Nina Williams listening to her body as she warms up to train at The Front Climbing Club, Salt Lake City, Utah. George Bruce Wilson

I smear my toes against the greasy limestone at Hoback Shield, a sport crag near Jackson, Wyoming, and reach past the first roof on La Bamba (5.10a). Just as my feet slip, my fingers find a crimp. I crank on it and quickly clip the bolt above. As a newbie to the Teton area, everything feels sandbagged—so I’m surprised when, with a high foot and some manteling, I easily surpass the roof.

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It’s one of those precious climbing days when you’re riding the send-train, hands hitting holds perfectly, rock gluing to your skin. Clipping the anchor, I think, I’m a decent climber after all! though a week earlier, I was convinced of the opposite. I’d felt heavy, wrung out, and achy, bailing on climbs below my usual grades.

This pattern wasn’t anything new. In fact, I’d felt the waxing and waning of performance since I’d begun climbing five years earlier. I had a vague idea it was linked to pre-menstrual syndrome (PMS), since I’d often get my period soon after those defeating climbing sessions. But we all have stellar and not-so-stellar days on rock. It could have been anything: stress, lack of sleep, low blood sugar. Sure, PMS made me hungry, fatigued, and even emotionally tapped, but was it really affecting my climbing? And what could I do about it anyway?

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Then, I encountered the work of Stacy Sims. A triathlete and senior research fellow at New Zealand’s University of Waikato, Sims co-authored ROAR: How to Match Your Food and Fitness to Your Female Physiology for Optimum Performance, Great Health, and a Strong, Lean Body for Life with Ironman triathlete, cyclist, and pro mountain-bike racer Selene Yeager.

ROAR: How to Match Your Food and Fitness to Your Unique Female Physiology for Optimum Performance, Great Health, and a Strong, Lean Body for Life (Rodale, 2016)

Sims has made a career out of exploring the science behind female physiology, unraveling how our hormones affect everything from heat regulation to recovery to brain function. She began asking questions about female athletic performance as an undergraduate at Purdue University in the early 1990s, while a rower on the crew team. Her boatmates’ and her periods synced up, and Sims noticed that where they were in their cycles seemed to affect overall performance. In the lab, she asked about the pattern: Why, when her teammates were about to get their periods, did their times lag, while at other points in their cycles their performance surged?

Her professors pushed existing research on exercise physiology back at her. She looked at the studies and replied, “There’s no women.”

“For science, everything is male driven,” Sims says. Menstruation, pregnancy, and menopause struggle to garner attention because they’re seen as affecting only a “subset” of the population. Women are often considered difficult subjects because of their hormone fluxes. If they’re included in a study at all, the female subjects are typically in the low-hormone phase of their menstrual cycles, when they’re physiologically “most like men.” “If men went through any of this,” Yeager says, referring to menopause and menstruation, “ … it would be studied ad nauseam.”

But what research has been done is clear: Women’s physiologies are distinct. Training and nutrition need to be sex specific—just because it works for a man doesn’t mean it works for a woman. Yet, that’s how we’ve approached sports science for decades.

Before talking with Sims, I rarely considered how my hormones might interplay with my climbing or how my physiology differs from a guy’s. Maybe I didn’t want to. Almost all my climbing partners have been men. In climbing, which is still male dominated in many circles, acknowledging facets of your female body like your menstrual cycle can almost feel like making excuses. “Ever heard the quote ‘Anything you can do, I can do bleeding’? It’s my favorite,” Kathy Karlo, author of the blog For the Love of Climbing, told me. We lady climbers are tough, and acknowledging the needs and intricacies of our female bodies gives them the attention they deserve.

“You are not a small man” is Sims’s mantra. “So stop eating and training like one.”

Sidebar: Fuel the Fire

Brown rice: a high-quality carb. Ben Fullerton

"Don’t fast. As a woman, especially, it can make you fatter,” Sims cautions. Fad diets are never very successful, but for the female physiology, they’re doubly detrimental. Given how obsessed we climbers can be over our strength-to-weight ratio, this is a good reminder. Take the low-carb fad. Estrogen—at its max right before our periods—lends our bodies to “sparing glycogen,” which makes quick glucose energy in our muscles and liver inaccessible. That’s good for endurance. Women burn fat, the fuel for long hauls, expertly. But when we push our anaerobic thresholds, as we do in climbing, we need access to the quick energy of carbs. If we restrict that energy, we can’t perform at higher levels (let alone feed our brains, which use most of the glucose in our body). Even menopausal women who benefit from lowering carb intake still need some carbs. Axing carbs peaks our stress level and signals fat storage. It can even trigger serotonin release, making us sad. We end up slow, tired, foggy, and climbing poorly. Instead of obsessing over calories, Sims advises that you focus on consuming the “macronutrient medley” of carbs, fats, and proteins. A few pointers:

With carbs, the key is quality and moderation. Substantive carbs, like starchy vegetables and whole grains, should constitute 40–45 percent of your daily caloric intake. (This varies with body type, activity level, and age.)

