Victor asks: I like to run at lunchtime during the summer. My friend told me that running in the heat increases your red blood cells, and that this is akin to blood doping, and as a result my PRs don't count. I know he's joking about doping, but wanted to know how running in the heat impacts blood cells.
Yes, your PRs do count. Heat acclimatization is quite different than blood doping. Blood doping is withdrawing your own blood and giving it back to yourself before a race to increase red blood cell mass. It is not legal in the sports world.
But running at noon in the heat of the day will induce heat acclimatization, a natural response to training. Running in the heat stimulates your body to produce more oxygen-rich red blood cells. And that will improve your ability to perform well in warm or hot conditions. That is, of course, the purpose of training—and is legal.
If you plan to race in hot conditions, it is critical to have near daily heat exposure while you are training to get your body ready to perform in hot conditions. If you feel it is too hot for you when you arrive at the race site, it may be best not to start or to start at a slow pace and drop out if you do not feel well during the run. It is always better to not start, not finish, or finish slow than to end up in the medical tent or emergency department with exertional heat stroke.
I hope this helps.
