Remember the old saying “No Pain, no gain?” For most folks, this refers to that burning sensation that comes with a hard workout that usually ends with them dripping with sweat and sore for several days.

As it turns out, the culprit may not be lactic acid as is commonly assumed, but may actually be good, old-fashioned heat. New research has shown that when an athlete is properly cooled through the use of a special cooling glove, muscle fatigue and delayed muscle soreness virtually disappears.

In addition, the cooling effect appears to be so profound that even after a grueling workout, an athlete can be cooled and the workout can be repeated, almost immediately, with almost no performance degradation. Even more intriguing, there is virtually no muscle soreness afterward.

A Stanford University study funded by the Department of Defense (DARPA) found that as core body temperature rises, muscle fatigue sets in as internal muscle temperature approaches 104°F. This is because an enzyme called muscle pyruvate kinase or MPK, begins to change shape as it gets hotter. When it bends, the individual muscle fiber can no longer contract and the muscle begins to fatigue. This seems to be a natural temperature control mechanism that keeps us from cooking ourselves from the inside out under high exertion.

When the muscle is rapidly cooled back to normal, the MPK bends back into its normal shape and the muscle can contract again, effectively resetting it. This allows the athlete to get right back to work as if he were just starting the exercise. In the lab, this leads to incredible gains in stamina–the test subject increased from 180 pull-ups to 620 pull-ups in just six weeks when cooled between sets.

The working hypothesis for this incredible stamina gain could possibly be because the muscle was able to be fully stimulated at every fiber. This is normally not possible since the heat generated from a neighboring fiber contracting hard will spill over into the next fiber and as the ambient temperature rises, fibers that have not yet been activated will already be too hot to properly contract. This leads to complete muscle fatigue and failure while a good portion of the muscle is simply too hot to operate properly–much like an overheated engine will fail long before it runs out of fuel.

Conversely, when the muscle remains cool, it can operate to its full potential, effectively running at full throttle until the local fuel reserve (called glycogen) is fully exhausted and there is simply no more readily available fuel for the muscle to continue. Previous studies have shown that when stressed to glycogen depletion, muscle cells react by significantly increasing their local glycogen storage capacity. In this case, it would appear that in the study period, the storage capacity increased almost three times in six weeks, a feat normally requiring months or years of training.

The lack of delayed muscle soreness is also very interesting. It implies that there is a direct connection between heat and muscle damage, but that the damage is not immediate. It must occur somewhat later after the muscle has stopped working. It would appear that the muscle effectively “cooks” itself over a period of several minutes unless it is rapidly cooled. This could be why continuing to move around after intense workouts leads to less soreness: increased blood flow cools the muscle more effectively while sitting down to rest causes the blood to pool and the heat remains localized.

While it remains to be seen how cooling impacts overall muscle strength and growth, it is clear that any type of endurance sport or exercise can benefit. Imagine a marathon runner or a boxer being cooled between rounds; they could potentially eliminate muscle fatigue as a determining factor in the competition. The marathoner could basically sprint the entire race and boxers would tire less in later rounds. In fact, several professional sports teams are already using it to improve performance in football and hockey.

We could be on the cusp of a new level of endurance sports performance that potentially eliminates the pain of training both during and after a workout.

That’s what I call a win-win.

By Wesley Powell