Harnessing Heat Training in Trail Running and Ultramarathons: How Saunas Can Boost Your Endurance

I recently got to share a sauna session with a new friend named Eric. Eric is a unbelievable fit guy in his 50s who bikes and trail runs. He introduced me to a new concept, heat training after your training session. Endurance athletes aer constantly seek new ways to improve performance, recover faster, and push their limits. Trail running and ultramarathons demand exceptional stamina, mental toughness, and physical resilience. One emerging method gaining attention is heat training, with sauna sessions after your training becoming a popular tool to enhance endurance. This post explores how heat exposure, particularly through sauna use, can complement your training and help you reach new heights in trail running and ultramarathon events.

Sauna sessions for training are best done with friends.

What Is Heat Training and Why Does It Matter?

Heat training involves exposing the body to elevated temperatures to trigger physiological adaptations. These adaptations improve the body’s ability to regulate temperature, maintain hydration, and sustain performance under heat stress. For trail runners and ultramarathoners, who often face varying weather conditions and long hours of exertion, heat training can be a valuable addition to their regimen.

Key benefits of heat training include:

• Improved cardiovascular function: Heat exposure increases heart rate and blood flow, training the heart to pump more efficiently.

• Enhanced sweat response: The body learns to start sweating earlier and more effectively, helping cool down faster during races.

• Increased plasma volume: More blood plasma means better oxygen delivery to muscles and improved endurance.

• Better heat tolerance: Athletes can perform longer in hot or humid conditions without overheating.

  
  

These benefits translate directly to better performance on trails, especially in hot climates or during long ultramarathon events where overheating and dehydration are common challenges.

How Saunas Fit Into Heat Training for Trail Runners

Saunas offer a controlled environment to safely expose the body to heat without the need for outdoor heat or intense exercise. Using a sauna after workouts or on rest days can simulate heat stress and promote the same physiological changes as training in hot weather.

Practical Sauna Use Tips for Endurance Athletes

• Timing: Use the sauna after a training session or on recovery days to maximize benefits without overloading your body.

• Duration: Start with 10-15 minutes per session and gradually increase to 20-30 minutes as your tolerance improves.

• Frequency: Aim for 3-4 sauna sessions per week during your training cycle.

• Hydration: Drink plenty of fluids before and after sauna use to replace sweat losses and avoid dehydration.

• Listen to your body: If you feel dizzy, nauseous, or excessively fatigued, exit the sauna immediately.

  
  

Integrating sauna sessions into your routine can boost endurance adaptations without adding extra running volume, reducing injury risk while improving heat tolerance.

Real-World Examples of Heat Training Success

Several elite endurance athletes and coaches have incorporated heat training and sauna use into their programs with positive results.

• Lars Engebretsen, a sports scientist, highlights studies showing that heat acclimation can improve time trial performance by up to 5% in trained cyclists, a benefit that translates well to endurance running.

• Ultramarathon runners training for races like the Western States Endurance Run or the Marathon des Sables often use heat training to prepare for desert or hot mountain conditions.

• Some athletes report feeling stronger and less fatigued during races after consistent sauna use in the weeks leading up to competition.

  
  

These examples show that heat training is not just theory but a practical tool that can enhance performance in demanding endurance events.

Trail runner taking a break during an ultramarathon in a mountainous heat-exposed environment

Combining Heat Training With Traditional Endurance Workouts

Heat training should complement, not replace, your regular trail running workouts. Here’s how to integrate sauna sessions effectively:

• Use sauna sessions on easy or rest days to promote recovery and heat adaptation.

• Avoid sauna use immediately before intense workouts to prevent excessive fatigue and tank your workout. Sauna is best after a hard session.

• Combine heat training with hydration strategies and electrolyte balance to maintain performance.

• Monitor your body's response and adjust sauna duration or frequency accordingly.

  
  

By balancing heat exposure with your running schedule, you can build resilience and improve your ability to perform in challenging environments.

How and Why It Works

Spending time in a sauna mimics the cardiovascular effect of easy to moderate exercise. Traditionally there is a limit to how much time one person can spend training before injuries start to pile up. Excessive load on the joints, specifically tendons and ligaments, can end up causing strains and tears. However, sauna can allow an athlete to spend more time getting the effects of cardiovascular exercise, without the load on the joints. In a typical sauna session you might elevate your heart rate to that of a jog for 2 or 3 rounds of 15 minutes, without taking a single step.

Safety Considerations and Who Should Avoid Heat Training

While heat training offers benefits, it is not suitable for everyone. People with cardiovascular issues, high blood pressure, or certain medical conditions should consult a healthcare professional before starting heat exposure routines. Pregnant women and individuals prone to heat illness should also avoid saunas or use them with caution.

Always prioritize safety:

• Stay hydrated!

• Avoid alcohol before sauna use

• Exit the sauna if you feel unwell

• Use a thermometer to monitor sauna temperature ideally between 170 deg and 205 deg F.

  
  

Final Thoughts on Using Saunas to Boost Endurance

Heat training through sauna use is a promising method to enhance endurance for trail runners and ultramarathoners. It improves cardiovascular efficiency, sweat response, and heat tolerance, all critical for long-distance performance in varied conditions. When combined with smart training and recovery, sauna sessions can help you push your limits safely and effectively.

If you want to try heat training, start slowly, stay hydrated, and pay attention to how your body reacts. Over time, you may find that the sauna becomes a powerful ally in your endurance journey, helping you tackle tougher trails and longer races with greater confidence.

Take the next step by incorporating sauna sessions into your weekly routine and see how heat training can elevate your trail running and ultramarathon performance.