It has been a tough summer for the running crowd. Like an unwelcome relative, hot weather came early and stayed. Not only did the heat arrive, but it was accompanied by high humidity. By now, I expect most runners in the Twin Cities are yearning for the return of slightly cooler and drier weather. I know I am.
If you have noticed a decline in your running performance on hot days, you are not alone. Running in the heat is hard. I was curious to see what researchers have learned about hot weather running performance, so I did a little reading online, and came across an article that provided a very thorough assessment of hot weather running. Here are a few interesting facts from the article.
Distance running performance is optimal at temperatures of 50° to 54° F
The researchers analyzed winning times for a series of marathons that were run at temperatures between 32° F and 75° F. The evidence was quite solid that the elite runners were at the optimal performance level at around 50° F. Increasing temperature to around 75° F slowed the winning times by about 8 minutes. That may not sound like much, but for an elite athlete running a marathon in slightly over 2 hours, it is.
Lighter weight runners do better in the heat
The article noted that during running, about 70-80% of the fuel that the body burns is converted into heat. That is a lot of heat, and it has to be removed from the body, typically by sweating. Lighter runners have less body mass, and generate correspondingly less heat in the process of propelling themselves forward. The reason the elite Kenyan runners are dominating the marathon event is not just about training; they also have the perfect body build for it!
Hydration is very important
When running the hot weather, most people sweat profusely. This is good, as noted above it is the body's method for cooling itself. But all that fluid and salt is coming from somewhere, and that somewhere is inside your body. A failure to replenish both fluid and electrolytes will cause your performance to decline. So stay hydrated.
One strategy I have adopted for the summer months that works well is to do less running and more cycling. Cycling has several advantages: first, it is inherently a more efficient process than running, so you don't burn as much energy when you are cycling. Second, cycling creates a natural flow of air that cools the skin and helps regulate body temperature. I am a member of Twin Cities Bicycling Club (www.biketcbc.org); they have organized ride events most every day of the week, and in all parts of the Metro. Give them a try.
See you in the middle of the pack!
Below is the citation for the article I referenced:
Maughan, R.J.: “Distance running in hot environments: a thermal challenge to the elite runner.” Scandinavian Journal of Medicine and Science in Sports. 2010: 20 (Supplement 3), pages 95-102.