Contributing writer: Ciaran O’Grady, The Big Chainring, Sports Scientist and Coach at NTT Pro Cycling.

The importance of hydration is stressed at the onset, and then the strategies here are split into two main categories; pre-cooling, which are performed before you start exercise; and per-cooling, which are performed during exercise.


– Hydration

It goes without saying that adequate but not excessive fluid intake is essential for maintaining hydration levels in hot environments. Be attentive to your desire to drink and ensure you have adequate supply of fluids or plenty of opportunity to stop and refill. Dangers occur at the severe ends of the hydration scale; hyperhydration and hypohydration, so be sure to calculate how much fluid intake you might need based on your exercise intensity, weather conditions, hydration status before your ride, etc.

1 — Pre-cooling

– Cold water immersion

Lowering the body temperature before exercise is a great way to improve performance as it lowers the body’s core temperature, meaning more time until your body reaches those higher core temperatures during your ride. To do this, full body immersion in a cold bath is generally the best, but even a cold shower for a sufficient length of time will work.

– Acclimation & acclimatisation

This refers to a slow and steady process of getting your body accustomed to exercising in hot environments, and could take place over the weeks and months before a big event. There are several physiological changes that occur over time, such as increases in sweat rate and better thermoregulation with changes in blood flow. If you usually live in a cold or temperate environment, you can re-create hot and humid environments in a sauna or bathroom with the heat turned up.

2 — Per-cooling

– Cold/Ice water ingestion

Once on the bike, ingesting cold fluids is one of the best ways to slow the increase in core temperature when exercising in hot environments. This can be cooled fluids in your bottles that you take with you, but eventually these will heat up as you ride. Take things further and part-freeze your bottles, so you have slush in them. To slow the heating up of your on-bike bottle fluids, consider investing in a few neoprene beer can covers and use them to insulate the bottles. You may need to have bigger bottle cages if you go down this route; classic metal ones work a treat.

– Cooling packs

Cooling the skin is another way of reducing heat stress and discomfort. As blood circulates towards your skin, it brings hot blood from your core and tries to cool it down towards the surface of your skin. This is challenging in hot environments so having cooling packs or ice bags that you stuff down your jersey can work wonders—a common sight in professional racing.

– Cooling vests

One step up from cooling packs is to use a whole-torso cooling vest. This has the benefit of covering a larger surface area of your skin than a single cooling pack or bag, but has limitations in terms of size and practicality. If your target event requires you to warm up beforehand, this is a great way of managing your core temperature before the event starts.

– Clothing

Not wearing the correct clothing when the temperature increases is a common oversight; this is where sweat-wicking and ventilation properties are extremely important. A thin base layer with an advanced mesh construction and ultralight jersey will help to draw sweat away from the skin towards the moving air as you ride. This also helps to keep your body sweating efficiently as the space next your skin is not saturated with sweat. You want to keep a steady flow of sweat from your skin going towards the environment.

Too much clothing can be a problem as extra layers will provide thermal insulation and reduce the capacity of your body to dissipate the heat generated by your body during exercise. However, note that clothing can also provide a protective layer against the radiation of the sun and associated thermal stress.

– Spraying water/drenching

Spraying water over yourself or dousing your body in water is a simple way of providing extra surface cooling to help your body with effective thermoregulation. This could be an occasional spray of water from your bottle, or a stream or river to dip your legs into for a short period of time.

– Menthol

Using menthol in a topical application or as a mouth rinse can improve performance and reduce perception of heat stress in hot environments. At the moment it is not clear whether this is mainly due to changes in perception of effort related to changes in perception of heat stress or if there is more physiological factors at work. The application of menthol into sports products is slowly increasing, but ASSOS Chamois Crème definitely would add a bit of cooling on a hot day.

Commonly Asked Questions:

“Is pre-cooling or per-cooling better than the other?”

Most of the above strategies have been found to be equally effective in improving exercise performance in the heat.

“Cramps are just caused by dehydration, right?”

The evidence behind dehydration causing cramping is anything but convincing, and it is more likely that the overall physiological load causes neurological challenges that lead to cramps. Heat stress is definitely something that would dramatically add to the physiological load, but recent research has compared the cramping susceptibility of dehydrated and euhydrated individuals and no differences have been found!