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.

Hip Thrust

Photos by Robert Reiff, courtesy of Oxygen Magazine

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.

Menstrual-cycle1

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.

2

Hormone Fluctuations: Normal Cycling Women (top) vs Pill Users (bottom)

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.

17 OHP and E2

17 OHP and E2

And, ET, PRA, A-II, ANP

Andr, ET, PRA, A-II, and ANP

LH FSH PRL

LH, FSH, and PRL

P4 and E1

P4 and E1

T

Testosterone

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 HEREHEREHERE, 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).

estradiol

Estradiol

progesterone

Progesterone

testosterone

Testosterone

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.

strength

Greater strength is built during the follicular phase

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.

24 Comments

  • Barbara says:

    Dear Bret,
    As a comediant, you’re a great strength coach. Just kidding, you did make me laugh. Eumenorreic women got nothin’ on me, PCOS ftw! Androgens in my blood all month long 😉

  • Em says:

    I love this article and THANK YOU Bret for talking about something that is not discussed very often! I noticed changes in strength (and fat mass) when I stopped taking hormonal birth control and went to the copper iud. The changes were amazing. There is so much to the puzzle that is not talked about, especially because birth control is a hot button topic, but I really appreciate you bringing it up and being willing to talk about it on a scientific level (read: no one can get peeved about your article being biased for personal or political reasons). I think that whatever you choose to do with your own body is your business, but understanding that any pill changes physiology inside your body is important. The more we can learn about those changes the more educated we will become on our life choices. And just as taking a medication or bcp is a life choice, so is working out and lifting weights. Since lifting weights is important to me (as is gaining strength) I love learning reading this type of article written by someone with your background.

  • Jen says:

    Oooh. That explains a lot!
    Day 14 = maximum beefcake day (that’s clearly a technical term haha) for me, week before period I might as well not even workout because I feel so grumpy and uncharacteristically negative.
    Thanks for putting some science here and helping me realise it’s not all in my head!
    Now to try and figure out how this periodisation stuff actually works (I’m fairly new to this fitness lark and by no means an athlete..!). I recently started doing CrossFit after I discovered I like weightlifting; it is kinda fun but do you have any suggestions as to how I might work my life better around my body when someone else is planning the workouts? Or maybe its not really possible..?
    Please go easy on the comments, the CF word seems to be pretty controversial on the interwebs, I am just trying to learn…

    • Shelley says:

      Check out Taking Charge of Your Fertility to learn about tracking your cycle. If you do progressive overload then once you’ve tracked your cycle for a few months you can schedule your workouts so they coincide best with your cycle – I.e. PR weeks when your strongest and deload weeks when you’re feeling crappy. Works like a charm for me.

  • Naina says:

    That looks like Amanda Latona!

  • Wendy says:

    I’m 52 and at the pre-menopausal end of my reproductive years. I’m not on any hormone based birth control (and haven’t been for decades.) I notice a slightly different pattern to the above, although just by my own casual observation, I’ve not measured it in any way. I find I have greatly reduced energy and strength in the days before menstruation, even less for the first couple of days after menstrual onset. My peak time for both energy and strength seem to be in the first couple of weeks leading up to ovulation.

  • Christine says:

    I was just discussing this with my coach. Its nice to see a study that correlates my experience with strength as I have been charting for the past few months. Hormones do have an affect on the metabolism as well. Hunger spikes during the luteal phase and weight loss efforts are easier during this time, which is a possible reason why strength gains are not as prevalent during this time. An small uptick in food requirements is likely needed. It would be interesting to see if the increase would result in more steady strength.

  • Anastasia says:

    My strength fluctuations don’t seem to depend on the cycle. Several things however do:
    * Bloating and increased bodyweight prior to menses make bodyweight exersices hard and frustrating
    * My diet adherence goes off the rails and I get crazy mood swings
    * My body needs more rest and takes a lot of time to recover
    So, when period comes, I ditch cardio, skip yoga classes (or do a very light “menstruation approved” complex at home), and focus on lifting weights. If I have cramps I deload the squat.

