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.
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:
- The average menstrual cycle is anywhere from 21 to 40 days.
- A slight variation of the number of days month to month is perfectly normal.
- 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.
- 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.
- 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).
- 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.
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.
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.
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.