Endurance · 2 min read
Sweat rate tells you how much fluid your body loses per hour during exercise. For athletes training for 60 minutes or more, this number matters more than most people realise.
By Chris Gkoufas, DVOTION ·
Sweat rate is calculated by measuring body weight before and after exercise under controlled conditions. The difference in weight — accounting for any fluid consumed during the session — gives an estimate of fluid lost per hour.
At DVOTION, sweat rate measurement is included as part of VO₂ max testing. It adds minimal time to the session and gives data that directly informs hydration strategy.
Sweat rates vary dramatically between individuals. A heavy sweater can lose 1.5–2.5 litres per hour during intense exercise in warm conditions. A low sweater might lose half that. Generic hydration guidelines do not account for this variation.
For endurance athletes — particularly those competing in heat, at marathon distance or above, or in multi-sport events — an accurate sweat rate helps build a specific fluid intake strategy rather than relying on "drink when thirsty" or fixed volume guides.
Sweat rate data gives you a starting point for calculating fluid targets in training and racing. Combined with environmental conditions and exercise intensity, you can set fluid targets from your own losses rather than from a general recommendation.
It also informs decisions about electrolyte replacement, since sweat contains sodium, chloride and other minerals. Higher sweat rates typically mean greater electrolyte losses — relevant for performance and cramp risk management.
Yes. Better-trained athletes tend to sweat more efficiently — they start sweating sooner and distribute it better — but individual sweat rate varies significantly and is also influenced by genetics and heat acclimatisation.
Sweat rate can change with fitness, body composition, heat acclimatisation and seasonal conditions. Retesting annually or alongside VO₂ max retests is a reasonable approach.
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