The Good Thing About Heat.
From the moment that Athens was awarded the 2004 Olympics, sport scientists, coaches, and athletes alike knew that heat, humidity, and even air pollution were going to be major environmental factors that will seriously affect the performance of the athletes. The good thing is that, similar to the 1968 Mexico Games kick-starting scientific and applied sports interest in altitude training that still hasn’t abated, these Olympics have spurred a lot of fundamental and applied research into ways to minimize the potentially debilitating effects of heat.
To get a primer on the effects of heat stress and the benefits of pre-cooling, check out my first-ever contribution to Toolbox here on Pez!
The leaders in this field have tended to be Commonwealth countries (Marino 2002; Noakes 2000; Cheung and Sleivert 2004), partly because we already had the experiences of the 1998 Kuala Lampur Games to draw upon. My research partner Dr. Gordon Sleivert, the Director of Sport Science & Medicine at the Canadian Sport Centre Victoria (home of Alison Sydor, Ryder Hjesdal, and Roland Green, along with triathletes Simon Whitfield and Peter Reid) worked with the New Zealand teams at those games, spurring a lot of the current research we are conducting into the effects of heat stress on performance and the use of cooling jackets.
The Games are already underway, so I can give away the Canadian plan of attack. Besides, Gord’s in Athens and too busy to check up on me anyway! It is unlikely that TV coverage will really show or focus on it, but many of the rowers will be warming up for their events by wearing cooling vests and hoods. These are not simply vests stuffed with ice packs, because it’s very difficult to have a huge supply of ice packs kept frozen and replaced on-site, given the heat and the lack of refrigeration.
The units the rowers will likely be using are often referred to as “tubesuits”, being tight-fitting stretch garment with tubing sewn throughout. This permits the pumping of coolant throughout the garment, providing continuous cooling at a set temperature rather than having the cooling capacity drop off as the ice melts. The cooling will be performed by a unit that keeps the coolant cold and can feed up to ten individuals at a time. That will permit an entire team of eight to warm up on ergometers while keeping cool at the same time, all powered by a big generator! Indeed, one of Gord’s students just did a study with the rowers, and we think it has a lot of potential for individual and team endurance events.
These tubesuits were originally (and still are) used by astronauts underneath their spacesuits. In Canada, we adapted them to work underneath chemical warfare clothing during the 1990/91 Gulf War, and our helicopter pilots were able to fly twice as long as those from other nations. Theses tubesuits are also starting to make an appearance on NASCAR drivers.
Why are we focusing on vests and hoods? The goal is to permit the arms and legs to exercise and get the usual benefits of warming up prior to competition, all the while keeping the torso and brain as cool as possible. This follows research by Gord finding that pre-cooling of the legs eliminated most of the benefits of warming up (Sleivert et al. 2001), and also his student’s finding that head-cooling by itself was beneficial prior to high intensity running (Palmer et al. 2001).
Hitting the Road
How can we apply some of this work to our own cycling performance?
1. Keep as cool as possible prior to your event! Do everything you can to stay out of the sun and heat prior to your event. We have been advising our swimmers to use tubesuits or ice vests while they’re sitting in the stands day after day cheering on other swimmers. Every bit of heat exposure is unnecessary additional stress that detracts from your training or recovery.
2. Keep hydrated and drink the days before and the morning of your event. Nothing has a bigger effect on your performance, as even a 1% decrease in body weight from fluid loss can have significant performance effects. Dehydration becomes a negative spiral in that it further impairs your ability to tolerate heat stress because you have less blood volume to dissipate heat with. If I only had a little bit of water left in my bottle, I would choose to drink it rather than pouring it over my head.
3. You need to cool a good chunk of your body, or else be really smart about it. You may have seen some flexible gel packs shaped like tubes that you can drape around your neck and collar. Nice idea, but the cooling capacity of these styling little collars are far too small to have any real effect. There has also been some new units (trade name RTX) that cool your hand by placing the palm on a cold metal globe and using a slight vacuum to keep the blood vessels open despite the cold. These units carry a lot of potential and the research presented by the designers are intriguing, but the scientific jury is still out on them.
4. Concentrate on cooling the head and torso areas. Quit stuffing those ice packs down your shorts! As noted above, you want to avoid actively cooling your legs. Gord has been known to have his mom sew him some simple Lycra hoods with ice packs sewn inside. These may be the simplest low-tech solution available to most of us, and what I would recommend as the best overall solution in terms of simplicity and location. An added benefit from head cooling is that recent work from South Africa and Australia suggests that an individual may subconsciously select a pace based on psychological (i.e., head) perception of heat stress, with a lower pace with a hotter brain (Cheung and Sleivert 2004; Marino et al. 2004).
OK, so no more excuses about it being too hot to ride outside. Keep reading, keep writing, and keep cool!
A primer on the effects of heat stress and the benefits of pre-cooling
Action for Athens
The first installment in my 2003 series on hydration and fluid replacement
1. Marino FE. Methods, advantages, and limitations of body cooling for exercise performance. British Journal of Sports Medicine 36: 89-94., 2002.
2. Noakes TD. Physiological models to understand exercise fatigue and the adaptations that predict or enhance athletic performance. Scand J Med Sci Sports 10: 123-145, 2000.
3. Cheung SS and Sleivert GG. Multiple triggers for hyperthermic fatigue and exhaustion. Exercise and Sport Sciences Reviews 32: 100-106, 2004.
4. Sleivert GG, Cotter JD, Roberts WS and Febbraio MA. The influence of whole-body vs. torso pre-cooling on physiological strain and performance of high-intensity exercise in the heat. Comparative Biochemistry and Physiology – Part A: Molecular & Integrative Physiology 128: 657-666., 2001.
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 Taylor NA, Wollongong, Australia. Australian Physiological and Pharmacological Society, 2001, p. 122P.
6. Marino FE, Lambert MI and Noakes TD. Superior performance of African runners in warm humid but not in cool environmental conditions. Journal of Applied Physiology 96: 124-130, 2004.
Stephen Cheung is an Associate Professor of Kinesiology at Dalhousie University in Halifax, Nova Scotia, Canada, and has been flash-frozen or boiled more often than he can remember. Stephen’s company, Podium Performance, also provides elite sport science and training support to provincial and national-level athletes in a number of sports. He can be reached for comments or coaching inquiries at email@example.com.