Recently, one of my female clients noticed that she’s always stronger during the two days before and after her period started compared to the rest of the month. She has noticed dips in strength in between periods. She is not on birth control.
Another client I have noticed that she tends to be strongest during the two days prior to her period, but she feels like her strength is zapped on the day her period starts. She is on birth control.
I have long wondered about this phenomenon. Before delving into this article, my male readers who are involved in helping women improve their physical fitness might want to click HERE and HERE to learn more about the menstrual cycle.
Let’s Talk About Hormonal Fluctuations
Women on birth control experience different hormonal fluctuations compared to women who are not on birth control. See the graph below from THIS article: By the way, this has nothing to do with the topic at hand, but the linked article showed that mate choices fluctuated across the menstrual cycle, but using birth control eradicated the normal phenomenon. This is interesting, as it clearly demonstrates that during my single days, whenever a woman wasn’t interested in me, it was obviously not the right time of the month for her. I keed, I keed.
The most comprehensive experiment on the topic of hormonal fluctuations during the menstrual cycle appears to be from THIS article. See the graphs below – in order you will see the fluctuations of 17 alpha hydroxyprogesterone, 17 beta estradiol, androstenedione, endothelin 1, active renin, angiotensin II, atrial natriuretic peptide, luteinizing hormone, follicle hormone, follicle stimulating hormone, prolactin, progesterone, estrone, and testosterone levels throughout the menstrual cycle.
I’m not entirely sure how each of these could impact strength and hypertrophy, but I’m certain that testosterone (see HERE, HERE, HERE, HERE, HERE, HERE, and HERE) and estrogen (see HERE, HERE, HERE, and HERE) play large roles.
THIS study showed similar findings as the one above with regards to fluctuating hormonal levels, but notice that testosterone appears to peak the day prior to menses (aka period starting, bleeding).
Now Let’s Talk About Strength Fluctuations
As you can see, the large fluctuations in hormones could quite easily lead to large fluctuations in strength depending on the time of month for a woman. However, THIS article showed that strength was not affected throughout the menstrual cycle. So what gives?
Remember, research reports averages. Your body might not adhere to the norm. Moreover (this doesn’t pertain to the study above since none of the subjects were using birth control), as shown above, it depends on whether or not the woman is natural or taking birth control (and if she is taking birth control – which kind). But there’s more to the story…
A brand new study (click HERE to download the full paper) was just published showing some cool findings. First, testosterone levels are higher during the follicular phase compared to the luteal phase of the menstrual cycle. And second, that strength and muscle mass gains are greater during the follicular phase compared to the luteal phase of the menstrual cycle.
I checked into the researcher and located the student’s master’s thesis, and it appears that more publications are to follow. HERE the researchers show that these same trends do not exist in oral contraceptive users. They concluded that non-oral contraceptive (natural) subjects see fluctuations in strength and adaptations due to fluctuating hormonal milieu, whereas oral-contraceptive (pill) users have more consistent hormones and therefore more consistent levels of strength and adaptations. They also suggested the following: We recommend that eumenorrheic females without oral contraceptives should base the periodization of their strength training on their individual menstrual cycle.
What Does This Mean?
Ladies, you have a glaring additional variable in your training compared to men – your hormones fluctuate markedly, whereas ours do not. These fluctuations are much larger in women who don’t take birth control pills compared to women who do.
Start paying attention to your strength levels throughout the month. Do this for a period of around 6 months to get an accurate handle on whether or not your strength waxes and wanes. If it doesn’t, then don’t concern yourself with this phenomenon.
However, if it does, and you find that you’re consistently setting PRs during certain phases of your menstrual cycle compared to others, then you should “periodize” your training according to your periods (see what I did there? – ba da ching! – I’ll be here all night folks). Don’t try to set a PR when your strength is weakest. Instead, try to peak and go for PRs when your strength is greatest (perhaps right before or after your period starts, but it certainly depends on the individual). And don’t be alarmed if and when your strength dips during other portions of your cycle.