I’ve enjoyed returning to 95-100F temperatures after spending much of the summer in below 70F, dressed in fleece, and riding with arm warmers. It’s important to manage core temperature on the bike these first couple of weeks while acclimating and to minimize risk of heat illness – you know the symptoms – muscle cramps, headache, faint or dizzy feeling, nausea, decreased ability to coordinate movements, hyperthermia, and general fatigue. Plus exercising vigorously in hot (90F plus) and/or humid environments can decrease performance significantly. Generally heat acclimatization takes about 7-14 days.
Here’s what happens – As you begin to exercise, the body produces extreme amounts of heat. To cool the core temperature blood flow is redirected to the skin and heat is released by sweating, reducing blood flow back to the heart. This results in a decreased cardiac output which increases heart rate to compensate for the reduced blood volume to maintain the workload. Increased sweat rate also leads to dehydration and loss of electrolytes.
The acclimatization plan – progressive moderate exercise, adequate hydration with electrolyte replacement. Here’s a great article on heat acclimatization