Preparing for the heat: the keys to acclimatization to improve your sports performance

In the world of sport, performance is often about the details. Savvy athletes know that to maximize their potential, it's not enough to train hard, you also have to train smart. One of the major challenges for athletes is to maintain a high level of performance in extreme conditions, particularly during periods of intense heat. Heat acclimation then becomes a crucial skill. This ability to adapt your body to high temperatures can mean the difference between exceptional performance and premature retirement. In this article, we discuss the mechanics of heat acclimation, its benefits, and how athletes can optimize their preparation to excel even under the blazing sun.

1. Understand heat acclimation

L'heat acclimatization refers to the set of physiological processes by which the body gradually adapts to high temperatures. This allows athletes to maintain, or even improve, their performance despite unfavorable thermal conditions.

Let's talk a little physiology, when the body is repeatedly exposed to high temperatures, it undergoes several beneficial physiological changes:

1. Increased sweat production : Sweating becomes more profuse and occurs at lower body temperatures. This helps cool the body more effectively.
2. Change in the composition of sweat: Sweat becomes less concentrated in electrolytes, reducing the loss of essential minerals like sodium and potassium.
3. Improved blood circulation : Blood flow to the skin increases, facilitating heat dissipation.
4. Decreased heart rate: By becoming familiar with the heat, the heart beats more slowly for the same level of exercise, reducing heart fatigue.
5. Stabilization of body temperature: The body manages to maintain a lower temperature despite heat exertion.

These adaptations typically occur over a period of 7 to 14 days of regular heat exposure, although some changes may continue to develop over several weeks.

2. Benefits of heat acclimation for athletes

Performance improvement

Heat acclimation can significantly improve sports performance. Several scientific studies have shown that athletes who acclimatize to heat can improve their endurance, strength and speed.

1. Increased Stamina : A study conducted by Lorenzo et al. (2010) showed that cyclists who completed a 10-day heat acclimation program improved their race time by 8% on average in hot conditions. Additionally, they also showed a 6% improvement in temperate conditions, indicating that the benefits of acclimation are not limited to warm environments.
2. Improved strength and speed : In another study, Racinais et al. (2015) observed that athletes who acclimatize to heat increase their blood volume and reduce their heart rate, which improves muscle oxygenation and allows for better sprint and strength performance.

Reduced risk of heat-related injuries and illnesses

Heat acclimation can also reduce the risk of heat-related injuries and discomforts, such as heatstroke and dehydration.

1. Heatstroke : The study by Garrett et al. (2011) demonstrated that heat acclimation allows the body to better regulate its temperature, thereby reducing the risk of heat stroke. Acclimated athletes have lower body temperature and better heat tolerance during intense exercise.
2. dehydration : Research by Wingo et al. (2012) showed that athletes acclimated to heat lose fewer electrolytes in their sweat, which helps maintain better fluid balance and reduces the risk of severe dehydration.

Psychological adaptation

Heat acclimation not only benefits the body, but also the mind. Learning to manage heat stress is crucial to maintaining athletic performance.

1. Mental tolerance : A study by Patterson et al. (2014) revealed that athletes acclimated to heat develop better mental tolerance to heat stress. These athletes show reduced perceptions of fatigue and discomfort during exercise in heat, allowing them to maintain sustained effort for longer.
2. Reduction of perceived stress : Another study by Chalmers et al. (2016) found that heat acclimation can reduce levels of perceived stress in athletes, helping them feel more confident and prepared for competition in hot conditions.

In summary, heat acclimation offers significant benefits for athletes, including performance improvement and better psychological adaptation. These benefits allow athletes to optimize their preparation and perform at their best level, even in extreme heat conditions.

Example of a Study on Heat Acclimatization in Runners

A notable study conducted by Garrett et al. (2012) focused on the effects of heat acclimation on the performance of long-distance runners. This research included a group of 20 trained runners who were exposed to a heat acclimation program for 10 consecutive days. Participants ran on a treadmill under controlled heat conditions (approximately 40°C with 40% relative humidity) for a progressive duration, ranging from 30 minutes on the first day to 90 minutes on the last day.

