Should Athletes Still Take Rest Breaks Even if They Have Access to Fluids Throughout Activity?

On the surface, rest periods during physical activity appear to be used for the sole purpose of rehydrating to avoid dehydration. Following this logic, if athletes have access to fluids throughout activity, then rest or “hydration” breaks are not required. However, even when fluids are readily available during physical activity, voluntary fluid consumption by some athletes consists of only half of their body mass loss. This difference in body mass is primarily attributed to fluid loss resulting in voluntary dehydration. 1 For every percentage decrease in body mass due to dehydration, the rate of body temperature rise during exercise can increase up to ~0.25°C above rates of euhydrated individuals. 1 Moreover, if exercise intensity is high or environmental conditions are extreme, body temperature will rise despite adequate fluid intake during activity. Thus, the risks of dehydration and/or hyperthermia increase when rest periods are not taken during physical activity. It is well established that dehydration and/or hyperthermia increase the risk for exertional heat illness and reduce sport performance. 2-4 It is clear that rest breaks during physical activity are key components in the prevention of dehydration, performance decrements, and heat-related injury. 2.