Salty Confidential: The Period Post

The site for women's running finally gets its punctuation together.
The site for women’s running finally gets its punctuation together.

The women at Salty Running are real. Real women living in the real world and dealing with real things. We’ve written about balancing career and running. We’ve written about balancing family and running. We’ve written about sex, depression, pregnancy, disordered eating and infertility. Yet there’s one thing we still haven’t touched. Something very real that happens to every single woman – or should happen to every single woman at some point in her life. And while it’s a little taboo and a little uncomfortable, it’s out there. You know it’s out there. And as a women’s running website, we should be talking about it.


So we’ve decided to bring it to the forefront with an entire series of posts about it. Tasteful posts. Educational posts. Posts that tell you not only what it is and what it’s like, but what it’s like for us. Real women dealing with real issues, including running with and around our periods. For this first post, we explain the menstrual cycle.

It’s been a long time since many of us got pulled out of class in fifth or sixth grade, and along the way many of us have forgotten a lot of what we’ve learned. As adults, the wonder of Kotex and the fear of the tampon have worn off, and unless we’re trying to conceive or have a diagnosed menstrual disorder the intricate workings of the cycle often get watered down to a circled date on the calendar, granny panties and making sure we have tampons with us. But it’s those intricate workings of the cycle – those forgotten stages, hormones and details – that actually have a real, scientific impact on our performance that goes beyond cramps or a nasty race morning surprise.

So we’re going to start with explaining all that stuff that’s going on in your body every single month. But we’re not going to stop there; after that, we’ll have a post about how all of this hormonal dirty dancing impacts your metabolism and by extension, your running performance. Following that, we’ll have one of our special Salty Roundtables, where the girls on the spice rack will open up – tastefully – about their own cycles and menstrual challenges. And to conclude, we’ll look at scientific and anecdotal evidence about hormonal birth control and performance: Does it make you gain weight? Does it make you slower? Are there certain hormonal combinations that are more runner-friendly? We’ll find out…and bring you the answers.

Oooo. Science!
Oooo. Science!

For the sake of simplicity, we’re going to start with the average girl’s cycle. We have every intent of getting into menopause and menstrual disorders down the line, but we’re keeping the science simple to start. The average woman’s menstrual cycle is anywhere from 21 to 40 days, and divided into three stages: the follicular phase, ovulation, and the luteal phase. Each of these stages comes with its own hormones and its own metabolic changes. We’re looking at hormones today, and we’ll dive into metabolism next week. But before we get into the nitty-gritty science of it, let’s start with just a few basic facts:

  1. The average menstrual cycle is anywhere from 21 to 40 days.
  2. A slight variation of the number of days month to month is perfectly normal.
  3. The follicular phase (the time from when your period starts to when you ovulate) can vary in length, and can easily be impacted by physical or emotional stress.
  4. The luteal phase (the time from when you ovulate to when your period starts) is alwaysthe same length, with normal phase length ranging from 10 – 16 days.
  5. When it comes to your actual period, periods are as individual as each woman herself. Whether three days or seven, just a nuisance or enough to keep you in bed, it’s generally “normal” as long as you don’t have amenorrhea (no period at all) or menorrhagia (dangerously heavy bleeding).
  6. It’s probably notanemia: the hormones at work during our cycles can make us feel exhausted, but unless you suffer from menorrhagia or already have an untreated iron-deficiency anemia, the typical woman doesn’t lose enough blood during menstruation to cause anemia.

Now let’s talk hormones.

Phase I – The Follicular Phase: The follicular phase begins with “day 1” of your period. Contrary to popular belief, the menstrual cycle doesn’t end with your period, but begins with it; the first day of your period is actually the first day of each new cycle. Two primary hormones are at work during the follicular phase: FSH, or follicle stimulating hormone, and estradiol, which is an estrogen hormone. The goal of these beauties is to stimulate a number of follicles in the ovaries to begin producing eggs.

While there are a number of secondary and tertiary hormones at work, it is FSH and estradiol (a form of estrogen) that lead the charge. Over the first several days of the cycle, the various developing follicles compete in a hormone-driven game of “Survivor,” with one follicle hormonally declaring itself dominant after several days. That follicle is the one that contains the single egg (usually) that will be ovulated that month.