Fat for the win. “A little fat makes everything better—flavor, nutritional value, satiety,” writes Sims. Fats should make up about 30 percent of your daily caloric intake and come primarily from unprocessed sources (e.g., olive oil, nut butters, and eggs). Omega 3-fatty acids, in fish and walnuts among other sources, are anti-inflammatories, too.

Build a love affair with protein. Sims calls it a “dietary superstar.” It facilitates strength and activity, muscle growth and repair, and fat loss, all of which are paramount for women given our hormonal balances. It should constitute 30–35 percent of your daily caloric intake. Seek complete proteins—those with all nine amino acids, like eggs, fish, and most dairy. If you’re eating incomplete proteins such as nuts and vegetables, pair them with other foods to make them complete (an easy method is combining legumes and grains). Timing is also key with protein, especially for women, given the interplay between hormones and muscle growth. About a half hour before a workout session, snack on 15–20 grams of protein and a smattering of carbs. You want tap-able energy to avoid muscle breakdown during activity. Post-workout, protein timing is even more crucial, because women have a small window to replenish energy stores before muscle breakdown. “We need protein, and we need it fast,” Sims instructs. She prescribes 25–30 grams of protein within 30 minutes after activity; again, combine that with carbs, since the combo hastens recovery. Skimping on food here will not help you lose weight because, much like eliminating carbs, starving your body of essential energy signals fat storage. Sims also steers clear of fruit for post-workout fuel. It’s high in fructose, which your liver will absorb before your muscles do. Instead, go with foods that pack a serious protein punch, like low-fat Greek yogurt, root vegetables, smoothies with whey protein powder, and PB&Js.

Ashley Schenck on Big Guy (5.11-), Indian Creek, Utah. Julie Ellison

Your Hormones And You

Sims starts lectures by telling students to turn to the person next to them and say, “Women have periods.” The students blush and laugh. But it makes them comfortable talking about menstruation.

“Many of my climbing partners are men, so you just don’t talk about how you’re feeling heavy and not strong because of your period,” says pro climber Heather Weidner. “With my girlfriends, though, it’s common to have them say, ‘I’m feeling bloated and I get it .… The project isn’t going down today.’”

The first step to biohacking your body? Understanding your period, says Sims.

Hormones—namely, estrogen and progesterone—orchestrate the whole shebang. They affect how we feel, sleep, eat, and perform athletically. A cycle generally has two phases: a low-hormone and a high-hormone phase. In the average 28-day cycle, the low-hormone phase marks the first two weeks (your period and the week after it), while the high-hormone phase comes in the second two weeks, up through any premenstrual symptoms.

Your low-hormone phase, with estrogen levels low (the drop in estrogen triggers the bleeding), is prime time for performance and training, according to Sims. Your body is not yet expending energy on baby prepping by releasing an egg and building a uterine lining, so you should feel stronger and recover quicker. Hence, my aforementioned “send-train” day right after my cycle began. For some women, estrogen levels might drop the day before, of, or after bleeding, which will affect when exactly you feel re-energized. But the point is this: Stop fearing your period on redpoint days.

Roughly halfway through your cycle, as you move into the high-hormone phase, the release of the egg, known as ovulation, happens. At this point, estrogen, progesterone, and other hormonal players ramp up. Unsurprisingly, you may be tired, bloated, hungry, and moody. More surprisingly, these hormones can raise your core body temperature, instigate headaches and upset stomach, and even dampen your spatial cognition—affecting your ability, say, to snag that precise deadpoint. At the same time, it becomes harder to build muscle and easier to break it down.

For Weidner, at least two days every month, she’ll feel tired, sad, and even doubt why she climbs. “As you can imagine, these are not my best climbing days,” she says. “Climbing is such a mental sport, and these days really affect my performance, or lack thereof.”

Plus, she’ll often feel bloated and “fat no matter what,” wondering if her metabolism is tanking or if she should get her thyroid checked. But then two days later, her PMS subsides and she’s back in the groove. “Just when I think I’ll have to start running again or just eating kale, magically I can see my abs in the mirror,” says Weidner. “So maybe I was just retaining water and I’m not fat from eating those cookies after all.”

But PMS isn’t intractable. Sims believes you can diminish and accommodate for these changes with thoughtful training and nutrition. During the low-hormone phase, when gains will be most easily achieved, she recommends focusing on strength training—a mix of non-climbing-specific exercises, like free weights and body-weight exercises, and climbing-specific exercises, like bouldering and campusing. (See “Get Powerful,” below.) Set your sights on your projects. Then, in the high-hormone phase and especially during PMS, allow for more rest and recovery. Think moderate climbing that maximizes aerobic capacity, like cruiser multi-pitch climbs or bouldering laps below your maximum grade. Or emphasize gentler climbing, like static or slab, versus pumpy, overhanging routes that are anaerobically taxing. You might feel gross, but activity helps. Karlo craves sushi and Netflix when she has PMS, but says, “I know that the thing my body wants more than anything is to stretch out and climb.” Just because you’re in a high-hormone phase doesn’t mean you can’t crush, either. Baseline-fitness considerations like V02 max and lactic-acid thresholds still matter.

