July 27th, 2010
Working out in the 100 degree weather while on vacation was amazing! However, I noticed a few things; 1) how fatiguing it was, 2) I felt my calves and quads cramping up during my long hikes and 3) man do I sweat (to the point that I could ring out my clothes). None of this was a surprise to me. After all, everyone knows to drink water in the hot weather to prevent dehydration and to replenish fluids and electrolytes to prevent cramping. But I want to know when and why so I decided to do a little research.
We all know that we sweat to cool off. Sweating is our body’s response to a rise in core temperature. However, through sweating we lose water and electrolytes. In my research I stumbled across a few studies. One study showed that in temperate conditions, dehydration (4 percent body weight loss) reduced single-leg knee endurance time by 18 percent compared with euhydration. FN1. Another study showed that increased body temperature is the main factor underlying the early fatigue with dehydration during prolonged exercise in the heat. FN2. Finally, I found it interesting article which noted research suggesting the effects of dehydration on performance are much greater when training in higher temperatures than training in cooler temperatures. Thus, I can be just as dehydrated but cooler and my performance will not be as affected. FN3.
By the end of my research my head was spinning with scientific and medical jargon which seemed to leave me with more questions than answers. But the one thing I am sure of is major jumps in heat will affect my training.
As I continued reading, I noted that many sources found adaption to the heat occurs within 7-14 days. I don’t know about you, but this makes complete sense to me. Doesn’t the first super hot day seem to be the most difficult training day? Then as the heat persists, we acclimate. Thus, seasonal changes in temperature are less likely to have a big impact on our training. However, traveling for a game/race/event or a huge spike in temperature on game/race/event day is going to be much more detrimental.
If you are planning an event at a location that will be hotter than your normal training temperature, you can plan accordingly. One option is to get to the event location a week early. As I write this, I know that is a luxury non-professional athletes don’t have. Similarly, you may prepare for an event and the day comes and the temperature is 15 degrees higher than what you are used to. In these times, hydration, hydration, hydration is key.
In the end, we really don’t have total control over our event day environment, but we can be prepared. Next surprisingly hot day, get out there and get your training done. Make sure you are prepared i.e. extra water, sodium, gel, whatever you take. Keep a journal of how the heat made you feel during your workout and after your workout. Allow yourself time to recover. If you are hit on an event day, don’t assume you can push through it. The last thing you want is to cramp up or pass out because you didn’t pack extra sodium pill/water/Gatorade.
FN1 Michael N. Sawka, Ph.D., Scott . Montain, and William A. Latzka , ‘Fluid and Electrolyte Supplementation for Exercise-Heat Stress’, http://are.berkeley.edu/heat/Fluid.html
FN2 ález-Alonso J, Calbet JA, Nielsen B.. ‘Metabolic and thermodynamic responses to dehydration-induced reductions in muscle blood flow in exercising humans..’ J Physiol. 1999 Oct 15;520 Pt 2:577-89.
FN3 Maughan, Ron and Shirreffs, Susan(2004) ‘Exercise in the heat: challenges and opportunities’, Journal of Sports Sciences, 22: 10, 917 — 927
You’re so right about the getting used to it part. If one of my objectives is to sweat, and I’m hydrated well-enough, and pick an appropriate time of day, exercising in Atlanta summer is doable. That being said, I pretty much never get used to the heat when trying NOT to sweat, much less when trying to look nice. In the non-exercising scenario, it just never feels okay. LOL
Heather, I am SO with you. If I am trying to look decent….ewwwww ~ I can’t stand the heat. I made a decision this vaca to just be sweaty! I think I showered twice a day, knowing I was going to sweat again.