It is the hottest part of the year and athletes need to take the necessary steps if they are not to suffer a deterioration in performance. There are several factors to consider, here are just some of them. Correct nutrition is fundamental to keeping the body well fuelled but, at the same time, agile and light. Focus on fruit, vegetables, fibre and whole foods. Hydration should be adjusted according to the humidity level and the duration of the activity in question.
It is important to begin any training session fully hydrated, although this should not be overdone. During the run, it is a good idea to replace liquids lost, preferably just with water or with rehydrating drinks (well diluted). As a benchmark, on a particularly muggy day, drink a glass of water every 15-30 minutes.
In terms of clothing, make sure you wear light-coloured and highly breathable clothes which leave large areas of your skin uncovered to allow for good ventilation, therefore helping your body to cool quickly.
As regards training sessions, try to find time during the cooler parts of the day (first thing in the morning or in the evening), routes which are sheltered from direct sunlight and/or which are airy (e.g. forests, tree-lined avenues, etc.) and create sessions which do not involve excessive energy consumption. When you have longer sessions planned in hot weather, you should take precautions, ensuring you are not caught out. In these circumstances, you may require sun cream, a hat, a bottle belt, sunglasses, etc. The issue, even in this brief summary, is clearly a very complex one, so be very careful when training in the heat and never underestimate the risks it brings.