Handling Conditions with Respect: Summer Heat & Humidity
The first week or two of running in the heat can be fairly brutal. While for most, “adapting” takes about 10 days, it doesn’t mean that the body isn’t still working hard during high temps and humidity. In the South, we refer to humidity as “poor man’s altitude,” and that is because physiologically humidity and altitude involve similar processes of adaptation. While exercising in the heat, your body is actively taking oxygen from your working muscles to cool you down through sweating. When at altitude, you simply start with less oxygen to begin with. Working out in very hot conditions provides us with a number of challenges when it comes to adaptation and performance. One's ease of adaptation depends on a number of different factors such as one's acclimatization state, hydration and overall aerobic fitness. Different sweat rates can also play a role in performance.
So why is working out in the heat so hard?
1) As we already mentioned, the process of external cooling requires actively taking oxygen from working muscles
2) Heat stress reduces one's ability to have maximal metabolic rates during aerobic exercise
3) The average person loses about 1 liter of sweat per hour during exercise in hot conditions. That can be hard to efficiently replenish while running.
4) Continuing from point 3, dehydration from sweat loss decreases blood volume which results in being less efficient at cooling and causing elevated core temperatures
5) Metabolic demands compete with thermoregulatory demands, making it challenging to maintain proper cardiac outputSo what do you do about it?