Few would argue that the hormonal changes that correlate with the menstrual cycle can have some pretty far reaching effects.
But it’s completely individual, of course. Symptoms can range from abdominal pain, nausea, and backaches to food cravings and irritability. Some women experience all of these while others are almost totally unaffected.
That variability makes it hard to make general recommendations, but we nonetheless set out to learn the answer to the question of whether the menstrual cycle affects strength, particularly for those who are preparing for a meet and need every gram of their lifts to be optimized on a given date.
What Is Happening to Your Body During Different Phases of the Cycle?
You can describe the menstrual cycle from the perspective of the ovaries or the uterine lining, but since the hormonal differences are linked to the ovaries, we’ll focus on that area.
“The ovarian cycle is split into two different phases, the follicular phase and the luteal phase,” says Dr. Spencer Nadolsky, a board-certified family physician, doctor of osteopathic medicine and author of The Fat Loss Prescription. “In someone with a perfect twenty-eight-day cycle — not that many perfect cycles exist — the follicular phase is the first fourteen days, during which the ovarian follicles mature until an egg is ready to be released. Then you release an egg from your ovary and your estrogen drops. Your basal temperature goes up by about a degree and your energy expenditure also goes up at this time, along with progesterone levels. If the egg isn’t fertilized, progesterone starts to decrease, which then signals menstruation and the whole cycle starts over again.”
Speaking broadly, many women report feeling more energized during the follicular phase, the first two weeks of the cycle, and more sluggish in the latter two weeks. According to Nadolsky, it’s probably due to the progesterone, a hormone that plays a role in maintaining pregnancy. It also increases your metabolism and temperature, but decreases how well your body uses carbohydrates.
So, if there are hormonal changes that affect energy levels and carbohydrate utilization, does it follow that you’re stronger at different stages of your menstrual cycle?
Strength and the Menstrual Cycle
One of the reasons it’s hard to know is because there are much more significant factors that can affect your strength levels than where you are in your cycle.
“Most women, and most people in general, just aren’t getting a lot of things right,” says Dr. Helen Kollias, the former research director of Precision Nutrition and an advisor to Girls Gone Strong. “There are so many other factors. Only if they’re at a point where they’re handling stress well, they’re eating properly, they’re working out regularly, they’re sleeping right, they have a good program, they’ve worked on postural issues, then maybe there’s a point where the menstrual cycle is playing a role.”
Dr. Kollias, who holds a doctorate is in microbiology in muscle development and regeneration and a master’s degree in exercise biochemistry and physiology, studied the effect of carb loading on men and women in long distance cycling and had to correct for menstrual cycles. She points out that it’s far easier to gauge the menstrual cycle’s effect on endurance sports, partly because measurements like VO2 Max make it easier to assess an athlete’s effectiveness.
“It’s harder to know why someone doesn’t lift more,” she explains. “Is it neurological, is it musculature, is it biomechanics? It gets more complicated.”
But the menstrual cycle definitely has a effect on fat oxidation and carbohydrate utilization — even if a male is using an estrogen patch, he’ll start oxidizing fat differently. Dr. Nadolsky notes that since there’s better carbohydrate utilization in the follicular phase, when estrogen is higher, an athlete may want to put more high intensity activity in this phase versus lower intensity in the luteal phase, which follows ovulation. In this case, high intensity means activities like sprinting and high-rep weightlifting, not heavy lifting.
“Hypothetically, the lower weight, higher rep lifting would use more glucose than the high weight, low reps would,” he says. “I don’t have a study to back me up, but potentially putting those lower intensity higher rep workouts in the follicular phase would make sense. The problem is that a periodization for lifters doesn’t usually last two weeks.”
Bottom line: cardiovascular and endurance exercise may be affected by menstruation, but it’s unclear as to whether maximum strength is.
Is There a Better Way to Measure Strength Levels?
In her experience as an exercise physiologist, Dr. Kollias has found that there’s too much variability and too many factors to be certain that where an athlete is situated in her menstrual cycle will affect strength levels. That’s why she’s a huge proponent of using HRV, or heart rate variability, instead.
“It’s a good indicator of general stress, and fluctuations in the menstrual cycle are reflected in HRV too, so you kind of end up getting everything under that measurement,” she says. “I would stress monitoring heart rate variability over menstrual cycle. That will basically tell you what your cycle is affecting as well as other stresses that you may not be able to detect. Otherwise, you’re kind of guessing.”
Whether it’s because of your menstrual cycle, a bad night’s sleep, general stress level, or other factors, your heart rate variability is a more reliable way to know if your body will perform relatively well lifting heavy weights in the gym.
If you’re unsure as to whether your menstrual cycle or other stresses are affecting your training, the idea is to wake up in the morning and measure your heart rate variability for a couple of minutes. Dr. Kollias likes the H7 Polar Heart Rate Monitor (about $55 on Amazon), which will work with an app like Elite HRV or HRV4Training. After a couple of weeks, the app will be able to tell you if it’s a good day for heavy lifting or a better day for recovery.
What If I Start Missing My Period During Contest Prep?
Missing a period, or amenorrhea, is usually linked more closely to energy deficits and stress than heavy lifting. This is why it tends to be more of a problem for bodybuilders and figure competitors than strength athletes.
However, if you’re cutting for a meet and start missing periods, then it warrants some concern. Amenorrhea doesn’t just mean your body has started sensing that food is too scarce and stress is too high for pregnancy, it can also lead to bone loss, decreased estrogen, and possibly issues with joint health. It’s wise to speak with your doctor sooner rather than later, as the longer amenorrhea is experienced the more difficult it can be to return to normal.
“If you become amenorrheic for a couple of months, it’s not the end of the world, but I’d refer someone to their doctor to make sure nothing else is amiss,” says Dr. Kollias. “In strength training and strength competitions, it doesn’t happen that often because athletes are less concerned by their body fat levels and the cutting window is shorter. But the longer it does, the more the body will question whether it’s safe to get pregnant and if there’s enough food out there. That’s one hypothesis, anyway.”
“The approach I would take would be to look at energy status. Are they cutting weight? Have they lost weight recently? If so, backing off the weight cutting would come first via diet,” says Dr. Nadolsky. “Taking a step back from training hard would likely be next, to allow the body to recover. This may be difficult in elite competition lifters where this is their livelihood. But in my opinion, it is something to take seriously, as I have had women who ignored it and went on to have long-term issues like bone loss and difficulties conceiving. Those long-term issues could have been prevented if intervened earlier.”
Since amenorrhea usually arises from relatively extreme calorie deficits — the kind that would hamper strength levels — it isn’t usually an issue for strength athletes. But if you start missing period, it’s important to speak with a physician, if only to rule out more serious problems.
Since most research has been conducted on the menstrual cycle and endurance training, it’s hard to know if it truly affects strength levels, particularly given the diversity in how different people experience their periods.
Conclusions are mixed; Dr. Kollias doesn’t think it has much of an impact on strength, and Dr. Nadolsky feels that it could potentially be beneficial to emphasize higher rep workouts in the follicular phase, the two weeks preceding ovulation. But neither expert is completely sold on the idea that the menstrual cycle is a major or reliable factor for strength athletes, which is why Dr. Kollias thinks HRV is a smarter way to predict your daily strength levels.
Featured image via @steficohen on Instagram.