How Your Body Regulates Temperature 

Hot weather adds an extra layer of stress to your body when you exercise. Whilst movement is one of the most effective ways to support both physical and mental wellbeing, understanding how your body responds to heat can help you to train smarter. What many people don’t realise is that exercise generates a significant amount of heat. Did you know around 80% of the energy your body produces during exercise is released as heat rather than movement? As your muscles work, they continuously generate heat, causing your core temperature to rise.

To keep your internal temperature within a healthy range (around 37°C) your body activates several cooling mechanisms. Sweating helps heat through evaporation, blood flow is redirected towards the skin’s surface to release heat too and your breathing rate increases to assist with cooling. When temperatures and humidity rise, these systems have to work much harder, making it more difficult for your body to regulate its temperature efficiently.

With regular exercise and appropriate recovery, your body becomes more efficient at responding to physical stress. Understanding these processes will help you make informed training decisions, build resilience and ensure you can continue exercising confidently even when the temperature rises!

What Happens When You Exercise in the Heat?

When you exercise in hot conditions, your body has to juggle two important tasks at the same time: delivering oxygen and nutrients to your working muscles while also keeping your core temperature under control. To do this, your cardiovascular system works harder, increasing blood flow to the skin to help release excess heat while continuing to support the muscles driving your movement.

As a result, you may notice that your heart rate is higher than usual, even when exercising at an intensity that would normally feel comfortable. Workouts can feel more demanding, fatigue may set in sooner and maintaining your usual pace or performance can become more challenging. The body also loses more fluid and electrolytes through sweat, increasing the risk of dehydration, particularly during longer training sessions or periods of prolonged heat exposure.

Even mild dehydration can affect how you feel and perform, influencing everything from endurance and strength to concentration and decision-making. This is why staying hydrated becomes increasingly important when it’s hot.

However, feeling that exercise is harder in the heat doesn’t mean your body is struggling – it means it’s adapting. Behind the scenes, an incredible network of systems is working together to regulate temperature, protect vital organs and maintain performance. 

How Heat Affects Your Muscles

Heat has a complex relationship with muscle performance. On the one hand, warmer muscles generally function more effectively. This is one of the reasons a good warm-up can improve the quality of a workout. As muscle temperature rises, blood flow increases, joints often feel less stiff and communication between the brain and muscles becomes more efficient. The result is often greater mobility, smoother movement patterns and the ability to generate force more effectively.

However, there is a point where rising temperatures can begin to work against you. When your core body temperature becomes too high, physical performance can start to decline. Muscles may fatigue more quickly, exercises can feel harder than usual, and maintaining good technique may become more challenging. You might also notice that weights feel heavier, recovery between sets takes longer, or your usual training pace feels more demanding.

Heat doesn’t just affect your muscles – it also influences the brain and nervous system. As body temperature rises, the brain receives signals that the body is under increasing stress. In response, it may subconsciously reduce the amount of effort you’re able to produce as a protective measure against overheating. This is one reason why a workout that feels comfortable on a mild day can feel significantly tougher during a heatwave, even when you’re performing exactly the same exercises.

Understanding these responses can help you adjust your expectations when training in hot conditions. Feeling slower, more fatigued, or less powerful doesn’t necessarily mean you’re losing progress – often it’s simply a sign that your body is working harder to manage the additional challenge of heat.

Why Strength Training Helps

Although any form of physical activity increases body temperature, resistance training typically places less sustained demand on the cardiovascular system than prolonged endurance exercise. The built-in recovery periods between sets allow heart rate and body temperature to decrease slightly before the next effort, reducing continuous heat stress.

Regular strength training can contribute to better tolerance of hot conditions in several ways. Building and maintaining muscle mass supports metabolic health, as skeletal muscle is essential for blood glucose regulation, energy use and overall physiological function. A body with greater metabolic resilience is often better equipped to cope with high temperatures.

During periods of extreme heat, outdoor endurance activities may become less practical or require significant adjustments. Strength training offers an alternative way to maintain and develop fitness while limiting the prolonged exposure to hot conditions that often accompanies longer aerobic sessions.

Practical Tips for Training in the Heat

Remember that fitness does not make anyone immune to heat-related illness. Listening to your body remains essential – always pay attention to your body and how it is responding.

Some of my tips when exercising in the heat:

• Exercise during cooler parts of the day when possible, seek shade
• Hydrate regularly throughout the day, not just when you’re exercising
• Reduce intensity and allow extra recovery between sets 
• Wear lightweight clothing!

A Final Thought

Training in the heat can feel more challenging, but that doesn’t mean you need to stop moving. By understanding how your body regulates temperature and responds to heat stress, you can make simple adjustments that help you continue exercising safely and effectively. Remember, your body is incredibly adaptable! With consistent strength training, good hydration and adequate recovery, you’re building a stronger, more resilient foundation that supports you all year round.

As always, if you have any questions please do get in touch.

Caroline x