Why did that run feel so miserable? Maybe it’s hormones.


This past week I decided, kind of last minute, to head to a suburb and run a 5K to help support my running club. However, I also had to run 8 miles that day so the 5K would just be a part of my run.

And then I caught a cold. And a few days later I got my period.

Yes, we’re going to talk about periods. Feel free to skip this post if that weirds you out.

I took an extra rest day on Friday but my run on Saturday morning was, in a word, miserable. I did a two mile warm-up and was already dripping sweat. The 5K race started and I could barely hold an 8:00 minute pace. After the race I grabbed a water bottle from the finish line, turned around, and ran the course again to get in the rest of my 8 miles. I was struggling to keep a 9 minute pace when just the week before I breezed through a 7 mile run at a sub-9:00 pace.


Smiling even though I felt like death

I’ve always been curious about how hormones affect running and fitness because, anecdotally, I feel much stronger and faster the week or two before my period than I do the week of or even the few days before.

Turns out there might be something to that. If it’s been awhile since you’ve taken female anatomy, the menstrual cycle comes with ups and downs of estrogen and progesterone. Apparently estrogen is a “runner friendly” hormone and you feel better when estrogen is high. So, basically, days 10-20 or so of your cycle depending on the woman.


Progesterone is not as friendly and it also affects your body temperature set point as well as your breathing. This means you won’t start sweating until your body reaches a higher temperature and you might feel winded more easily. Kind of a problem when it’s hot or humid. So, running and working out is harder during days 20-28 or so.

Guess when my past two 5K races fell? Yep, during days 20-28. And it was humid at each race. BLARGH.

Guess when my marathon is scheduled to happen? During days 20-28. Also BLARGH.

Being a woman is so much fun, am I right?

Source 1 | Source 2 | Although I just realized both sources are written by the same guy. And why is a guy the apparent authority on this topic, anyway??


  • Monday 10/24 – 3.5 mile run + lower body strength workout
  • Tuesday 10/25 – Upper body strength workout + 4 mile run
  • Wednesday 10/26 – Rest
  • Thursday 10/27 – Lower body strength workout + 5 mile run
  • Friday – Rest
  • Saturday – 8 mile run
  • Sunday – Rest

5 replies on “Why did that run feel so miserable? Maybe it’s hormones.

  1. Emily @ Out and About

    Thank you for sharing this info, it is super helpful and informative. I always feel like death during the week before my period, too, and also during the first two days of my period. The week before I feel like a water balloon, and then during my period the cramps can be awful. It’s hard to get motivated to do anything physical during that time period, let alone run or work out. Being a woman is so much fun, indeed. =(

  2. Maggie

    Thanks to my Mirena IUD, I don’t really get a period anymore. (Very rarely I’ll feel a brief cramp and have a little spotting.) However, before the IUD, I remember plenty of days where I skipped (or really wanted to skip) my workout because of my period. I’m curious how being on hormonal BC affects the phases and what not. If I do have a day where I feel more tired than usual, since I don’t get my period, I have no idea where I am in a cycle (or if I even still cycle????) I should ask at my next gyno appt.

    But yeah. F’in uterus. Why do I even have one.

  3. Bethany @ Accidental Intentions

    I remember looking into this a couple years ago when my period was scheduled to line up pretty close with the Chicago Marathon (yay! Who doesn’t want that during a marathon? Haha.) and found it super interesting. I don’t at all remember the specific content of the article, but I do remember that it said certain times of your cycle are better for 5Ks and other times are better for marathons. Useful information, I suppose, if you’re looking to PR, but I’ve certainly never cared to take the time to count ahead and find races that match up with my hormonal fluctuations haha.

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