Using Heat to Enhance Endurance Performance and Strength Gains

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Athletes — recreational or professional — are always looking for ways to gain an edge.

Recovery technology, nutritional supplements, and training devices have all been developed to help athletes get more out of their body and their training regimen. Even those who exercise for general health can still benefit from many “performance-enhancing” devices and products.

But when it comes to improving performance, sometimes the simplest strategies can be the most effective. For a long time, we have known that heat therapy can be beneficial for health — regular sauna use or hot-water immersion (think spa or hot tub) have been shown to improve cardiovascular health by lowering blood pressure and improving blood vessel function.

Regarding exercise, heat training is known to improve endurance exercise performance by boosting plasma volume. If you’ve ever trained in the humid summers of Florida (trust me on this one), you’ll know this phenomenon quite well.

We know that muscles perform better when they’re warm — hence why we “warm up” before exercise (also to prevent injury).

This leads to a few unanswered questions regarding heat and performance. Can heat training improve on resistance training gains? Few studies have actually looked at this, as most have focused on endurance-type activity.

Second, can short-term heat application potentially improve aerobic exercise performance? If so, this could be a cheap and effective way to run faster or further in a race or workout.

At the 2021 (virtual) Experimental Biology (EB) conference, I attended two poster sessions where researchers investigated these very questions. Below is a short summary of the findings and a few key takeaways.

Poster #1: Long-term concurrent heat stress does not improve upon performance gains by resistance training

For this study, investigators wanted to determine whether resistance training with added heat stress would have an additive effect on performance enhancement — including 1 rep max leg and bench press, 5- and 10-meter sprint time, agility, peak squat jump and ballistic pushup force, and body composition.

18 recreational athletes completed a 10-week full-body resistance training program. One group trained in thermoneutral conditions at 23C (74F) and 25% humidity and another group (the heat stress group) trained in a climate chamber at 40C (104F) and 30% humidity. Pretty toasty.

Results

  • Leg press 1 rep max improved in both conditions
  • Relative strength improved in bench press in both groups
  • Agility improved in the HEAT group at 5 weeks (midway through), but was no different at 10-weeks compared to baseline
  • No improvements were seen in 5/10 meter sprint time or peak force
  • Total upper body and total overall muscle mass increased in both groups
  • Fat mass did not change in either group

Overall — these results demonstrate that concurrent heat stress during resistance training does not seem to have an additive effect on performance or body composition outcomes. Similar gains were seen whether participants trained in thermoneutral or hot conditions.

Poster #2: The Effects of using Deep Heat on Enhancing Aerobic Performance

Investigators in this study wondered whether applying heating cream before exercise could increase endurance capacity and/or prolong time to fatigue. Heating creams (e.g., Icy Hot), while typically used to reduce soreness and pain, have scarcely been used in this context.

9 individuals participated in this study and completed two different trials where they performed a cycling test to exhaustion. During one session, they received a placebo (inactive) cream on their skin and in another session, they received the deep heating cream application prior to exercise.

Results

  • Deep heat cream significantly improved time to exhaustion during cycling (participants cycled for 510 seconds with the deep heat cream and 391 seconds with the placebo).

(Thanks to author G. Balasekaran for granting me permission to use his poster in this newsletter)

This study indicates that deep heat cream application prior to exercise can improve time to exhaustion, and athletes may want to consider using this strategy to achieve optimal endurance performance.

If you’re interested in “heating up” your workout, I would consider trying either of these approaches. Training outside in the blazing summer sun — whether you’re running or pumping iron, could perhaps lead to more significant improvements. As for the acute benefits of heating creams, applying some right before you head to the gym or out for a run could allow you to workout harder or longer.

Heat can be a powerful physiological stimulus, and using it to your advantage could yield some neat benefits.

PhD candidate at the University of Florida — Science writing with a particular focus on exercise and nutrition interventions, aging, health, and disease.