Caroline Criado Perez: How sports science is failing women

Science’s failure to understand how women’s bodies react to exercise differently to men’s poses serious health risks, writes author of best seller Invisible Women, Caroline Criado -Perez

Every morning, without fail, I wake up to the same two words on the BBC World Service bulletins. They come at just past the hour and just past the half-hour. They are “the sport”.

Only, what they describe is not the sport. It is the men’s sport. Almost universally presented as if it is the sport, just as in medicine the male anatomy is presented as the anatomy. And so the message that I – and millions of girls and women around the world – get every morning, is that sport does not belong to us. This is a message that women have internalised, and it is not just BBC announcers who are spreading it.

It is in gym equipment that is set too high for us to reach or too wide for us to grip. It is in the torture devices otherwise known as sports bras that often seem to have been designed without reference to an actual breast.

It is in treadmill calorie calculations set to an average male height and calorie burn (men, on average, will burn eight per cent more calories than women of the same weight) and in fitness monitors that under-estimate steps during housework by up to 74 per cent while being within one per cent for normal walking or running.

Calories are not everything, of course, but there is an irony in these metrics not working for women, given the immense social pressure women are under when it comes to weight loss. And trivial as these examples might seem, they are a symptom of a far larger problem – one that can have life-or-death consequences for women. I am talking about the gender data gap.

The gender data gap is a direct consequence of the tendency to assume that the average male equals the average human. And it crops up everywhere. From car-crash test dummies being designed around the average male body, leaving women 47 per cent more likely to be seriously injured and 17 per cent more likely to die if involved in a car crash; to stab vests that do not accommodate women’s breasts and therefore leave their bellies exposed; to heart medication that, at a certain point in a woman’s menstrual cycle, is actually more likely to trigger a heart attack. These are all results of seeing men as the standard human, and therefore not bothering to either collect data on, or design for, women.

One of the worst areas for the gender data gap is sport science. In 2014, the European Journal of Sport Science published a paper entitled: “Where are all the female participants in Sports and Exercise Medicine research?” Well, wherever they are, they certainly are not in the research, the study concluded. A 2016 review found the same problem: 27 per cent of studies were all-male, while for the 73 per cent of studies that involved at least some women, “some” was the operative word.

The March 2016 issue of the Journal of Sports Sciences had a “dismal” female participation rate of only 12 per cent.

This leaves researchers who do take an interest in women complaining of a “limited understanding” and an “inadequate number of published studies”. There is “much less information” on female bodies and “several fundamental questions remain unanswered”. A perennial cry of the sports scientist when it comes to women is: “We just don’t know.”

A random sampling of things we do not know includes sex differences in how muscles tire; if women’s muscles respond to protein in the same way as men’s; if women’s metabolisms respond to exercise in the same way; how women respond to concussions (“even though women suffer concussions at higher rates than men and take longer to recover in comparable sports”); if women regulate their body temperature differently; the female ventilatory response to exercise.

The general advice for endurance athletes is to carb-load, with at least one expert specifically advising against fat-loading.

But it turns out that this standard pre-race advice is based on studies in men. And it does not hold for women, who have to eat 34 per cent more calories than they usually would to achieve even 50 per cent of the performance benefit men experience from carb-loading. Which may not be an “appropriate strategy” given “the potential deleterious effects on performance” of overeating. Rather, the authors suggest, because women burn more fat than men during endurance exercise, they might be better off fat-loading. Might. We do not know, because, of course, “few studies examining the effects of fat loading […] on performance have included women”.

Some data gaps are less amusing. If you run a general search on whether resistance training is good for reducing heart disease, you will come across a series of papers warning against resistance training for people with high blood pressure, largely because it is not as effective at lowering blood pressure as aerobic exercise and because it causes an increase in artery stiffness.

Which is all true. In men. Who, as ever, form the majority of research participants. A paper that did include female participants found that not only is resistance training more effective at lowering blood pressure in women, women do not suffer from the same increase in artery stiffness. And this matters, because as women get older, their blood pressure gets higher compared to men of the same age – and it is a greater mortality risk in women. It also matters because commonly used antihypertensive drugs are less effective in women than in men.

So, to sum up: for women, the blood-pressure drugs (developed using male subjects) do not work as effectively, but resistance training just might do the trick. But we do not know either way, because all the studies have been done on men. And this is before we account for the benefits of resistance training in counteracting bone conditions such as osteopenia and osteoporosis, both of which women are at high risk for post-menopause.

Sticking with osteoporosis, the impact of default male sport here can start early. Officials in the Swedish city of Gothenburg found that the majority of public sports funding (80 million Swedish krona, or £6.6 million) was going to boys. Most readers will be unsurprised by the report’s conclusion that the failure to invest in girls’ sport contributed to poorer mental health in girls. More unexpected, perhaps, is the claim that investing in girls’ sport could reduce the health cost of fractures due to osteoporosis. Physical exercise increases young people’s bone density, reducing the risk of osteoporosis later in life, with research suggesting it is especially important that young girls begin exercising before puberty.

The total cost to Gothenburg of the estimated 1,000 fractures a year resulting from falls (three-quarters of which are suffered by women) is around 150 million krona (£12.37 million). Women account for over 110 million krona (£9 million) of this. “If an increase in the city’s support for girls’ sports of 15 million krona (£1.24 million) can lead to a 14 per cent reduction in future fractures due to osteoporosis,” concluded the report, “the investment will have paid for itself.” So, not so trivial after all.

The gender data gap in sport – as everywhere – is a direct consequence of the way we conceive of men as the default. Because we do not think of women as half the global population, we forget to study them. We forget to design for them. And this is costing women their wellbeing, and sometimes even their lives.

It is time to start taking the costs of default male seriously. Women are not outliers. We are half of humanity.