full of sugar. I like the options from LMNT, Nuun, and SOS.

On race day, keep all your bottles, fuel, etc as cool as you can and try to buffer heat through cooling vests, staying in the shade, and less aggressive warm up routines.

PRO TIP: fill pantyhose with ice and stick them in your jersey collar while getting ready.

Macro-Managing the Heat

Acclimatizing [“uh-kli-muh-tizing”)

From a bigger picture, and longer timeline, you can prep for key events by acclimatizing to the heat. If it’s during the warmer months or you are in a warmer climate, try moving some of those light-to-moderate workouts towards the warmer part of the day….gradually. Be careful here, if you start stacking long or hard days in the heat you may suffer the consequences with poor recovery.

If it’s the winter months (as my Puerto Rican race trip pictured above) you can leverage sitting in a sauna and/or moving some of your workouts indoors (without cooling options) to get acclimated.

For the sauna protocol, this looks like: 7+ days of 20-30min sauna sessions around 180°f if possible. Ideally immediately following training, you hop in the sauna as quickly as possible. Then slowly rehydrate through the day. This should be wrapped up about a week before your event. (Check this article out for a scientific review…)

ASIDE: There is also a heavy amount research that supports using heat acclimation from a sauna to prepare for altitude exposure. In fact, the same thermal stress can trigger these adaptations advantageous to altitude events.

Here’s What’s Happening

Heat acclimation typically takes around 10-14 days depending on variables. During this time, your body will be learning how to send more blood to the skin quicker, in greater amounts, and more efficiently. One big reason for this is due to the increase in plasma volume in your blood (the fluid part). These processes lead to more liquid coming to the skin which cools you through convection. As you begin to get more acclimated, this typically induces more sweating but less mineral/sodium loss.

Additionally, your body’s entire cardiovascular system becomes more responsive and efficient when it encounters this heat stress and the hormonal system is becoming more adapted to this “new normal”. Even performing in moderate or temperate condistions see a boost from this protocol.

The Health Effect

Not only do we see profound improvements in performances, the impact on general cardiovascular health is also very important as humans. Routine sauna usage, exposure to heat, and challenging the body under this type of stress can improve the efficiency and function of our system to dilate, move fluid, and operate. Something we should all be wanting regardless of performance.


Avatar Carson Beckett

Carson Beckett / Thursday, May 5, 2022