  • Cindy says:

    It’s interesting to finally see some articles here and other sites about this, I have been tracking this fluctuations in my hormonal level since I was teenager, both periods of time taking pills and not pills, this has been very useful to me for my weight loss (5 stones) and now during competition season (natural bikini fitness), I never understood why this has been like a kind of taboo but very interesting to read every single comment from other ladies 🙂
    Thanks for sharing

  • J says:

    This is really interesting,thank you!
    I’ve been researching the subject myself a bit because when i first started training i was on Depo-Provera and i had a very hard time making any gains. Once i stopped taking it the results just kept on coming.
    I know the studies didn’t find any conclusive evidence about Estrogen but in my case it made a huge difference.

  • Michael T. says:

    Dear Bret,
    I am most impressed with this article! The fact that you have done your homework on the female cycle and take it into consideration shows that you are serious about getting the best results for your female clients. My confidence in your work continues to grow…

    Since we are on the topic of reproductive factors influencing hormones and strength, I am curious about your take on the effect of ejaculation and strength in men. Old-school athletes abstained from orgasm days or even weeks before strength or competitive events, yet newer sources say those are just wives’ tales that have no relevance. The only thing I can find scientifically is the study of male athletes and their testosterone levels reaching a peak at 7 days orgasm abstinence. (I’ve never heard any ideas of orgasm effecting performance in women, but now that I think about it, I wonder if there are any relationships in women as well?) What are your thoughts??

    Michael T.

  • Sasha says:

    So glad you posted this! I have been “periodizing” (haha) for quite some time now. As a female, I know exactly when my menstrual cycle is goinv to take place. When you get to a certain age it’s an instinctive feeling. I am not on b.c. and for the last 5 months I have been lifting the day before my cycle (sometimes even on the first day) to gauge my gain in strength. I certainly see a huge increase compared to the last few days where my energy seems to drain.

  • Kate Boyden says:

    I’m 42 years old, athlete, NSCA-pt. A serious ski accident interrupted my incredible training routine, and leaving me with permanent limitations. Having difficulty “coming back” due to age, being a girl, and severe muscle atrophy, I’ve focused the last several months of my program design around the peaks and valleys of my cycle. I think it’s working. Currently 102lbs, 14% bf. Great to see you tackle this one Mr Contreras!

  • Candice Luciani says:

    Never noticed an issue with strength. I have a longer cycle than some women. Menstration doesn’t bother me. If I ache, I go work out and in general, I don’t have issues with it. I think it gives women an excuse to complain. Maybe guys should be on birth control too – then we can write an article about them…

  • anne says:

    How does this work if menopausal/no longer having periods?

  • David Brewer says:

    Great post. I work with a lot of young female athletes. I’m not always able to talk to them about this issue!

  • Emily says:

    It’s so good to see this stuff discussed in both a scientific and training environment! Finally!
    The only ‘correction’ I would make is about men’s hormonal fluctuations. Men may not have a monthly hormonal flucturation, but they *do* have a pretty wide range of hormonal profiles over the course of a day: https://www.youtube.com/watch?v=H2vN2QXZGnc

    Is there any research out there that correlates time of day, strength, and testosterone levels in men?

  • dani says:

    “Must have been the wrong time of the month” . . . CRACKED me up!
    And when women begin peri-menopause, life and workouts get even more fun and unpredictable! I’d love to see a study on that as well. Thanks for all the great info, as always, Bret!

  • Jenny says:

    Thank you so much for this article! I have searched recently for an article on this but could find nothing with any worthwhile information. The area I notice the most changes in strength in relation to my period is in my upper body. My push ups and pull ups change quite a bit. Pull-ups are already a weakness of mine, but exactly as you said, 1-2 days after my period, I can do the most pull-ups. I struggle the rest of the month and it’s quite disheartening to get so many fewer reps. Great article! Thanks!!

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