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With winter upon us, it is a good reminder that cold weather is not an excuse for inactivity. Athletes from cold-weather climates, such as the Nordic countries, are not content to stay indoors during winter. In fact, cross-country skiers from these colder climates might be considered the premier human aerobic athletes.

Although some picture cross-country skiing as slowly shuffling along at a leisurely pace, the reality of competition is much different. For example, the winner of the 50 km (31 miles) freestyle at the 2014 Winter Olympics finished the race in less than one hour and 47 minutes. That’s longer than a marathon but finished in less time. And these races typically go uphill for 50 percent of the time!

Physiologically, skiing is interesting from many perspectives. The biomechanics of skiing are interesting because the arm and leg movements must be coordinated to efficiently move forward. The whole-body nature of skiing makes the physiology fascinating to study. Cross-country skiing puts large demands on the heart to deliver blood and oxygen to exercising muscle. This challenge is greater than for running or cycling (which engages only the legs) because both the arms and the legs need to work with skiing.

The amount of blood going to the arms versus the legs constantly changes, too. These changes are based on the hundreds of technique transitions needed to cross the varying terrain during a race. The great physical endurance required improves the ability of cross-country skiers’ muscles to use oxygen. These athletes have some of the highest levels of oxygen consumption (VO2max) on record. Legendary physiologist Bengt Saltin and other researchers have used the unique whole-body nature of cross-country skiing to study blood flow delivery. This approach has provided us great insight into the regulation of blood flow in both athletes and non-athletes.

Cross-country skiers demonstrate that cold weather is not an excuse to be sedentary, but rather an excuse to be great.

 Benjamin Miller, PhD, is an associate professor in the department of Health and Exercise Science at Colorado State University. He co-directs the Translational Research in Aging and Chronic Disease (TRACD) Laboratory with Karyn Hamilton, PhD.