Toolbox: Every rider has their own weather kryptonite. It’s a condition that turns a good ride into a fest of suffering. But beyond personal preference, the fact is ideal temperature For performance? And does your body react differently when it’s cold than when it’s hot? Today’s Toolbox examines the science of environmental temperature and endurance, how the environment affects performance, and why men and women don’t react the same way when the mercury rises or falls.
~ We all tend to have a temperature that is suitable for cycling, but is there a physiologically optimal temperature for exercise, and are there any differences between men and women?
Snow, rain, cold wind, gray skies… no!
When it comes to cycling, we all have a weather condition called kryptonite. That set of conditions makes cycling feel downright terrifying. For me, kryptonite is days of 2-4 degrees Celsius, gray skies with no sun to warm me, and cold winds that blow through me no matter how well I dress. In fact, I like riding on sunny but sub-zero days.
Much of this liking and disliking stems from personal experience and cultural background. But is there also a physiological component? Does physical performance change depending on temperature?
Click on the video below!
References
Sunsand M et al. Effect of ambient temperature on endurance performance when wearing cross-country ski clothing. Eur J Appl Physiol. 112(12):3939-3947, 2012.
Lemberg J et al. Effect of ambient temperature on female endurance performance. J Thermal Biol. 45:9-14, 2014.
transcript
Like the baby bear in the fairy tale “The Three Bears,” we generally prefer to keep things at a comfortable temperature. That’s also true for many of us who have a preferred temperature at which we exercise. But does our physiology and actual performance work best at certain ambient temperatures?
In today’s episode, we introduce two studies that tested men and women exercising at different temperatures. Is there an optimal temperature for exercise? Is that temperature similar for men and women?
Our bodies are optimized to function within a very narrow internal temperature range, and our physiological and behavioral thermoregulatory systems have evolved to keep ourselves within this narrow temperature range, whether we are at rest or exercising, in the tropics or the arctic. Of course, shivering when it’s cold or sweating when it’s hot uses additional energy. This naturally raises the question: Is there an optimal ambient temperature for exercise? Research conducted since the mid-1990s suggests that around 10°C is ideal, and performance begins to decline as it gets hotter or colder. However, since all of these studies were conducted on men, it is also an interesting question whether there are gender differences, as women respond differently to heat stress.
Two Norwegian studies in 2012 and 2014 investigated both of these questions, using the same methodology, one with nine well-trained male endurance athletes in cross-country skiing or orienteering, and the other with nine well-trained female endurance athletes in the same sport. Tests were conducted at six temperatures ranging from 20°C to -14°C. Testing included running on a treadmill at a warm-up pace, running at four different speeds to test running economy and lactate threshold, then running at a vigorous pace until exhaustion to test maximum aerobic capacity and exercise tolerance. I wore standard cross-country ski racing clothing, with extra gloves and a neck warmer for frigid conditions to prevent falling off due to discomfort. Women were tested during the luteal phase of their menstrual cycle.
First, let’s take a look at the 2012 survey of men. The graph shows the allowable time in seconds for each of the six temperature conditions. A general inverted-U pattern is observed, with best performance at 1 °C and -4 °C, but performance gradually declines as temperatures get cooler or warmer. A similar peak in running speed at a -4 lactate threshold was also seen, but running economy generally worsened with higher temperatures. However, no difference was observed in VO2max. The inverted-U pattern in performance as a function of temperature supports similar studies in men, although the optimal temperature here is lower than in other studies. But what’s really interesting is that the 2014 women’s study found no absolute differences in any of the measurements, despite using the same methodology and targeting similarly healthy athletes in the same sport.
This study was unique in that it validated known observations in men to see if it also applied to women. The authors were quite puzzled as to why men’s performance was affected by ambient temperature while women’s performance was seemingly unaffected. In the heat, although women generally had lower sweat rates, evaporation was more efficient and therefore may not have been as affected by dehydration as men. When it was cold, women had lower skin temperatures and more body fat for insulation, so they may have lost less heat than men. Either way, this study once again emphasizes that women are not little men, and that there is an urgent need to study their unique physiology in environmental physiology and health research.
Train in warm weather
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