Until a few years ago, elite Colorado track and field athlete Annie Kunz used to feel fatigued — even during her warmups. And then there was the constant hunger: Sometimes her stomach would growl in the middle of practice. She felt like she was always thinking about food, always restricting what she ate, avoiding whole categories — such as carbohydrates — completely, because she thought they were unhealthy. Add to that awful, debilitating cramps when she got her period. Kunz, who is representing the U.S. Olympic team in the women's heptathlon this week in Tokyo, just didn't feel like she was performing at her best much of the time.
Any of the above could be signals of an underlying health problem and could also affect her performance. But Kunz says she rarely, if ever, discussed these issues with her coaches. They've almost always been men, Kunz says, many of whom just weren't used to broaching topics such as weight, hormones and menstrual cycles with their female athletes.
Kunz moved to California after graduating from college in 2016 to focus on preparing for the Olympic heptathlon — a competition with seven events that requires strength, speed and a heaping amount of all-around athleticism. She sought out advice to improve her health and performance and learned that recent research on females in sports has yielded insights that could help.
In 2018 she worked with someone well-versed in that research who helped her focus on getting enough calories as opposed to restricting what she ate and encouraged her to track her menstrual cycle, along with its impact on her performance, mood and energy level.
As Kunz gained more knowledge about what works best for female athletes, she also made sure to be more open about her cycle with her current coach. She and her coach have also shifted Kunz's physical focus — from getting leaner to getting stronger.
"It's literally just been a world of difference," Kunz, 28, said before she left for Tokyo and her first Olympic Games. "I never have those days anymore where I'm just dragging to warm up. I come with energy."
At the Olympic trials in Eugene, Ore., in June, Kunz not only won the heptathlon but posted the fifth-best heptathlon performance of all time — a far cry from her eighth-place finish during the 2016 trials. Building her training regimen around recent findings from sex-specific sports medicine research has made a difference in her performance, she says.
A relatively new field of study
When Dr. Kate Ackerman was in medical school 20 years ago, she'd heard of the term "female athlete triad." Coined in 1997 by the American College of Sports Medicine, it described the constellation of three disorders — amenorrhea (a lack of menstrual periods), bone-thinning osteoporosis and disordered eating — that is sometimes seen among women athletes. It's triggered by extreme exercise and low body weight. But other than that descriptive term, Ackerman says, not much sports science research had been published about female athletes. Almost all such research up to that point had focused on males, which meant those findings became the standard.
"There was not really sex- or gender-specific training [for athletes]," says Ackerman, who competed as an elite athlete herself on the national rowing team during her med school years. She and her teammates often had questions about their menstrual cycles and birth control options, and whether any of those things affected training, she says, but finding any science-based answers at the time just turned up "a void."
Thanks to Ackerman's research over the past 10 years, along with work by others in the field, the female athlete triad is now often more broadly known as relative energy deficiency in sport, or RED-S — essentially, a problem of athletes underfueling. It's that lack of energy from not ingesting enough calories relative to what you are expending, says Ackerman, that can lead to a whole suite of health problems that go beyond irregular or missing periods and decreased bone density. RED-S can also include depression, impaired cardiovascular and immune function. The physical strain can negatively affect athletic performance as strength is reduced and the likelihood of injury increases.
Breaking through the "thinner is faster" myth
Some of what drives athletes into this disorder, Ackerman says, has to do with messages that many receive from their coaches and trainers, a philosophy she sums up as "thinner is faster" or "lighter is better."
The message that athletes in some sports need to slim down to perform better has been common for years.
"I've definitely had coaches in soccer and track that just bluntly would be like, 'If you lost 10 pounds, you'd be so great,' " Kunz says. She believed those coaches, tying her weight to her performance. "I wouldn't say I've ever had an eating disorder, but I definitely think it was something that weighed heavy on my mind a lot," she says.
Earlier, small research studies had suggested that male endurance athletes with lower body mass index outperform others. But more recent research — studies that include female athletes — has shown that this correlation does not hold for many people in sports, especially for younger female athletes.
Maya DiRado, a four-time medalist at the Rio Olympics in 2016, says that while she was on the swim team at Stanford University, the message that athletes should focus on thinness seemed clear.
"In those early years of my collegiate career it was believed that there was a 'swimmer body type' and we should all try to get leaner and more toned," she says. But that advice didn't sound right to her, she says, even then. "I think with swimming, especially, that's just so demonstrably not true when you look out at the pool deck [of competitive swimmers]."
