Active Voice: Precooling Strategies and Improvements in Cycling Performance in the Heat
By Megan Ross, B.S.
Viewpoints presented in SMB commentaries reflect opinions of the authors and do not necessarily reflect positions or policies of ACSM.
Megan Ross, B.S., is completing her Ph.D. through Edith Cowan University in Joondalup, Western Australia. Based out of the Australian Institute of Sport (AIS) in Canberra, she travels with an AIS competitive cycling team and conducts performance-related studies with these athletes. Ross is interested in developing strategies for reducing risks of heat injury in cycling competitions. This commentary presents her views associated with the research article she and her colleagues published in the Jan. 2011 Medicine & Science in Sports & Exercise®.
January is the month when cyclists travel “Down Under” to compete in the first event on the UCI Pro Tour calendar – an event held in the extreme heat of the Australian summer. With the stage-race covering ~850 km over six days, in temperatures that often reach over 40°C/104°F, it is important that riders manage their heat stress. As such, research into practical means of cooling, either before, during or after exercise in hot temperatures continues to grow.
Generally, cooling interventions applied directly prior to exercise (or “precooling”) are the most practical and beneficial to performance. Indeed, a wide range of precooling methods, which involve exposure to cool air, cool water and ice, have been shown to reduce deep body and skin temperatures, increase heat storage capacity and improve exercise performance in hot conditions. Although there are logistical limitations that have restricted the use of precooling techniques prior to actual competition, cooling is quickly becoming an important part of cyclists’ pre-event routines at major competitions. With the emergence of more practical choices for precooling – including ice towel application, cold water immersion and ice ingestion – precooling has become more accessible for cyclists to employ in the field. Professional teams now install ice-slurry machines on team buses, travel with portable plunge baths or warm up wearing ice-jackets. This way, sport scientists can individualize cooling strategies with cyclists using various modes, timings and combinations of cooling options for specific event disciplines and the individual roles that cyclists play.
The practice of consuming an ice slurry beverage (14 g.kg-1 BM of a crushed ice beverage made from sports drink consumed 30-60 min before exercise) prior to endurance performance makes practical and logical sense, as it has the potential to not only lower core temperature but also enhance fluid intake. This may be important during exercise in heat, such as in an international cycling time trial in which athletes compete against the clock to secure the fastest time (~50 min, or speeds of ~48 km.h-1) over a set distance (~40 km). A new cooling strategy, which involves the combination of ingesting an ice slurry and applying iced towels, was assessed using a laboratory-based cycling time trial simulating the course characteristics of the Beijing Olympic Games (see Ross et al. 2011). Compared to the control condition where no cooling was used, the treatment strategy achieved the desired reduction in rectal temperature (-0.3°C), which persisted throughout a warm-up. Although pacing during the time trial resulted in similar rectal temperatures, heart rates and ratings of perceived exertion, cycling performance following the combined cooling strategy was associated with a three-percent increase in power output and a 1.3-percent improvement in performance time. Therefore, we believe this strategy represents a practical and effective precooling option for cyclists in preparation for races in hot and humid conditions.
In summary, precooling is now emerging from the laboratory and being used in competitions. With a targeted approach for use within cycling, practical precooling is fast becoming popular among professionals. Reinforced by the benefits of improved safety, perceived comfort and endurance performance, as well as the practical ease of cooling prior to a race, interest in this area of research is mounting. Further research into individualized precooling practices will assist practitioners on how to best prepare cyclists for future events contested in hot conditions.