How do temperature and humidity affect outdoor sport performance and safety?

• A. They do not affect performance
• B. They improve thermoregulation
• C. They can impair thermoregulation and hydration
• D. They only affect equipment selection

Answer: (C)

Environment shapes how the body cools itself and stays hydrated. When outdoor temperature is high, the body relies on sweating and evaporation to lose heat. But humidity makes sweat evaporate more slowly, so cooling is less effective. That means core temperature can rise more quickly during activity, and the cardiovascular system works harder to pump blood to the skin for cooling. At the same time, fluid loss through sweat increases the risk of dehydration, which reduces blood volume and further impairs performance and heat dissipation.

Together, higher temperature and humidity can slow endurance, increase fatigue, and raise the risk of heat-related illnesses like heat cramps, heat exhaustion, and heat stroke. So these conditions can impair both thermoregulation and hydration, posing real safety concerns for outdoor sport. The statements that they don’t affect performance, that they improve cooling, or that they only influence equipment don’t fit the actual physiology or safety needs.