Even here in Canada, eventually hot summer weather will come. One strategy popular with athletes for reducing heat stress before or during competitions are ice vests. How effective are they?
For endurance sports, the evidence is clear and unequivocal that performance is impaired with higher ambient temperatures. It’s also reduced in cold temperatures or with a drop in core temperature. Data generally points to an “inverted-U” relationship, where performance is optimal at a moderate temperature, but becomes progressively reduced above or below this optimal range.
This optimal temperature might be lower than we think, with a classic study from my post-doc lab at U Aberdeen finding that cycling tolerance time at a constant hard effort was longest at 11°C, similarly reduced at 4 and 21°C, and further reduced at 31°C . So even what we consider as room temperature, such as when we ride on a trainer indoors, already generates significant heat stress.
There are numerous countermeasures, with the best option a thorough program of heat adaptation over the course of 1-2 weeks of gradual exercise-heat exposure. On the day of, there’s the possibility of pre-cooling with a pre-ride cool/cold bath; an ice vest or cold wet towels over the neck and torso; or drinking cold fluids or ice slurries. Ice vests have been commonly used by elite athletes since the Australian Rowing Team pioneered their use while warming up at the 1996 Atlanta Olympics. The theory is to get the muscular and metabolic benefits of a warmup, but keep core temperature […]