We always assumed it was just the sperm, but those eggs can be so darn competitive.
We always assumed it was just the sperm, but those eggs can be so darn competitive.

While your follicles are busy competing for ovarian dominance and the chance to bear your future child, estradiol and its related estrogens are busy playing other games as well: thickening your uterine lining to make a home for (potential) baby and changing the consistency and acidity of your cervical mucus to make it more hospitable to sperm. Estradiol levels peak at the end of this phase, somewhere between days 10 and 20 for women with a regular cycle. Peak estradiol levels are ~200 pg/ml per mature follicle, a rise from >50 pg/ml at the start of menstruation.

Pop quiz: Did you know that the hormones at work in the follicular stage have a very real impact on your metabolism – and can ultimately make for faster, stronger speed workouts? Learn more in our next “Salty Confidential” post about the menstrual cycle’s impact on your metabolism and running.

Phase II – Ovulation: As you’re peaking out at ~200 pg/ml per follicle, a brand new hormone is asserting itself in girly-world: LH, or luteinizing hormone. The presence of all that estradiol (the wonder hormone) actually inhibits LH production until it reaches that peak level, at which point it does a big old 180 as a result of a hormonal threshold mechanism. So as that estradiol continues to rise, LH is suppressed until BAM! you hit that ~200 peak. At that point, LH literally surges into your bloodstream for approximately 48 hours. LH serves two very important functions: it is responsible for the final maturation of the egg, as well as weakening the follicle wall so the finished product can bust out of that ovary. Once the LH surge happens, ovulation typically occurs within 24 – 48 hours after. And once that egg busts forth from its ovarian prison, it has approximately 24 hours (that’s it) to meet up with its male counterpart – or game over.

Pop quiz: did you know that you are only fertile for three to five days per month – and that your window of opportunity for fertilization is only 24 hours?

Many women who aren’t trying to conceive don’t learn or know this. On the flip side, this is not an excuse to get adventurous with your birth control. Wonder sperm can live for up to five days, so even though you may only be fertile and “conceivable” for 36 hours, a wonder guy can start hanging out at the door as early as Sunday and still catch an egg dropped on Thursday. Yeah, busted. There’s a reason for birth control when you’re not trying to birth.

And you thought getting your period on race morning might ruin your PR chances.
And you thought getting your period on race morning might ruin your PR chances.

Women who are trying to conceive or want to know when they ovulate for other reasons (we’ll get to that) have any number of over-the-counter options for pinpointing this window. All the same companies that manufacture pregnancy tests have pee sticks that also check for the LH surge. Once you get a positive LH surge, you know that ovulation is 24 – 36 hours out, which means it’s time to get busy if you’re into the baby-making. It also means you can predict the exact date of your period – even on a natural cycle with no birth control.

A lot can go wrong in this phase: you can have an LH surge but not drop an egg. You can have a half-hearted LH surge, not drop an egg, and then have a second LH surge a few days later when you do drop an egg. You can have an LH surge and drop a non-viable egg that isn’t fully matured (I’m good at this). Or you can skip the LH surge altogether.

Pop quiz: Did you know you don’t ever have to have a race morning surprise again? There’s actually no such thing as an early period, and detecting your LH surge is the first step in predicting the exact day you’ll get your period. Learn more in our upcoming “Salty Confidential” Roundtable – we’ll not only tell you how to MOVE your period if you’re on birth control, but how to know for certain whether or not you’ll have it on race day – BEFORE race day rolls around!

But I digress. Onto phase 3, where everything goes haywire.

Phase III – Luteal Phase: As soon as that egg is dropped, the ruptured follicle it once lived in becomes something called a corpus luteum (“yellow body,” gross). The corpus luteum is a solid body, and it continues to grow for several days in the ovary. The egg is now in one of two places: disintegrated, dissolved and reabsorbed by the fallopian tubes (not pregnant), or fertilized, multiplying into a little blastocyst and tumbling through the fallopian tubes looking for the uterus.

