Core body temperature in exercise and sports
What you need to know
Core body temperature is more than just a number—it’s a key signal of how your body is adapting to physical stress. It plays a critical role in performance, recovery, and overall function. Understanding how your body regulates heat during activity—and what happens when it strays from the ideal range—can help you train smarter, especially in extreme environments.
Core Body Temperature
temperature of your organs, including your heart, brain, and muscles. The average resting temperature is around 98.6°F (37°C), but during physical activity, this can rise as your body generates heat.
Your body uses thermoregulation to maintain a healthy internal balance. This process supports muscle function, enzyme activity, and circulation—but it can be challenged by intense exercise, high temperatures, or dehydration.
How Exercise Affects Core Body Temperature
As your muscles work, they generate heat. Your body activates built-in cooling mechanisms to manage this:
Sweating: Evaporates from the skin to help cool down
Increased blood flow to the skin: Transfers heat outward
Elevated heart rate: Helps move heat to the skin’s surface
These systems are effective—but not limitless. Heat, humidity, and low hydration can impair them, making heat harder to manage during prolonged activity.
Core Body Temperature at Different Stages of Exercise
Optimal Range
97°F–99°F (36.1°C–37.2°C)
Performance: Peak muscle and energy system efficiency
Tips: Maintain this range with steady pacing and hydration
Elevated Range
99°F–101°F (37.2°C–38.3°C)
Performance Impact: Slight strain; sweating and heart rate increase
Tips: Hydrate regularly and monitor intensity
High Range
101°F–104°F (38.3°C–40°C)
Performance: Fatigue, reduced endurance, possible cramping
Tips: Pause for cooling, hydration, and recovery breaks
Critical Range
Above 104°F (40°C)
Performance: Rapid decline; confusion or disorientation may occur
Tips: Stop activity, seek shade or cooling, and hydrate—intense heat may require professional medical attention
Training in Cold Weather
In cooler climates, core body temperature can drop if your activity doesn’t produce enough heat to match the cold.
Tip: Wear layers that retain heat but allow for moisture wicking to avoid rapid cooling from sweat
Watch for: Shivering, slowed reaction time, or confusion—signs your body may be cooling too much
Learn more about the Science
This page is for general educational purposes only and does not provide medical advice or diagnosis. Always consult a healthcare provider for individual concerns related to heat, cold, or exercise safety.