What does it mean to "run like a girl"?
"It means run fast as you can," a feisty little tyke asserts in a Super Bowl ad for Always's #LikeAGirl campaign.
If you ask a biomechanist the same question, you're likely to hear about "Q angles" and transverse-plane hip mechanics.
Men and women have anatomical differences in the structure of their hips and legs, resulting in subtle differences in their running strides. The question that researchers are now tackling is whether these differences mean that the best way to prevent and treat certain common running injuries does, in fact, depend on whether you run like a boy or a girl.
For decades, conventional wisdom has been that women are at higher risk of knee problems because of their Q (for quadriceps) angles. Since women have, on average, wider hips relative to the length of their upper legs than men, their upper legs angle more steeply inward toward the knee, rather than running vertically from hip to knee. This means the quadriceps muscles tug on the kneecap from the side, applying additional pressure and interfering with kneecap movement.
At the Canadian Academy of Sport and Exercise Medicine's annual meeting earlier this year, Maha Elashi, a graduate student in the University of British Columbia's Environmental Physiology Lab, presented preliminary results from a study designed to test this assumption.
Looking back at more than two decades of running injury records from UBC's Allan McGavin Sports Medicine Centre, Elashi noted that women indeed seemed to more frequently suffer patellofemoral pain syndrome (better known as runner's knee), as well as pelvic instability and stress fractures, while men were likely to suffer injuries to tendon and knee cartilage.
But this kind of retrospective analysis can't provide the final word on whether women are at higher risk of injury, Elashi points out. There is no way of knowing whether the men and women who wound up at the clinic over the years were doing similar training, for example.
So Elashi launched a prospective trial, recruiting 68 men and 86 women to participate in a 12-week, four-times-a-week training program leading up to a 10-kilometre race. Under these controlled conditions, her initial results found no difference in the injury rates between sexes. She's now performing further analysis of the data to see whether any of the other baseline measurements she took – Q angle, body mass index, age, balance, hip strength, running history and so on – do a better job of predicting who gets injured.
Another approach is to look more closely at the differences between healthy and injured runners, to see if any sex-related patterns emerge. That's the approach that Dr. Reed Ferber, director of the University of Calgary's Running Injury Clinic, has taken in a series of recent studies.
In a study published earlier this year in the Scandinavian Journal of Medicine & Science in Sports, Ferber and his colleagues used eight high-speed cameras to perform three-dimensional gait analyses of 48 healthy runners and 48 runners suffering from iliotibial band syndrome, a common running injury affecting the band of tissue running along the outside of the leg from hip to knee.
Comparing within each sex, the injured female runners displayed greater hip rotation than healthy female runners. The same pattern didn't show up in men, though; instead, injured male runners had greater ankle rotation than healthy males. So while the end result is the same, "females develop this injury from a hip-down perspective while men develop it from a foot-up perspective," Ferber says.
A similar analysis of data from a multicentre trial on patellofemoral pain found that injured women had weaker hips than healthy women, while injured men had weaker knee extensors (muscles like the quadriceps that enable you to straighten your knee) than healthy men.
"What this means is that if a runner is injured, they should be receiving a sex-specific analysis to determine the root cause of their injury," Ferber says. "The traditional notion of a 'one-size-fits-all' approach to injury assessment and rehab protocols can no longer be followed."
At Ferber's clinic, as well as a dozen other clinics across the country that have adopted his three-dimensional gait-analysis system, this idea is implemented by comparing runners with a sex-specific database rather than using all runners in the system to identify potential abnormalities in their running motion.
Ultimately, as Elashi's findings hint, men's and women's running injuries likely have far more similarities than differences. In study after study, "training errors" – doing too much, too soon – have been fingered as the primary underlying cause of injury, so patience is your best protection. Still, if that fails, it may be worth considering whether you run like a girl or a boy.
Alex Hutchinson blogs about exercise research at sweatscience.runnersworld.com. His latest book is Which Comes First, Cardio or Weights?