She's right, say researchers in the field. The science around RED-S shows that a one-size-fits-all approach to body weight or caloric consumption isn't healthy for athletes regardless of gender, or good for performance.
Alicia Glass, a senior sport dietitian for the U.S. Olympic Committee, has been working with USA Track & Field and USA Swimming for the past decade. "It grinds my nerves so badly when I get emails from coaches that just say — and I get a lot of them — 'What is the average body fat percentage of X national team?' " she says. "That totally misses the point. If we focus on choosing the right foods, looking at how much carbohydrates and how much protein your body actually needs to complete exercise, your numbers fall in place. They take care of themselves. But just focusing on body fat percentage — it does a disservice and it totally misses the target."
Even many doctors are unaware
Even with sex-specific research in sports science more common now, it is a nascent field. "Even today," Ackerman says, "I see [female] athletes all the time who don't know about it and don't necessarily see physicians who are comfortable treating RED-S. So we still have a lot of work to do."
A good way for doctors to start a conversation with female athletes who may be experiencing RED-S symptoms or warning signs is to start with diet, she says. "I think of nutrition as a bit of a pyramid. First, make sure you're getting enough calories — make sure you're eating enough just to do this, and then we can tweak what kind of calories and timing of calories ... before we get to the specific, 'OK, you need this supplement on Day 17 of your menstrual cycle.' We've got to cover the basics."
Even those basics can be hard for some athletes to hear, especially for females who have been getting calorie-cutting messages for so long. "You can't just walk up to someone and say, 'Eat more,' or 'Eat less,' " Glass says. But they can be convinced.
"Athletes should care about staying healthy and not getting injured. So focusing on the wellness side — of being able to manage the workload, complete the whole phase of training and feel really good about it — that's really where the focus should be," she adds. "The health and performance, not the numbers."
Menstrual health is key
Even though more people in the athletic world these days understand menstrual health is a key indicator of health for female athletes, it can still be a tricky conversation to start. When DiRado was competitively swimming, for example (she retired after the 2016 Olympics), she never had a regular menstrual cycle, she says, and doesn't remember ever being asked about her cycle by coaches or support staff, unless something drastic prompted it.
DiRado remembers one of the rare times she did get her period during her college career: Her nausea was so bad she had to get out of the pool and lay on the concrete at 5:30 a.m. because it was the only thing that made her feel better. Even then, she and her coach just felt confused, DiRado says. Now she finds it odd to look back and realize that maintaining a regular menstrual cycle wasn't seen as a priority. "I had no concept of what my body was going through, even though in so many other areas, I was so finely attuned to how it was feeling and what was happening in it."
Glass, who worked with DiRado during her time with USA Swimming, says she's now proactive about menstrual health, routinely asking the athletes she works with, "Are you getting your period every month? Do you know how long your cycle is? Do you know how heavy it is? Have you acknowledged how heavy it is and how it relates to how you feel?"
A healthy menstrual cycle can vary quite a bit in its length or the heaviness of bleeding, and everyone's hormonal levels are different, she notes. She encourages athletes to keep track of their symptoms every month. Issues such as cramps and cravings, which can affect performance, can be addressed through nutrition, she says. She advises athletes to eat more anti-inflammatory foods, such as strawberries, raspberries and other fruits and vegetables, before they expect cramps to start, and to consume well-timed, small quantities of dark chocolate when sugar cravings normally kick in.
Kunz, the heptathlete, says keeping track of changes in her own physiology has made a big difference for her, as has a growing willingness to be candid and matter-of-fact with her coaches. She says she might say something to her coach like, "It's my week and my self-confidence always drops during that week. ... Let's not take too much to heart this week." And if she's extra fatigued and needs more naps that week, she tells her coach.
What's next in research?
Ackerman and her colleagues are eager to learn more specifics about how the menstrual cycle affects performance. "The next step from a research standpoint," she says, is "What is estrogen's effect on strength? So when you have a higher estrogen component, and a lower progesterone component, what does that do for endurance? For strength? Do you get different training benefits at these different phases?"
Researchers say the sorts of improvements that Kunz and other female athletes have seen in recent years are just a start.
"We are applying so much information to women that is based on men," Ackerman says, "that once we start doing these studies in women that are specifically for women and having results that we can then apply to women's training, I'm anticipating that we will see huge improvements in performance. We have not even begun to tap the potential of female athletes."