Before girls and boys hit puberty, their bodies are fairly similar. During puberty, however, boys experience a surge of testosterone. By adulthood, some men have up to 20 times more testosterone than women do, according to HealthLine.
Testosterone plays several roles, including telling the body to create new blood cells, keeping bones and muscles strong and prompting growth spurts, according to the Society of Endocrinology.
“Because [women] produce less testosterone, we are at a disadvantage in terms of muscle,” said Dr. Emily Kraus, a primary care sports medicine physician at Stanford Health Care in California. “Males have a greater amount of muscle bulk.”
A man’s leg is about 80 percent muscle, compared with about 60 percent muscle in a woman’s leg, Kraus said. That extra muscle can help men run faster, she said. Also, men’s muscles tend to have larger fast-twitch muscle fibers, which help with sprinting, than women do, Kraus said.
In addition, women have more estrogen than men do, which leads them to have a higher percentage of body fat than men have. “That can also lead to a small disadvantage for running performance [for women, in comparison with men],” Kraus said.
Body size is another factor. Women, on average, have smaller lungs than men do, meaning their maximal oxygen consumption (VO2 max) is lower. The VO2 max for a sedentary woman is about 33 milliliters of oxygen per kilogram of body mass per minute, while a young sedentary man’s is about 42 ml/kg/min, according to a 1998 study in the journal Medicine and Science in Sports and Exercise.
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Women’s hearts also tend to be smaller than men’s, which means they have a smaller stroke volume, or the amount of oxygenated blood that the left ventricle pumps out in one beat.
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To top that off, women also have less hemoglobin, the protein in red blood cells that carries oxygen to the body’s tissues, including the muscles, Kraus said.
As far as biomechanics, men usually have longer legs than women do, meaning they have more room for muscle, as well as a longer stride length, said Dr. Miho Tanaka, an assistant professor of orthopedic surgery and director of the Women’s Sports Medicine Program at Johns Hopkins Medicine.
Moreover, because women tend to have wider hips, their running stance is not as efficient as a man’s is, Tanaka said.
So in other words, it’s a fool’s errand to deny that God makes men and women differently and for different purposes, and to insist that women be integrated into infantry because “they can do everything a man can?”
