It comes down to differences in how our bodies process oxygen.
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Sports, from Little League to the Olympics, are typically segregated by sex. Due to advantages in size, strength, and speed, men are generally considered to be superior athletes. But in one measure of fitness, they’re actually at a disadvantage: According to a recent study in the journal Applied Physiology, Nutrition, and Metabolism, women process oxygen faster than men.
Researchers at the University of Waterloo in Canada asked nine men and nine women of equal fitness levels to start walking on treadmills. As they transitioned from standing to walking, the researchers measured the amount of oxygen the men and women used in each breath, and how long it took them to adapt to the activity. “This tells you how efficient the aerobic system is,” says Richard Hughson, a professor of kinesiology at Waterloo and coauthor of the study. They found that the women, on average, took just 30 seconds to adjust to the walking, while men took 42 seconds.
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“If you don’t use aerobic sources of energy, you have to use anaerobic sources,” Hughson says. Women are able to use oxygen to power their muscles more quickly, meaning they’re relying less on anaerobic energy that produces lactic acid. With less lactic acid in their bloodstream, women feel less muscle soreness and don’t have to breathe as hard, so their perceived effort is lower than men’s. “Eventually, the men can sort of catch up to the women,” he says, adding that it usually take about 10 minutes of walking.
Hughson also notes that this study only looked at “recreationally active people,” not elite athletes or couch potatoes. He expects that the results would be consistent across the spectrum, and his team plans to examine elite athletes next. This study also only asked subjects to walk on a treadmill. When it comes to running events like marathons, he says, “other factors come into play.”
Men, of course, still tend to be stronger, with more muscle mass and larger hearts than women, but they can’t claim a monopoly on all measures of fitness.
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