Training: Pre-Cooling In The Heat
– By Stephen S. Cheung, Ph.D. –
Associate Professor, Dalhousie University
Spain is known for a couple of things during September and La Vuelta: baking hot weather and racing that is muy caliente. I remember a summer spent in Barcelona where my laundry got wetter instead of drier while hanging out on the line, and my leaving for bike rides at 6:30 am so that I could get home before the stifling heat got too bad.
We have all been drilled in the importance of taking care during training and racing in hot weather to drink enough and to prevent overheating. Research done in my lab has demonstrated that improper hydration before and during exercise in the heat will negate any advantages earned through increased physical fitness or a program of heat acclimation (2). That same research also suggested the existence of a critical internal temperature at which the body cannot voluntarily sustain further exercise.
This has coincided with a renewed interest in the possible ergogenic benefits of pre-cooling the athlete prior to exercise in the heat, with some Australian Olympic rowers taking to wearing vests with ice packs during warm-ups to maximize the muscular benefits of warming up while minimizing the amount of heat stored in the body. The theory is simple. If you can cool your body down a little bit before exercise, then your body can store more heat before it reaches a critical point of hyperthermia, and you will therefore be able to exercise harder and/or longer (4).
The scientific research that has been performed on pre-cooling has largely supported its ergogenic benefits. Pre-cooling by 0.4oC resulted in decreased heart rate and heat storage during subsequent running in the heat (3). In addition, following pre-cooling by 0.5oC, the maximum distance ran by trained runners during a 30 min time trial increased by 300 m (1). Another recent study found that simply pre-cooling the head was sufficient to improve comfort and performance during running in the heat (5).
Before you sit shivering in a cold shower for an hour before your next race in the heat, keep a few caveats in mind. The bulk of the research has focused on steady and prolonged (~30 min) TT-like efforts, and the jury is still out on whether short events or sprinting, crit or RR-type efforts would benefit from pre-cooling. Shivering and getting cold is also no fun, and the practicality of actually achieving pre-cooling comfortably and efficiently at athletic venues, while still maximizing a proper warmup, remains a major impediment to its widespread use.
Stephen Cheung is an Associate Professor of Kinesiology at Dalhousie University in Halifax, Nova Scotia, Canada, with a research specialty in the effects of thermal stress on human physiology and performance. He has been an avid roadie since beginning university in the mid-eighties, and still has non-indexed downtube shifters on his winter bike and wool jerseys hanging in his closet. He currently races Cat. 3/Vets with the Bicycles Plus cycling team. Stephen is also the President of Podium Performance Inc., a company specializing in training consultations and sport science support to elite athletes in many sports. He can be reached for advice or comments at [email protected]
1. Booth J, Marino F, and Ward JJ. Improved running performance in hot humid conditions following whole body precooling. Med. Sci. Sports Exerc. 29: 943-949, 1997.
2. Cheung SS, and McLellan TM. Influence of heat acclimation, aerobic fitness, and hydration effects on tolerance during uncompensable heat stress. J. Appl. Physiol. 84: 1731-1739, 1998.
3. Lee DT, and Haymes EM. Exercise duration and thermoregulatory responses after whole body precooling. J. Appl. Physiol. 79: 1971-1976, 1995.
4. Marino FE. Methods, advantages, and limitations of body cooling for exercise performance. Br J Sports Med 36: 89-94., 2002.
5. Palmer CD, Sleivert GG, and Cotter JD. The effects of head and neck cooling on thermoregulation, pace selection, and performance. International Thermal Physiology Symposium, edited by N. A. Taylor, Wollongong, Australia. Australian Physiological and Pharmacological Society, 2001, p. 122P.