The dearth of sport science data exploring the physiology of women – and what works best for them training-wise – has significantly impeded the health and performance of professional female athletes
In November 2019, the revelations around Nike’s Oregon Project brought athlete well-being into global focus. In an explosive video op-ed run by the New York Times, runner Mary Cain spoke out about the alleged abuse she faced at the now infamous long-distance running training complex.
Her story reflects many of the challenges unique to chasing elite performance in a female body.
In recent years, the wider sports community has started to focus on the United Nations’ Sustainable Development Goals (SDGs) and how they can be promoted through sport. The fifth objective, or SDG5, is about accelerating gender equality. While the general consensus is that female athletes must have the same opportunities and support as male counterparts, there are other issues to address.
One such issue, that came to the fore in the aftermath of Cain’s damning allegations, is the huge physiological differences between males and females – differences that need to be taken into account when devising training and nutrition plans for athletes.
This much is clear: we simply can’t treat male and female athletes the same in this respect. Neglecting these differences actually restricts female athletes’ progress, development and opportunities to excel. More importantly, it also risks their long-term health.
A delicate balance
Cain described how her all-male coaching team became obsessed with her weight, weighing her publically and brutally shaming her when the scales reading didn’t please them. Any dips in performance were attributed to her carrying excess fat, despite her tiny frame. She was expected to be leaner, lighter, faster.
Believing that her coaching team knew best and wanting to do whatever it took to win, Cain lost the weight. However, it didn’t work out as planned. Malnutrition and overtraining took its toll on Cain’s hormones. Three years passed without her having a period. And as her oestrogen levels dropped, her bone density was compromised. She broke five bones and got slower and slower.
There’s a perception that athletes have to sacrifice everything to achieve their goals, including their health. That they’ll only achieve what others can’t by enduring things that others won’t. Sustaining overuse injuries, having health problems later in life and forgoing menstruation are seen as normal steps on the path to greatness by many of those inside and outside the world of elite sport.
But Cain’s sacrifices didn’t work. She was compromising her body’s ability to recover by undereating, leaving her body unable to recover from the hard training she was doing. This led to a condition known as RED-S (relative energy deficiency in sport, where the main symptoms in women are a lack of menstrual period, decreased bone density and disordered eating). If unchecked, it can also damage the cardiovascular and gastrointestinal systems.
She is convinced that her gender played a role in her body being pushed too far: “I got caught in a system designed by and for men, which destroys the bodies of young girls.”
The gender data gap
If you’re wondering why some of the best coaches in the sport didn’t recognise the warning signs, there is one key factor: the absolute dearth of evidence about how to train women safely and effectively. Overwhelmingly, the scientific data collected in sport focuses on men, creating a gender data gap.
The rationale behind basing studies on men is that the menstrual cycle, and especially the hormonal variation throughout it, introduces too many variables. Women are often seen by researchers as a complication, an anomaly that can corrupt a data set. The menstrual cycle is difficult, expensive and time-consuming to control for. However, if you want your findings to truly apply to 50% of the global population, it’s essential.
Omitting females from scientific studies means that there’s no way of knowing whether something that’s perfectly safe for men could be dangerous for women. Where women are included in studies, another difficulty is that the findings are rarely disaggregrated by sex to analyse differences between the results. This means that something that’s ineffective for men may be fantastically beneficial for women, but we simply won’t know about it.
The term ‘gender data gap’ was coined by author Caroline Criado Perez to describe the dismally low extent to which women are studied compared to men. She describes it as “a direct consequence of the tendency to assume that the average male equals the average human”.
One review looked at sports studies published between 2011 and 2013 and found that just 3% of participants were women. This leads to a lack of evidence-based information about what works for female bodies. Therefore, training protocols designed for men are pushed onto female athletes, with little regard for the significant physiological differences between the sexes that govern so many aspects of sport performance.
In a special report published by The Telegraph, Olympic medal-winning runner Marilyn Okoro described an unnamed elite coach in the US who both struggled in his interactions with women and refused to adapt training programmes for them. “He was good at coaching men,” she says, “but you can’t coach men and women the same.” She explains that she damaged her health trying to keep up for four years: “In 2017 I was put in touch with a physiologist, who did some testing on me and she said I was literally red-lining. She said she didn’t know how I was even running. She told me to rest for the rest of the year.”
Women are “not small men”
Dr. Stacy Sims is a leading expert on the difference between male and female physiology. A former athlete herself who competed at the Iron Man World Championships, she’s dedicated her professional life to helping athletes and their coaches understand that “women are not small men”.
