Running Doc: Are Women More Suited For Endurance Than Men?

The Running Doc explains why women might be better equipped for endurance events.

The Running Doc explains why women might be better equipped for endurance events.

Written by: Lewis G. Maharam

It sounds ludicrous now, but the running boom of the 1970s advanced quite a bit before women were even allowed to participate in many marathons. That’s even more surprising in light of the latest scientific speculation about women’s considerable endurance. Women, it now seems, might have been better equipped all along than men! At least that may be true as far as fuel is concerned when female endurance reserves are compared to those of the stronger men who were protecting the “weaker sex” as too delicate for such a grueling distance.

Whatever advantage women may possess probably doesn’t kick in until a running event gets at least as long as the marathon—anything 26.2 miles or over, or its equivalent in another sport. And if our theories are correct, the longer the event is, the greater the possible advantage is.

Tracy Sundlun is a senior vice president of Competitor Group, which puts on the Rock ’n’ Roll series of marathons and half marathons, among other events, and he is also an Olympic track coach who has trained over 30 Olympic Trials Marathon qualifiers. In Sundlun’s view, “The differences as you probe farther into the ultradistances seem to indicate men and women are competing more on an even plane.” Women are, indeed, beating men at ultradistances!

It may be a simple matter of fat stores—the increased body fat so many women athletes resent in themselves as some kind of deadweight, wishing it were muscle instead. We know that after about 18 miles of steady running, the body begins to get low on glycogen— hitting the famous “wall”—and turns increasingly to other energy stores to keep going. But only recently, thanks in part to increasing numbers of women ultra-athletes and the times they’re turning in, have we begun to suspect women may be more efficient at using that body fat early in a race and saving the glycogen for the long haul. A bigger tank and a more efficient fuel injection system? That could be.

Until now we’ve had only two major studies on the subject, and they conflict. But a recent one suggested that women may in fact have some way, not yet understood, of preferentially burning fatty acids better than men do. If that’s the case, and we factor in that ability with women’s greater body fat reserves, the implications are obvious. Assuming there is some glycogen sparing going on along  the way, women might be able to get more out of that premium fuel than men do.

Larger fuel tanks aside, women ultra-athletes may also have additional chemical advantages that are not only perfectly legal but also perfectly natural. The more we find out about the powerful hormone estrogen, the more athlete-friendly it seems. For one thing, estrogen is a formidable antioxidant. And whatever your position on Dr. Kenneth H. Cooper’s Antioxidant Revolution, a book that contends that exercise releases cancer-inducing free radicals and that ultraathletes could be most at risk, it’s highly probable that antioxidants help protect us from some pretty malignant conditions, whether we run over 60 miles a week (Cooper’s “ultra” cutoff ) or not. And though clean arteries don’t help us run faster or longer, women athletes can be grateful that estrogen is also an antilipid agent, meaning it helps fight atherosclerosis, more commonly known as hardening and clogging of the arteries.

Even bottomless energy reserves wouldn’t do much good for the athlete who is too pooped to access them, however. Muscles get tired as they run out of fuel, but the brain also has a mechanism by which it tells our body that we are weary. And if some recent studies are correct, estrogen attaches to a neurotransmitter in the brain, and the combination may delay the fatigue message. The result: The body doesn’t feel as tired, so it doesn’t race as tired.

Should all this prove true, does it mean women will ultimately own the longer distances? You’d be hard-pressed to find anyone who’d say so. “Do I believe that women marathoners will ultimately run as fast as men? I absolutely do not,” declares Sundlun. But the fact that women are still relatively new to all this endurance work provides some pretty interesting headroom.

“Will women’s marks continue to drop more precipitously than men’s for a while? Absolutely,” Sundlun adds. “And I think the evidence will prove that percentage-wise, the difference between the records in the ultra areas should ultimately be closer [between men and women] than at those events where power and muscle mass are  more involved. It does look like women have some genetic qualities that would make them more efficient in those areas.”

So, a word of warning to marathoning men: Even postmenopausal women have more estrogen than you do! Remember that the next time you’re planning a really long workout and wonder whom to ask along to make you look good. Your female running friend may be slower, but she’s probably a bundle of potential energy. When it’s all over, you might be surprised to find that the “weaker sex” is you.

This article was adapted from the new book Running Doc’s Guide to Healthy Running with permission of VeloPress. From head to toenails, Running Doc’s book explains healthy running practices and guides runners to the right diagnosis and treatment for over 100 running injuries and related health problems. Running Doc’s Guide to Healthy Running is now available in bookstores, running shops, and online. Download a free sample and preview the contents at