After a long, hard ride, what sounds better — a hot shower or submerging yourself in a bath tub full of ice? While many pro athletes have taken to doing the latter, a study published by The Journal of Physiology concluded that heat is better for muscle recovery.
The study, published Oct 4 2017, looked at whether intramuscular temperature affects recovery following endurance-exercise-induced fatigue.
The study found that recovery — measured in mean power output — was better when muscles were warmed to about 38C than when they were cooled to 15C.
The study was done on humans and mice.
On humans, the exercise was an hour of 'moderate-intensity' arm cycling, followed by two hours of recovery. The study was divided into three groups for recovery, with subjects having their muscled cooled, heated or just left alone, all for two hours. Then the subjects did three 5min sessions of "all-out" arm cycling, all at the same neutral temperature.
"Power output during the all-out exercise was better maintained when muscles were heated during recovery, whereas cooling had the opposite effect," the study reported.
On mice, muscles were given 12 minutes of glycogen-depleting stimulation, then broken into the three temperature recovery groups and tested again. The study found that recovery and fatigue resistance were "impaired by cooling and improved by heating". The study also found that glycogen resynthesis was faster when heated than when at a neutral temperature.
"We conclude that recovery from exhaustive endurance exercise is accelerated by raising and slowed by lowering muscle temperature," the study's abstract read.
Context for cycling
Like any single study, this one should be taken in context. Cold and heat can be used in many ways, of course, so it's all about your end goal.
APEX Coaching founder Neal Henderson has worked for years with pro riders such as Rohan Dennis. He uses heat for acclimatization and cooling to help with core temperature after workouts, among other things.
"From a practical applied sport science side of things, when we have athletes preparing for competition in hot environments and we don’t have hot training conditions – like right now, I’ve got a few athletes preparing to race in Mexico and the Bahamas — then we use exposure to heat," Henderson said, adding that they use a hot tub for a few minutes followed by 10-20min in a sauna after training.
"We also use cooling/ice baths more often when training in hot environments and have multiple training sessions in one day — trying to get core temperature down quickly, so there’s better recovery between same-day workouts," Henderson said. "We also recommend use of ice baths more in the evening as a way of dropping core temperature prior to sleeping, which tends to lead to better quality sleep."
"From the applied perspective, getting quality sleep likely outweighs any small positive or negative short-term physiological responses," he said. "There’s a fair bit of literature regarding the impact of ice baths on sleep quality. This becomes especially important when we have athletes who are in a warm/hot environment without air conditioning or with hot sleeping conditions. Getting the core temperature down with an ice bath/cool water bath prior to sleep is a high priority."