Sims warns that a lot of the widely accepted ways to structure training and recovery aren’t ideal for female athletes because of how their hormones fluctuate throughout the month.
“Start with the typical three weeks on, one week off training model. That’s not appropriate for women. It was researched and designed on male athletes and their inherent sex differences from birth, from muscle enzyme activity to recovery ability from a time standpoint, nutrient timing – even things like heart rate variability are different between menstrual cycle phases.”
In the first half of a woman’s menstrual cycle, which starts on the first day of her period, her hormonal profile is generally more favourable for training and competing. For roughly two weeks, she can hit higher intensities. Her core temperature is lower, she has higher levels of sodium within her body so can balance hydration better, she can recover quicker. This is the time where most strength gains are made, and many women feel at their strongest, fastest and most energetic.
After estrogen increases at ovulation mid-cycle, it can be harder to hit high intensities in training, partly because it inhibits her ability to use carbohydrates for fuel. Her core body temperature is higher, meaning she can’t tolerate heat quite as well and gets fatigued quicker. She’s also less hydrated and flushes out more sodium, which makes it harder to drive blood to the muscles for extra power. Ironically, this can contribute to water retention, leaving her weighing and feeling heavier.
Additionally, the drop in serotonin can cause a ‘brain fog’, as well as increased clumsiness and reduced spatial awareness for some women. It gets harder to make strength or muscle gains at this point, and coordination-based training can be trickier too. However, the heightened progesterone has a calming effect on the body, which can make her sleep deeper – beneficial for recovery.
These cyclical hormonal shifts are one of the reasons a training regime that’s effective for men may not work well for women – at some points in the month, they can be physically impeded from peak performance, and will recover less between sessions.
Even without taking the menstrual cycle into account, there are other ways we know women’s bodies work differently to men’s. Women are three to six times more likely than men to injure their anterior cruciate ligament (ACL). This could be for several reasons, including womens’ tendons being more lax than mens’. Around ovulation in particular, a woman’s tendons are at their most stretchy, meaning her risk of a joint injury is highest as they provide less structural support.
It’s easy to see how an athlete willing to push herself beyond her limits could unwittingly push too far, frustrated by her body’s lack of cooperation at certain stages in her cycle or unaware of greater risk of injury during specific windows. It’s also easy to see how a coach without a solid understanding of what makes a woman’s body different could compound this.
Working with the body, not against it
It might feel like female athletes are at a disadvantage, but it’s simply that they’re different. We haven’t studied them enough, so we simply don’t understand them yet. By adjusting training, recovery and nutrition practices to account for the factors we do understand, we can unlock new levels of female performance which will be taken to greater and greater heights as we further develop our understanding of the female body.
Not all female athletes will experience dramatic surges during their cycle – some don’t notice intense symptoms or feel a need to tailor their training. However, this doesn’t mean it won’t affect their performance – in elite sport, champions are often made through the aggregation of marginal gains.
Other athletes choose to take hormonal contraception to keep their hormone levels balanced throughout the month. However, this isn’t without risks, as synthetic hormones can also compromise performance in various ways.
The Sustainability Report spoke to Dr. Emma Ross, head of physiology at the English Institute of Sport. She expands on this topic: “With hormonal contraception, the athlete needs to be empowered to make the right decision for themselves. They need to be educated about the role of the menstrual cycle first of all and what the different hormones contribute to within their body and behaviour, and then what hormonal contraception does. It effectively removes their natural cycle, so they don’t get the lovely highs in the same way, which can remove an advantage.
“For some athletes who experience severe menstrual or premenstrual symptoms, it might improve their performance by removing these symptoms, whereas other athletes might find it makes symptoms worse or creates new ones, or affects their performance in other ways. The most important thing is education, so they fully understand the choice they’re making. They need to fully understand the different contraceptive options and ask questions to ensure they’re making an educated choice.”
There are a wide range of mood or physical side effects sometimes experienced from taking hormonal contraception, but there’s one possible consequence in particular that might be more apparent to athletes. To vastly simplify the biological process, most of the types of synthetic progesterone in hormonal contraception seem to cause androgens (‘male’ hormones like testosterone) to be deactivated and flushed out of the body. Androgens are particularly important for female athletes because of their role in lean body mass, strength and competitiveness.
This adds yet more weight to the argument that we need to better understand women’s bodies. Research shows around 50% of female athletes take hormonal contraception, and we still don’t know enough about how it can affect their performance.