Study Results

1. Performance Improvement: The results showed a significant improvement in runners' performance. After the acclimatization period, the runners reduced their running time by 5% on average over a distance of 10 km compared to their performance before acclimatization.
2. Physiological response: The study also observed notable physiological adaptations, such as a reduction in average heart rate of 10 beats per minute and a drop in average core temperature of 0,5°C during exercise. These adaptations indicate a better thermoregulatory capacity, allowing runners to maintain a higher intensity of effort without overheating.
3. Heat tolerance: Runners also reported improved heat tolerance, with reduced feelings of fatigue and thermal discomfort. This is supported by subjective measures, where participants reported feeling more comfortable and able to sustain prolonged efforts in hot environments.

Implications of the Study

The study of Garrett et al. (2012) demonstrates that heat acclimation can significantly improve the performance runners in high thermal conditions. By adapting their training program to include regular sessions in the heat, runners can not only improve their race times, but also reduce the risk of overheating and dehydration. These results are particularly relevant for summer competitions or in regions with hot climates, where heat management becomes a crucial factor for sports performance.

3. Heat acclimation methods

Heat acclimatization is a crucial step for athletes wishing to maintain and improve their performance in hot environments. Here are several proven methods to promote this acclimatization.

Specific training

Training in hot conditions

The goal is to expose the body to high temperatures in a manner progressive. To do this, gradually increase the duration and intensity of training sessions in hot environments. For example, start with sessions of 30 minutes and increase to 60 minutes. Be careful, hot conditions are not usual for the body, bring water (lots of water).

Interval workouts

This type of training helps improve heat tolerance while increasing the intensity of the exercise. Alternate between periods of intense effort and periods of recovery in a warm environment. This makes it possible to maximize the physiological adaptations. You can do 3-minute high-intensity running intervals followed by 3 minutes of passive recovery, repeated several times in a warm environment.

Passive acclimation techniques

Saunas and hot baths

This technique uses the passive heat to accustom the body to high temperatures. After your workouts, spend some time in a sauna or hot bath. Start with sessions of 10-15 minutes and gradually increase to 30-40 minutes. This method allows you not to interfere with the intensities planned for training. For example, you can go in the sauna for 3x10 minutes after a workout to promote sweating and thermal adaptation.

Nutrition and hydration

Adequate hydration

In hot conditions, the objective is simple: maintain water balance and avoid dehydration. One should consume sufficient amounts of water before, during and after workouts. You can use drinks electrolytes to replace minerals lost through sweating. To give you an idea, you can drink 500 ml of water 2 hours before exercise, then 200-300 ml every 20 minutes during exercise, and replenish lost fluids after training.

Electrolyte supplements

The electrolytes are the minerals that circulate in the blood: sodiumium, potassium, magnesium and calcium. During physical exercise we lose these minerals through excessive sweating. To prevent these imbalances, you should use supplements containing sodium, potassiumum, magnesium and calcium. The choice is wide, choose either electrolyte tablets or sports drinks specially formulated for hot environments.

. Case studies and testimonials

Karoly Spy is a trainer specializing in endurance sports for over 20 years. Passionate about the scientific approach to training and exercise physiology. He is

also a triathlete, which allows him to combine his personal practice, his experience as a coach in the field and scientific knowledge to offer the best to his athletes (amateurs and professionals) whom he supports in their performance project.

He prepared many of his athletes for Hawaii, the Ironman world championship. And he shares his experience with us.

On average, the ambient temperature in Hawaii at this time of year rises to ~30° with a humidity level >50% (generating a felt temperature of +5-6°). Consider that this type of thermal environment induces on average a loss of ~2%, ~7% and ~16% for exercise durations of ~6min, ~30min and ~70min, respectively. So imagine the decline in performance for an Ironman in heat if you are not prepared for it...?
Heat acclimatization is one of the keys to performance on the Hawaiian IM, it reduces thermal tension during exercise, potentially improving performance. For this, nothing could be simpler! Try three weeks before the competition to carry out your sessions at low intensity in a room heated to a temperature of 30°C, and this for >60min at a rate of 3 times/week. If you take it gradually and stay attentive to your sensations (no overload!), then you will teach your body to better tolerate (mental!) and evacuate (physiology!) the heat it stores during exercise. . After 10-12 sessions (without too much gap between them), you will see for yourself how effective this heat acclimatization strategy can be...