The corpus luteum, meanwhile, starts producing massive amounts of progesterone. This ridiculous rising amount of progesterone is meant to do a couple of things, mainly make the uterus receptive to the potential blastocyst on its way, and prevent menstruation from starting too early – because if menstruation starts before the egg gets there, there’s no home for it. Except it’s a bit more complicated than that, so try to follow this next hormonal mess. If you can, I can almost guarantee you’ll never wonder why you get so cranky the week before your period again.

Here’s what happens: when you ovulate, our old friends FSH and LH cause the formation of that corpus luteum. Once the corpus luteum is formed, it starts flooding your body with progesterone so you don’t get your period. The increased progesterone levels send a message to your adrenal glands that it needs to kick up estrogen production – in case you’re pregnant. But those same hormones suppress FSH and LH – which are the hormones the corpus luteum feeds of off. So FSH and LH start dropping fast, which causes the corpus luteum to atrophy and basically commit hormonal suicide. Which means, of course, that progesterone starts dropping off at the speed of light, because with no corpus luteum to produce progesterone – no progesterone. And what does no progesterone mean? It means “not pregnant,” which means it’s time to shed that uterine lining.

When the yellow body jumps it's time to bust out the tampons.
When the yellow body jumps, it’s time to bust out the tampons.

Four different hormones spiking and dropping all at once? Is it any wonder you feel like crap?

Pop quiz: Did you know that your luteal phase is ALWAYS the same length? If you’ve ever assumed that all that stress the week before your period was due made it late, you’re not alone – but you are wrong. The follicular phase can be delayed by stress, ovulation can be delayed by stress, and excess stress can actually be the cause of having more than one LH surge. But your luteal phase will always be the same: mine is 12 days. Even on fertility drugs, once we confirm I’ve ovulated, I can count 12 days and know my period will come on the 13th. Every woman who is not on hormonal birth control can determine the length of her luteal phase – and know for a fact whether or not that period is due on race day.

Your period was early? Nope, it’s not stress, something you ate, or that marathon you just ran. You had a shorter follicular phase than normal and ovulated early. There’s actually no such thing as an “early period” – only early ovulation.

Which brings us back to the very beginning. No progesterone means not pregnant, which means it’s time to shed that lining. Your period has started, and the follicular phase is already beginning again. But that period itself can be a real pain in the arse – and the hormones are just the beginning. You may be dealing with any number of side effects and challenges, running the gamut from leftover bloating and water weight to headaches to fatigue to cramps to GI distress. We promise, we’re going to tackle it all. Every bit of it.

But for now, we need some help from you. What would you, our readers, really like to see us tackle? Metabolic effects on performance? What our periods are really like? How everyone from elite to hobbyist deals with it? The truth about birth control and running? Let us know your questions, “Seventeen” and After School Special style. We’re here for you – this is your site as much as it’s ours. Talk to us.

If you want to know more, check out the next post in this two-part series, The Period Posts: How Your Menstrual Cycle Affects Your Running Performance  and Garlic’s addition: The Period Posts: How Your Period Affects Injury.

Trail and adventure enthusiast. Girl who swears like a sailor but not when she's teaching Sunday School. Survived infertility without a successful pregnancy. Self-employed, primarily working for Clif Bar and Company. Thirteen 100-mile race finishes with seven top 3 placements. An original Saltine.

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  1. If you want to learn more about the inner workings of your menstrual cycle, I highly recommend the book Taking Charge of Your Fertility:

    This book breaks it all down and makes it easy to understand, whether you’re looking to make babies or just get a better handle on wth is happening in there every month. The book even has a website and apps for tracking your cycle and charting for ovulation:

    As for me, I had my period for EVERY freakin’ race I ran in the summer and fall of 2011 – the year I set most of my PRs. I had disappointing race after disappointing race. I can’t wait to learn what was going on with my body. I always just thought periods and cycle stuff were just mind over matter, and while that’s always true to some extent, sometimes there’s physical sh*t that we can’t surmount with a strong mind. I suppose this explains also, why every 4th track workout that same year sucked! Can’t wait for the rest of this series!!

