You hot racer, you
“A rise in core temperature can alter brain chemistry and impair cognitive function, and also change gut bloodflow”
Stephen Cheung runs a research lab investigating the effects of environmental stress on cycling performance and had some interesting insights into heat.
“Fatigue and discomfort in the heat isn’t just down to one factor,” Cheung revealed. “Core temperature plays a key role, especially its impact on a variety of systems. As a snapshot, this rise in temperature alters brain chemistry and impairs cognitive function; it changes gut bloodflow, causing leakage into the system… It’s not simply a case of core temperature rises and you ‘feel’ uncomfortable.”
This discomfort can develop into something more serious like heatstroke. That’s where, Cheung said, acclimatisation comes in. This is where the body is exposed to, in this case, artificial heat for a period of time to stimulate physiological changes that are conducive to riding in the heat. “These include more efficient sweat response, expanded volume to allow the blood vessels to pump more blood to the muscles and better ability to control body temperature,” said Cheung, who categorises the acclimatisation period into: short-term (fewer than seven days); medium-term (eight to 14 days); and longterm (over 14 days). “They all produce favourable results but, not surprisingly, the longer the better.”
A study by Danish researchers supports Cheung’s work. The team took trained Danish time-triallists and had them ride 43km at 300 Watts in 5°C. They then headed to a training camp where temperature ranged from 30–36°C. They rode further 43km time-trials on day one, six and 13 of the 14-day camp. “On day one, they were about 85% of their performance level,” Cheung explained. “By day six, that had risen to 92%. By day 13, it’d risen to 95%. This shows acclimatisation works.”
This acclimatisation can take place at your local university if it has an environmental chamber. This is, however, expensive, impractical and unrealistic for most of us. Instead stick your turbo trainer in a small room, add a fan heater, crank up the radiator and get pedalling. Just make sure you have a bottle of water to hand. An hour in this sweat box is enough.
“Another option is to have a hot bath straight after riding in normal conditions,” added Cheung. “There’s research that shows this has a small adaption benefit.” Professor Neil Walsh of Bangor University showed that moderate exercise immediately followed by a 15min bath in 40°C waters over six days where bath-time rose by 5mins each day resulted in a 4% improvement in 5km time-trial time in the heat. The explanation for the benefits likely involve the combined elevation of core body and skin temperatures.