Exercising in the heat is always hardest when the weather first starts warming up in spring and early summer. It takes your body a while to adapt, but the adaptations happen much faster than you might think. You just need to do the right things to make it happen.
What can you do to make it easier to exercise in the heat?
1. The best way to improve your ability to run or cycle in the heat is to increase your fitness. Fitter people cope much better with the heat than less fit people. This obviously takes time, but if you continue to train consistently then over time, exercising in the heat will begin to feel easier.
2. Train in the Heat: Training during the hottest part of the day (late morning to mid-afternoon) can accelerate adaptation. However, avoid excessive exertion and make sure you listen to your body to prevent heat-related illness. Limit high-intensity efforts and start with lower-intensity sessions during peak heat.
3. Hydrate consistently: Hydration is critical for heat adaptation. You should focus on staying hydrated throughout the day, drinking water or ideally electrolytes. Starting training sessions well-hydrated can help maintain performance and reduce strain on the body.
4. Use Controlled Heat Exposure (Saunas or Hot Baths):
- Spending 10-15 minutes in a sauna after a training session (if available) can extend heat exposure and accelerate adaptations, particularly in the cardiovascular and thermoregulation systems. The sauna mimics heat stress and reinforces the body’s responses to exercising in hot conditions.
- Hot Baths: Sitting in a hot bath for 15-20 minutes post-run can also simulate heat exposure and help the body adapt. Like the sauna, this increases plasma volume and sweat rate without the need for additional training.
5. Adjust Your Diet to Support Adaptation
- Increase Electrolytes Through Food: Include more naturally salty foods, like pickles, or fruits high in potassium, like bananas, to help balance electrolytes. This supports hydration and muscle function, reducing fatigue and speeding adaptation.
- Carbohydrate Intake: Carbohydrates are key for energy, and glycogen stores help with fluid retention. Eating carbs before and after training sessions supports energy levels and recovery, helping the body adapt more readily.
6. Monitor Your Heart Rate and Perceived Exertion
- Track Your Progress: Heart rate and perceived exertion are good indicators of how well the body is adapting. If your heart rate remains high for a given pace/speed over several days, reduce the intensity or duration until it stabilises.
- Use Cooling Techniques: Cooling down with ice packs or cool towels after training can aid in recovery and help to keep heart rate down. Over time, a lower heart rate during and after training is a sign that you are acclimitising.
7. Stay Consistent with Daily Exposure
- Daily Exposure is Key: The body adapts best with consistent exposure to heat. Even if training intensity varies, try to maintain some level of daily heat exposure to avoid losing progress and to maintain adaptations gained from prior sessions.
8. Emphasise Recovery and Sleep
- Rest and Recovery: Adequate sleep and recovery are critical as heat adaptation can be taxing on the body. Quality rest allows the body to recover and strengthen the adaptations made each day, ultimately speeding up the adjustment period.
By following these strategies you should be able to complete the heat adaptation process in around 10 – 14 days, or at the very least, significantly improve it. So if you have an event coming up soon, and you expect it to be hot, employing some of these strategies should be helpful.
What changes occur in your body as you become heat adapted?
Now that you understand the strategies you can use to help your body adapt to exercising in the heat, here is an explanation of the actual physiological changes that happen in your body as you become heat adapted.
It is pretty amazing how good our bodies are at adjusting.
Day 1-3: Initial Responses
- Increased Blood Flow to the Skin: In the early days of heat exposure, your body prioritises cooling by directing more blood to the skin. This helps radiate excess heat but can initially reduce the amount of blood available for the muscles, leading to an elevated heart rate and more perceived effort.
- Elevated Heart Rate and Core Temperature: During your first few training sessions in the heat, you will probably experience a higher heart rates and elevated core temperature, as your body is not yet efficient at dissipating heat. This can result in fatigue and discomfort, signaling your body to begin adapting.
- Enhanced Sweating: Heat exposure also prompts an increase in sweat production. However, your body initially loses more electrolytes in sweat, and sweating may not be as efficient in cooling due to a delay in the sweating response.
Day 4-7: Key Physiological Adaptations Begin
- Increased Plasma Volume: By the end of the first week, your blood plasma volume begins to expand. This increase in fluid volume helps your cardiovascular system maintain blood pressure and deliver adequate blood to both working muscles and the skin. A higher plasma volume supports cooling through better blood flow to your skin, while also reducing the strain on your heart.
- Sweating Efficiency and Increased Rate: Sweating mechanisms improve significantly, and your body will start to sweat earlier and at a higher rate. This helps with cooling your skin more quickly and efficiently. Your body also begins to lose fewer electrolytes (like sodium and potassium) in sweat, which preserves these critical nutrients and reduces the risk of you suffering from dehydration or cramping.
- Reduced Heart Rate: With increased plasma volume and more efficient cooling through sweat, your heart no longer needs to pump as quickly to meet the demands of exercising in the heat. Your heart rate will decrease for a given intensity level, allowing you to train more comfortably and efficiently in hot conditions.
Day 8-10: Further Stabilisation and Improved Temperature Regulation
- Lower Core Temperature: By around day 10, your body becomes more efficient at regulating it’s core temperature. The cooling response kicks in earlier during a training session, and your body maintains a lower core temperature at a given exercise intensity. This adaptation significantly reduces the risk of you experiencing heat exhaustion or heat stroke.
- Enhanced Vascular Adaptation: Blood vessels in your skin dilate more effectively, allowing for better heat dissipation. This adaptation is particularly helpful in humid conditions, where sweating alone might not be as effective due to the reduced evaporation rate. Improved skin blood flow helps you to stay cooler, even in high humidity.
- Reduction in Perceived Effort: With the physiological adaptations underway, training in the heat will begin to feel more manageable. A lower heart rate and reduced core temperature contribute to a reduced perception of exertion, making it easier for you to maintain pace/speed without feeling as fatigued or stressed.
Day 11-14: Full Acclimatisation and Stabilisation
- Optimised Sweating and Thermoregulation: By the end of the acclimatisation period, your body reaches a stable and efficient state of heat adaptation. Sweating becomes fully optimised—starting early, at a higher rate, and with minimal electrolyte loss, ensuring maximal cooling with minimal dehydration risk.
- Improved Overall Cardiovascular Stability: Your body’s cardiovascular responses are now more balanced, allowing for efficient blood flow to both the muscles and skin without excessive cardiac strain. This stability will enable you to sustain your pace and intensity in hot weather conditions.
- Improved Recovery in Hot Conditions: With full adaptation, your body recovers more efficiently after a training session in the heat. By regulating heart rate and cooling more effectively, you will experience less stress and fatigue, which aids recovery and allows for more consistent training.
Summary
A 10-14 day period of acclimatisation will equip you with critical physiological adaptations that make running or riding in hot and humid conditions safer and more sustainable. Enhanced plasma volume, efficient sweating, lower heart rate, improved blood flow, and better temperature regulation all work together to help you perform at your best, even under challenging environmental conditions.
