Ok, we admit it. We coined that term, pun intended. Scientists use phrases like ‘menstrual phase based strength training programming’. Menstrual periodization is more concise and, well, interesting. More importantly, there’s hard science behind this concept. Women can gain more strength and muscle by designing their strength training program in accordance with their menstrual cycle. Here’s how.
Estrogen: convicted for progesterone’s crimes
Many hormone levels fluctuate across the menstrual cycle, so to understand menstrual periodization, we have to understand these hormones. Let’s start with estrogen. Estrogen is commonly vilified as the hormone that makes you fat and frail, a reputation based largely on the results of male steroid users. Yet this reputation of estrogen couldn’t be more undeserved for women. Estrogen is anti-catabolic and aids muscle repair.
Unfortunately, there is a hormone that does many of the things estrogen is accused of and that is progesterone. Ironically, progesterone’s catabolic effects seem to be partly the result of counteracting estrogen’s positive effects. For example, estrogen promotes glucose uptake in type I muscle fibers and prevents protein catabolism. Progesterone cancels out both of these positive effects. Progesterone also seems to inhibit your motor cortex, reducing the brain’s ability to recruit your muscles. Worst of all perhaps, progesterone can act as a testosterone antagonist, blocking testosterone from exerting its anabolic effects.
In short, estrogen seems to be beneficial for muscle growth, whereas progesterone seems to be bad news. The ratio between estrogen and progesterone thus influences the results of our training sessions.
Hormonal changes during the menstrual cycle
Estrogen, specifically estradiol, and progesterone concentrations fluctuate strongly during the menstrual cycle. From the start of menstrual bleeding to ovulation – the follicular phase – estradiol levels tend to be higher than progesterone levels. From ovulation to the start of the next menstruation – the luteal phase – progesterone levels tend to be higher than estradiol levels.
How estradiol and progesterone levels fluctuate across the menstrual cycle. Source
Testosterone levels also tend to be higher during the follicular than the luteal phase, though the variation isn’t nearly as large as for estradiol and progesterone.
Based on these differences in hormone levels, we’d expect training to be more effective for muscle growth during the follicular phase. But do the data support this theory? Let’s look at the scientific research.
Menstrual periodization: the research
In the graphic below we’ve compiled the research on how strength varies throughout the menstrual cycle. It is difficult to measure this, as training of course greatly influences your strength level at any point in time, as do multiple other factors. Still, as you can see, the trend roughly corresponds with the ratio of progesterone to estradiol. While a 2020 meta-analysis found no consistent, statistically significant effect of menstrual cycle phase on strength, many women are a bit stronger during the follicular phase when the estradiol to progesterone ratio is high. After ovulation, right about when the ratio reverses, strength levels decrease until the ratio becomes positive again. It’s not a major difference in strength, the exact pattern varies per woman and how strength is measured, and some women and several studies report no difference in strength across the menstrual cycle, but there’s a trend.
The difference in strength across menstrual cycle phases is typically not large enough to have direct programming implications. The week to week increase in strength from training should trump the menstrual phase fluctuations, so women should be able to implement progressive overload much like men over the course of each month.
However, even for women where maximal strength doesn’t fluctuate across the menstrual cycle, strength-endurance and maximal voluntary activation do, so they may reach higher levels of muscle activation and accomplish more total work in their training in certain phases of the menstrual cycle.
So both performance as well as the anabolic hormonal environment are generally favorable for your training from the start of menstrual bleeding until the end of ovulation. But do these changes significantly influence long term strength development and muscle growth?
Sung et al. put menstrual periodization to the test. 20 Women trained one leg with 8 workouts in the follicular phase and 2 workouts in the luteal phase for 3 months. The other leg trained with the higher training frequency in the luteal phase. The legs with more workouts in the follicular phase gained 42% more strength (maximum isometric force) and 46% more muscle (sum of 3 diameters) than the legs trained mostly in the luteal phase. Furthermore, the diameter of type II fibers and the nuclei-to-fiber ratio increased significantly in the leg that trained with higher frequency in the follicular phase; these changes were not observed in the leg with a higher training frequency in the luteal phase.
Earlier research by Reis et al. had compared training one leg with a constant training frequency of one workout every 3 days to a program in the other leg with a higher training frequency (every other day) in the follicular phase and a lower training frequency in the luteal phase. So same total workouts, just performed either regularly across the menstrual cycle, as most people do, or with a higher frequency in the follicular phase. The legs trained with menstrual periodization had a 33% increase in maximal strength compared to just 13% in the regularly trained leg.
In support of hormones as the driving force behind the effectiveness of menstrual periodization, there were positive correlations between the women’s gains and estradiol & testosterone and negative correlations for progesterone.
A recent study from 2017 confirmed that having a higher training frequency in the follicular phase results in the best progress. This study was longer (4 months), had more subjects (59), included only strength trained women and had 3 study groups:
- A control group training 3x per week across the whole study.
- A group with a higher training frequency in the follicular phases and lower frequency in the luteal phases (sensible menstrual periodization).
- A group with a lower training frequency in the follicular phases and higher frequency in the luteal phases (opposite of sensible menstrual periodization).
While not all tests reached statistical significance, the researchers concluded: “Our results indicate that, high frequency periodized leg resistance training during the first 2 weeks of the menstrual cycle is more beneficial to gain power, strength and to increase lean body mass, than the last 2 weeks.” In fact, the menstrual periodization group was the only group with a significant increase in lean body mass in the legs.
Only one study failed to find positive effects of menstrual periodization. In Sakamaki-Sunaga et al. 14 women performed 3 sets of 8-15 reps of arm curls 3 times a week during the follicular phase and once a week during the luteal phase with one arm, and performed the same routine once a week during follicular phase and 3 times a week during luteal phase with the other arm. The lack of positive effects here may have been due to lack of statistical power or because hormonal effects are not very relevant when only exercising 1 small muscle in your body. This study was also the study with the lowest training frequency of the literature on menstrual periodization.
Here’s an overview of the studies looking at when in the menstrual cycle higher training frequencies are more effective.
If you’re a woman with fluctuating hormone levels during the menstrual cycle, planning most of your workouts in the follicular phase of your menstrual cycle can significantly increase strength development and muscle growth. Alternatively, it is likely similarly beneficial to keep your training frequency the same but increase training volume during the follicular phases compared to the luteal phase. The late follicular phase is the ideal time for your muscles to exercise.
If you have a perfectly normal menstrual cycle of 28 days, the follicular phase consists of the first 14 days after the start of menstruation. However, a range of 22 to 36 days is considered a normal duration of the menstrual cycle. It can be useful to measure your body temperature to estimate your menstrual cycle structure. Body temperature tends to spike by at least 0.3° C around ovulation, the midpoint of your cycle between the follicular and luteal phase.
Ladies, it’s time to make those hormones work in your favor. Let Aunt Flow help you grow!
Special thanks to Joe Flaherty for his contributions to this article.
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