It’s also important to note that female physiology does provide a handful of advantages. Women are generally better at burning fat for fuel than men, although the extent of this advantage shifts throughout their cycles. This can confer an advantage in endurance and ultra-endurance sports, which we’re starting to see evidence of – Jasmin Paris won the 2019 Spine Race, a 268-mile fell run known as the world’s toughest endurance race, beating the nearest male competitor by 15 hours. The longer the race, the more women seem to be able to overcome men’s superior strength and lung capacity.
And in endurance swimming, the US swimmer Sarah Thomas holds the world record for the longest open water swim – almost 39 miles more than the men’s record. There’s potentially another advantage at play here: women naturally have higher body fat than men, which helps them float higher in the water, thus reducing the amount of effort and drag, and also helps keep them warm.
This proves once more that women should be better studied – what other physiological advantages are going untapped?
Some athletes have hit the headlines for linking poor performances to their menstrual cycles. Olympic bronze medallist swimmer Fu Yuanhui (below left) mentioned hers as a factor in her Rio 2016 relay performance: “My period came yesterday, so I felt particularly tired – but this isn’t an excuse, I still didn’t swim well enough.”
Athletes talking openly about the effects of their cycle on their ability to perform is an important step – as is acknowledging like Yuanhui did that it’s only one of many factors at play.
It’s not only key that athletes raise this issue publicly, but also that they talk about it privately with their support teams. Every woman experiences her cycle differently, and it can change over time, so it’s vital to keep the subject open.
It’s understandable that some women may be reluctant to discuss this aspect of their health. Culturally, it remains taboo in many societies. Dr. Ross also finds that some athletes are reluctant to talk about it for another reason.
“Female athletes have fought so hard to receive the same opportunities and prize money as men, and to be allowed into the same spaces. It can be difficult to talk to them about these differences because they don’t see themselves as female athletes, they’re just athletes, and they often don’t want to be treated differently to the men. When we frame understanding their cycle and working with it as a potential competitive advantage they could be missing out on, that’s one way of engaging them.”
Admitting that periods can inhibit our performance feels like it sets female empowerment back a little. However, increasing awareness is an important step in developing our understanding of this aspect of female athletic wellbeing.
One target of the SDG5 is to enable technology, in particular information and communications technology, to promote the empowerment of women.
One simple technological tool we can harness to improve female athletic performance is a period tracking app. FitRWoman is an app designed by sports scientists for female athletes. It doesn’t just track a woman’s cycle, it provides information on what her hormone levels are doing at each stage, and evidence-based nutrition and training advice to help her optimise her performance. Athletes can also log symptoms, which provides the opportunity to spot patterns in their energy levels, recovery, hunger levels, sleep quality and anything else relevant to their performance.
Dr. Ross explains: “One of the most valuable things any female athlete can do is to track their cycle. Whether it’s with an app or a calendar or whatever else works for them, they need to understand how their hormones and performance and emotions shift throughout the month.
“If they’re tracking it, we can start to anticipate how they’ll be feeling at certain points. We can then explore natural supplements or nutrition, or certain exercises or mental exercises to overcome any challenges that might inhibit performance, and we can also make sure we’re harnessing the points when they feel amazing to capitalise on them in training.”
There’s a coaching version that sits alongside it where athletes can give coaches permission to access their data. Coaches of team sports can even track their whole squad’s cycles, enabling them to monitor their health.
What sports organisations can do
Organisations need to drive education and awareness. Staff must constantly challenge their assumptions, remain up-to-date with developments in sports science and use it to inform their decisions. Where possible, organisations should also use their influence to put pressure on research bodies to include women in studies and disaggregate their findings appropriately – or conduct this research themselves.
The English Institute of Sport’s SmartHER campaign was set up to help elite British female athletes be healthy, happy and deliver world-class performances, taking into account all the variables that might block them from achieving those goals. This involves “working with amazing researchers who specialise in studying athletes to really expand our knowledge and understanding of the female athlete”.
“The data isn’t there yet to enable us to tailor training around their individual cycles, but we’re doing some really exciting research and we think it’s on the horizon”, Dr. Ross adds.
“Over the last few months we’ve [also] been delivering workshops for coaching and performance support teams to allow them to further their understanding of some of the fundamentals of the female athlete. We’re now taking those workshops out to athletes.
“I would encourage athletes, coaches and practitioners to be comfortable talking about these things, as they are an integral part of the jigsaw of support that we need to put around an athlete in order for her to pursue world-class performance.”
There are big gaps in our knowledge of the female body. But by ensuring everyone in this jigsaw of support – including the athlete themselves – understands as much as possible about how their body works, we do so much more than optimise their performance. We keep them in the sport for longer, we push the boundaries of what women can achieve and we set female athletes up for healthy, happy lives both during and after competitive sport.