    1. Taking Charge of Your Fertility is an incredible reference. If I didn’t have some major issues with my cycle (I’ll discuss in the roundtable) it would have made a lot more sense for me, but between marriage and wicked periods, going on the pill was best.

      What was most awesome when I was on the pill was that my period started at 10:00 am on Tuesday mornings – so for four years, I NEVER had it on race day, whether racing or pacing. Through my fertility struggles I’ve learned how to at least know for sure ahead of time.

      But I don’t want to blow the post wad here, so I’ll shut up now …

  2. I’m super excited about this “series”. I was on BC from 1999 until 2011 (age 19-31) and did not ever have a period from 2007-2011, part of that time I was doing tris so I’ve never trained with a period until now. Now that I’m off BC and I began running again it took me about 3-4 months to realize that my period was impacting my running. I’d love to hear/learn more about all of the topics you’ve hinted at. I sort of feel like I’m going through puberty all over again. I don’t really remember what it was like to have a cycle and I never had a “normal” one, hence the BC.

    Anyhow, I was just running last night and it was a preperiod run and it sucked, except for the great company of a female running buddy who totally gets why my run sucked. As you mentioned in the post the first day of my period is always my fastest pace day, I’m just hoping that my first half marathon ends up being day one of my period instead of a few days before my period. :-/

    1. We’ve got you covered, Tracie – several Salties have been on b/c and then come off of it. I had a roller coaster nine months when I first went off – I’d go 40 days without a period and then get a second one 21 days later. Keep reading – and thanks for reading already!

  3. I’m glad to see you doing this! I just actually had to reschedule an ablation procedure this week (due to weather) that I need done because my cycles are 21 days and my periods are horribly heavy. On top of that my ovulation pain that comes about 4 days after ending my period (middleschmertz) has become extremely painful and lasts for about 4-5 days! Ugh! 38 is not fun in the sense of womanly parts! 😉 What I would like to know is how the (seemingly) constant flux of hormones can affect metabolism and weight control. I just feel like I’m either bleeding or ovulating most days of a month. I feel like it is affecting my mood, my metabolism, my sex drive, my motivation… I’m excited to see what information you have to offer!

    1. Diane, so sorry to hear about the ablation. One of the things I haven’t had to face, but the plumbing part of being a woman is probably the least fun. Our post next week is going to cover metabolism, weight gain and sex drive so hang tight for more information. And we hope the ablation helps – a 21 day cycle just backs everything up against itself. Ugh.

  4. I’d like to know if there is any evidence that having your period on race day really does affect performance. My guess is it’s in our heads, but I’d like to know (or not–I’ll have mine on my upcoming marathon day!)

  5. Wow, I feel like I just learned more about my period in the 10 minutes it took me to read this then I did in all of sex ed in school. I would definitely be interested to learn about natural forms of birth control

    1. Get TCOYF! It will teach you how to track your cycle so you can use the “rhythm method.” But be careful! An extra glass of wine might throw off your math and you end up with an extra kid, not that I would know from personal experience or anything 😉

  6. I have charted some of my best runs – where I could go longer, run harder, and really push myself – two days before my period starts. This completely baffles me. But it always seems to happen! On the flip side, I have started three of my past five races with a heavy flow – and cramps. I generally bemoan the situation pre-race, and grouse a lot on the way to the race, but once I get started, it sort of evens out. Moving around seems to help the cramps, I guess. No, it’s not ideal. But I tend to joke about it and then move on. This scenario leads to some pretty interesting events, though – especially the “Holy S!@t! I forgot I put Icey Hot on my back this morning, and now that I’m sweating, it’s running down my you-know-what.” Yeah. Lesson learned. You’ll run awful fast to get away from that Icey Hot!

  7. I read this last week and was completely fascinated. Just late in getting here to finally comment. I’m looking forward to the series even though it won’t affect me 100%. I can better apply the knowledge to my 4 daughters and their activity, but for me I am on birth control. I”d love to learn more about bc and how it affects running & performance. I’m sure that is a broad topic (?) as there are so many types of bc. It still interests me. Great job on all the information!!!!