With the athletes I coach, we use an alternative approach by taking post-exercise hot baths to better tolerate humid heat. The advantage of the post-exercise hot bath is that it does not interfere with the workout and is easy to incorporate into the preparation. To obtain a complete acclimatization In heat, it is important to raise both core body temperature and skin temperature. Taking a hot bath post-session allows for this combined rise in core body temperature and skin temperature. Heat cannot dissipate in the moist heat of the bath, which improves the specific mechanisms foracclimatize to humid heat.

5. Practical advice for athletes

To take full advantage of the benefits of heat acclimation and optimize your performance in hot conditions, here are some practical tips to follow.

Acclimatization planning

Start early! Give your body enough time to adapt to the heat before a competition or intense training period in the heat. Start it acclimatization process at least 3 weeks before the event foreseen. Gradually increase the duration and intensity of your workouts in the heat. For example, if you are preparing for a race in the summer, start with light workouts in the heat two to three times a week, then gradually increase the frequency and intensity.

Integrate regular sessions to maintain and reinforce the acquired physiological adaptations. One or two sessions per week are enough to maintain once you are adapted.

Mistakes to avoid

Don't neglect hydration ! Absolutely avoid dehydration, which can impair performance and increase the risk of heat stroke. Consume water and electrolyte drinks before, during and after training.

To prevent overexertion, gradually increase the intensity and duration of your heat sessions. Listen to your body and adapt your efforts according to your sensations. Start with sessions of 30 minutes at moderate intensity and gradually increase until 60 minutes.

Monitoring and adjustment

Monitor your body's adaptations and adjust your sessions accordingly. Today, we have access to tracking tools like heart rate monitors, body thermometers, and hydration tracking apps. It is best to note your heart rates at rest and during exercise, as well as your body temperatures before and after training to observe changes.

Adapt your training based on your body's reactions :

We strongly advise you to adjust the intensity, duration and frequency of your workouts in heat based on your feelings and the data collected. By listening to your body, you ensure optimal adaptation and avoid overload.

If you notice excessive fatigue or signs of overheating, reduce the intensity or duration of your sessions and increase recovery periods.

Acclimatization Heat protection is an essential part of the preparation of athletes, especially those who train and compete in hot environments. By understanding the physiological mechanisms underlying acclimatization and by applying specific training methods, passive acclimation techniques, and proper nutrition and hydration, you can significantly improve your performance and tolerance to heat.

Scientific studies clearly show that athletes who take the time to acclimatize can not only improve their enduranceTheir strength and their speed, but also reduce risks such as heatstroke and dehydration. Moreover, acclimatization in heat helps build mental tolerance to heat stress, allowing athletes to maintain sustained effort for longer.

By carefully planning your acclimatization, avoiding common mistakes, tracking and adjusting your progress, and using proper recovery techniques, you can optimize your performance and reduce the risks associated with heat.

References

1. Lorenzo, S., Halliwill, JR, Sawka, MN, & Minson, CT (2010). Heat acclimation improves exercise performance. Journal of Applied Physiology, 109

2. Racinais, S., Periard, JD, Karlsen, A., & Nybo, L. (2015). Effect of heat and heat acclimatization on cycling time trial performance and pacing. Medicine & Science in Sports & Exercise, 47

3. Garrett, A.T., Creasy, R., Rehrer, N.J., Patterson, M.J., & Cotter, J.D. (2011). Effectiveness of short-term heat acclimation for highly trained athletes. European Journal of Applied Physiology, 111

4. Wingo, JE, Lafrenz, AJ, Ganio, MS, Edwards, GL, Cureton, KJ (2012). Cardiovascular drift is related to reduced maximal oxygen uptake during heat stress. Medicine & Science in Sports & Exercise, 44

5. Patterson, M.J., Stocks, J.M., & Taylor, N.A. (2014). Whole-body heat acclimation and the subsequent decay in trained and untrained males. Journal of Thermal Biology, 44

6. Chalmers, S., Esterman, A., Eston, R., Bowering, KJ, & Norton, K. (2016). Short-term heat acclimation training improves physical performance: A systematic review, and exploration of physiological adaptations and application for team sports. Sports Medicine, 46

7.  Garrett, A.T., Creasy, R., Rehrer, N.J., Patterson, M.J., & Cotter, J.D. (2012). Effectiveness of short-term heat acclimation for highly trained athletes. European Journal of Applied Physiology, 112(5), 1827-1837