Heat is a performance variable in its own right. Here's how to prepare, fuel and hydrate when the temperature climbs.
Heat is a performance variable in its own right. Here's how to prepare, fuel and hydrate when the temperature climbs.
Heat is one of the most significant and underestimated variables in sport. As the temperature rises, your body has to work harder to stay cool, your sweat losses climb, and your performance can suffer well before you consciously feel that the heat is a problem. A plan that works in cool conditions can unravel in the heat, usually at the worst possible moment.
Whether you are training through a hot spell or targeting a race in a warm climate, understanding how heat affects you, and preparing for it, protects both your performance and your wellbeing. Here is how.
When you exercise in the heat, your body diverts blood to the skin to dissipate heat through sweating. This increases your fluid and electrolyte losses and can reduce the blood available to your working muscles and your gut, which is why hot conditions make exercise feel harder and can compromise fuelling.
The result is a combination of higher hydration needs, greater cardiovascular strain, and a gut that may be fussier about absorbing fuel. Recognising these effects is the first step to managing them.
In the heat, hydration moves to the front of your strategy. Start sessions and races well hydrated, drink steadily to match your elevated sweat losses, and take on fluid in regular, manageable amounts rather than large gulps. Both under-drinking and over-drinking cause problems, so aim for a sensible, responsive intake.
Because sweat losses are so much higher in the heat, staying on top of hydration requires more attention than in cool conditions. It is far easier to maintain hydration than to recover from a deficit once you are already behind in the heat.
You lose considerably more sodium through increased sweating in the heat, and replacing it alongside fluid helps you maintain fluid balance and performance. How much you need depends on how much you sweat and how salty your sweat is, both of which vary between individuals.
In hot conditions, electrolyte products like HYDRO tablets move from optional to a genuine part of the plan, especially for heavy or salty sweaters. Managing sodium is central to hydrating effectively when it is hot.
Because heat can reduce blood flow to the gut and make it more sensitive, the carbohydrate intake you tolerate comfortably in cool conditions may feel harder when it is hot. The demand for carbohydrate has not changed, but how you deliver it may need care.
Favour formats and concentrations you know your gut handles well, be slightly conservative with new or very high intakes on a hot day, and rehearse your fuelling in similar conditions. Well-formulated sports drinks and gels are designed with absorption in mind, which helps in the heat.
If you have a hot event coming up, one of the most effective things you can do is acclimatise by training in similar conditions where possible. Over a period of around one to two weeks, your body adapts, improving your sweat response and your tolerance of the heat, so that the same conditions feel less punishing.
Acclimatisation also lets you rehearse your adjusted hydration and fuelling, so nothing is a surprise on the day. Where genuine heat is not available, other approaches to heat exposure can help, but the principle is to prepare rather than hope.
Beyond performance, heat carries genuine health risks if ignored, and pushing hard in extreme heat without proper preparation and hydration can be dangerous. Listen to your body, moderate your effort when conditions are severe, and prioritise cooling and hydration.
Sensible preparation lets you perform well in the heat while respecting its risks. The athletes who cope best with heat are the ones who plan for it rather than treating it as an inconvenience to push through.
In the heat, prioritise hydration, replace sodium generously, adjust your fuelling with a fussier gut in mind, and acclimatise where you can. Start well hydrated, respect the health risks, and rehearse your hot-weather approach in advance.
Heat rewards preparation and punishes improvisation. Plan for it properly and you can perform strongly when others are wilting in the same conditions.