Sunday, August 12, 2007

Preparing for Exercise in a Hot Environment

by Coach Tammy Metzger, B.Sc.

Since I’m heading off to do the Hotter ‘N Hell Hundred ride in Texas at the end of this month, I hit the research to get some ideas on how to get my Pacific-NW body ready to perform in temperatures above 75F. As with most things in life, I feel a big part of it is mental; accepting the heat instead of thinking about how cool it may be at home. I spent a few days in New Orleans back in the summer of ‘05, and I was miserable until I accepted the fact that my clothes were going to stick to me, my body would feel like it was covered in slime, and there was nothing I could do to change that. Once I embraced that reality, I was much more content. So, accept the heat… embrace it even…. What else?

We know that carbohydrate utilization increases in hot environments, so a modified carbohydrate-loading protocol, along with establishing an early and consistent fueling strategy will be integral to success. This will also help to keep up with the increased fluid needs, which are much more likely to be the limiting factor while exercising in temperatures close to or in excess of 100F.

In the December edition of the Cycle U News I published an article on glycerol-loading. At that time, I was unaware of research published by Dr. Lawrence Armstrong back in February 2006, but the findings from his lab back up my original conclusions. Dr. Armstrong’s work on hydration at the Human Performance Lab at The University of Connecticut is very highly regarded. His lab has found a greater plasma volume during exercise, as well as improved exercise capacity in heat (37C / 99F) after rehydration with glycerol (1 g/kg BW) in addition to water (1). Possible side-effects of glycerol-loading include a “heavy feeling” due to increased water storage, and gastro-intestinal distress. As with all things, test your individual response prior to event day.

Another important consideration is keeping the stomach actively emptying (gastric emptying) to assure fluids and fuel are getting to the intestine for absorption. Creating gastric distention can initiate the gastric emptying response early, thereby improving the chances of keeping it going. Immediately before your event starts, ingest 5 mL/kg BW of water or sports drink (2). Follow up with a high-frequency of fueling in smaller amounts.

Luckily, staying hydrated will not necessitate the elimination of my morning java. Once again we turn to the Human Performance Lab at UConn for research that indicates caffeine intake has no effect on thermoregulatory responses to exercise in the heat (3). Do you think I can safely check my French press for air travel? Hmm… maybe not.

And the final consideration in this Hotter ‘N Hell adventure is protection from the sun. Keeping a fair-skinned individual such as myself from burning to a crisp during a century ride under the scorching Texas sun necessitates a little foresight. For guidance in this area, I turn to recommendations from Gordo Byrn. Gordo’s numerous Ironman competitions, not to mention Ultraman Championship, have given him a little insight in this area, which he graciously shares with the rest of the endurance sports community (4). He recommends using water-based sunscreen, and to begin application the night before your event, and again in the morning. Of course, the HHH is not a ‘race’ for me, so I will be doing mid-ride applications as well, and hopefully the base of color I have acquired in recent weeks will help protect me from too much damage.

Stay cool out there, and wish me luck!
Coach Tammy


1. Kavouras SA, Armstong LE, Maresh CM, Casa DJ, Herrera-Soto JA, Scheet TP, Stoppani J, Mack GW, Kraemer WJ. Rehydration with glycerol: endocrine, cardiovascular, and thermoregulatory responses during exercise in the heat. Journal of Applied Physiology. 2006; 100(2):442-50.
2. Burke L & Deakin V. Clinical Sports Nutrition (3rd ed.). Australia: McGraw-Hill. 2006; 374.
3. Roti MW, Casa DJ, Pumerantz AC, Watson G, Judelson DA, Dias JC, Ruffin K, Armstrong LE. Thermoregulatory responses to exercise in the heat: chronic caffeine intake has no effect. 2006;77(2):124-9.
4. Byrn, Gordo. G-tips. Online database. http://www.coachgordo.com/gtips/index.html