Heather Weidner puts smart training to use to float Urisk The Rustic Brownie (5.11c), Waterfall Boven, South Africa. Austin Siadak

Of course, hormone baselines shift over time, and not always intuitively. If estrogen hampers muscle growth, its decline should do the opposite. But that doesn’t happen when our ovaries cease to function during menopause. Sims explains that decreasing estrogen enhances muscle growth, but that’s coupled by even greater muscle breakdown due to other changing hormone levels in pre-, post-, and menopausal women. Menopause can also slow metabolism and alter how our bodies handle proteins and carbohydrates. Women in these phases should especially emphasize HIIT (high-intensity interval training) and power-based workouts to invigorate stubborn muscles. Diet-wise, carbohydrates—especially simple carbohydrates, like baked goods and white starches—are more likely to spike your insulin levels and cause fat storage. By scaling back carbs and increasing protein intake, you can keep insulin levels steady and promote muscle maintenance. (See “Fuel the Fire,” as well as How to Maintain Climbing Strength as You Age.)

Sidebar: Get Powerful

With specific nutrition and training, females can increase lean mass, power-to-weight ratio, and type II muscle fibers—the fast-twitch type crucial for dynamic moves.

Sims recommends 2–3 days per week of strength training. One session should be sport-specific—i.e., any power-based climbing workout, like bouldering 4x4s (which boost your lactic acid tolerance) or a system/campus/hangboard session. The other two days should be non-sport-specific, like weightlifting and body-weight exercises. These include pull-ups, kettlebell and medicine-ball routines, and core exercises (key, as we women tend to over-rely on the hips for strength and stability; Sims praises planks, lunges, and bridges). As you build a robust base, switch to two sport-specific sessions and one general strength-training session.

Sims has three rules for building muscle: Lift heavy, lift often, and mix it up. Lifting heavy increases women’s proportion of fast-twitch fibers, which we genetically have less of than men. Your last reps in a 10-rep set should feel as difficult as possible while still allowing good form. She recommends at least 2–3 sets of 10 per exercise. Same goes for other workouts - i.e., those final seconds on the hangboard should verge on failure. Change your regimen every two weeks, cycling in new exercises and upping intensities , since your body will adapt.

“Be Your Own Biohacker”

Finally, “How do I feel?” is the most important question to ask yourself, in Sims’s opinion. You need to understand your physiology to support it appropriately. For example, women know that menstrual cycles are unique, with variable lengths, intensities, and symptoms. Track your period just as fastidiously as your training. These days, apps like Clue allow you to track bleeding, energy levels, sex drive, appetite, and mood, and will send you alerts about your upcoming period. And you can even try biohacking, from heart-rate monitoring to DNA testing to pee sticks. In 2012, Sims founded the sports-hydration company OSMO Nutrition, and Yeager was one of the testing guinea pigs. That meant drinking pre-hydration fluids, peeing on a stick, cycling up a hill, and peeing on a stick again. “It’s ridiculous when you’re doing it in the wild,” Yeager says. “We’re out on the town. It’s not like there’s nobody there. So we’d have to hide behind the dumpster or a car.”

But crouching behind a dumpster paid off. The urinalysis told Yeager she was losing protein, not consuming enough carbs, and not staying properly hydrated. “I would tend not to eat enough during the long days,” she says of their bicycling workout camp, so she amped carb intake to boost recovery. Similarly, when Yeager struggled with thermoregulation during the high-hormone phase of her cycle, Sims set her up with a hyper-hydration plan. It made a marked difference.

“It all seems small, but it actually adds up,” Yeager says.

To return to climbing, when you’re working a route, it’s often the small stuff that makes it go: that minuscule foot chip or that extra second you can hang that sloper. Similarly, if you’re protein starved, dehydrated, and out-of-sync with your body, you risk losing that final 1 percent of effort and ability. These days, I track my period on my phone. I do more planks and drink more water. I’m the girl at the crag with hardboiled eggs in her pockets and whey protein powder puffing out of her backpack. These small refinements add up to big gains: more “send-train” days and less “I’m-so-weak-why-do-I-even-try?” days. Supporting my body has made me a stronger climber, if not a happier one, and every female climber should feel empowered to do the same.

Sidebar: Birth Control and Your Cycle

Contraceptives throw another variable into the equation. Sims is wary of birth control pills and implants because adding hormones to your body can cause adverse effects, like a higher risk of blood clots. She instead recommends intrauterine devices (IUDs). The copper IUD does not release any hormones, and the others release progesterone locally. You may not even experience bleeding (ideal when you’re 1,000 feet up). That doesn’t mean your body stops producing estrogen and progesterone, though. “You still have the ups and down or hormones, and some women have fatigue and PMS symptoms even with no bleeding,” says Sims. There’s also the progestin-only mini pill, which typically has fewer side effects than the regular pill.

Drew Higgins is a Maine-based freelance writer, chronic Croc-wearer, and climber whose cuticles have bled on nearly every route she's attempted.