Three ways to exercise safely in extreme heat

With Europe in the grip of summer heat, Team Danmark physiologist Peter Møller Christensen offers three practical tips for staying active in temperatures around 30°C, aimed at those already accustomed to exercise and properly hydrated before starting.

First, prioritise cooling. Just as a car needs coolant to avoid overheating, the body requires active cooling during exertion. Simple methods include filling nylon socks with ice and placing them under clothing or securing them to a shirt’s straps, as seen in the Tour de France. Cold water can also be used for external cooling—more critical than drinking during shorter sessions, though hydration remains essential for longer workouts. Wearing light, breathable clothing and avoiding dark colours helps as well.

Second, pre-cool with slush ice. A 500ml slush ice consumed in small amounts starting 30 minutes before exercise can lower core temperature by half a degree, delaying the point at which heat feels critical. This method, tested during the 2008 Beijing Olympics and used by cyclist Filippo Ganna during his 2022 hour record, is effective enough to justify investing in a slush ice machine—or simply using finely crushed ice.

Finally, adjust expectations. Extreme heat demands a slower pace and lower performance. Accepting this reality, rather than fighting it, makes training more sustainable. The body adapts quickly—improvement can be noticed within a week—though it’s never pleasant. For an easier solution, train during cooler parts of the day.