Atalanta, the Greek goddess of travel and adventure, was known for her athletic prowess that rivaled that of most men. Warned against marriage by an oracle, Atalanta came up with a plan to marry only a suitor who could beat her in a race, killing those who failed to outrun her. “I am not to be won till I be conquered first in speed. Wife and couch shall be given as prize unto the swift, but death shall be the reward of those who lag behind,” she exclaimed in the Roman poet Ovid’s Metamorphoses.
Many would-be suitors were beaten until Hippomenes fell in love with Atalanta and wanted to marry her. When hearing of the challenge, he was skeptical, but when Atalanta took off her outer garments for her next race, that was all he needed to send in his race entry. There was one problem, however. He knew he could not beat Atalanta, so he asked for help from Aphrodite, the goddess of love. Aphrodite provided Hippomenes with three golden apples to drop on the race course to distract Atalanta. During the race, whenever Atalanta pulled ahead of Hippomenes, he rolled one of the golden apples off the course, tempting a curious Atalanta to stop and pick up the apple. Atalanta’s frequent stops to fetch the apples were just enough for Hippomenes to win the race and Atalanta’s hand in marriage.
The menstrual cycle, which occurs monthly from a woman’s first period (age 11 to 14) until menopause (age 45 to 50), is the defining characteristic of women, and holds many secrets for how female runners should train for optimal performance.
The large fluctuations in the menstrual cycle’s major hormones—estrogen and progesterone—affect the female runner’s hormonal environment and, therefore, her physiology and training.
Female Physiology
A textbook menstrual cycle is 28 days (but can last up to 35 days) and is divided in half by ovulation on day 14, as the egg is released from the ovary. Although the menstrual cycle is complicated, an easy way to think of it is that the first half—the follicular phase—begins with your period and is dominated by estrogen; the second half—the luteal phase—begins with ovulation and is dominated by progesterone, although estrogen is also elevated in the middle of the luteal phase. The luteal phase ends with the start of the period, and the cycle starts over again.
The follicular phase typically lasts 14 days but can last 11 to 21 days. Following the period, which typically lasts 3 to 5 days, estrogen rises, peaking around day 14, right before ovulation, when it is 10 times the level it was at the beginning of the follicular phase. During the follicular phase, progesterone remains low.
The luteal phase always lasts 14 days. Progesterone rises after ovulation, while estrogen drops before rising again toward the middle of the phase. The increase in progesterone, which, at its peak in the middle of the luteal phase, is 25 times the level it was during the follicular phase, causes body temperature to increase to prepare for the fertilization of an egg. If fertilization does not occur, both estrogen and progesterone levels decrease abruptly in the second half of the luteal phase.
Changes in Estrogen and Progesterone Across the Menstrual Cycle
Menstrual cycle fluctuations in estrogen and progesterone have several effects that concern a female runner, including body temperature (which increases with increased progesterone), metabolism (which is shifted toward a greater reliance on fat with estrogen), breathing (which increases from increased progesterone), and bone density (which decreases with reduced estrogen).
Menstrual Irregularities
In a perfect physiological environment, your menstrual cycle will occur every month and always be the same duration. But that doesn’t always happen, especially among women who train with high volumes and high intensities and have a low percentage of body fat. They often experience irregular or even absent menstrual cycles, which reduce estrogen levels.
In response to heavy training, the first change in the menstrual cycle is a shortening of the luteal phase, followed by cycles without ovulation and, finally, cessation of menses, called amenorrhea, which is defined as having three or fewer periods per year, and results in constantly low levels of estrogen and progesterone. An amenorrheic runner experiences an estrogen-deficient state similar to that of a postmenopausal woman.
Consuming fewer calories than what is burned, rather than the stress of exercise itself, is responsible for the loss of the menstrual cycle. Consuming enough calories to replace the calories burned from running can prevent amenorrhea. Therefore, if you run a lot, you need to increase the number of calories you consume throughout the day to keep up with the large number of calories you burn by running.
Any disruption to the menstrual cycle can cause a decrease in bone density, increasing the risk for osteoporosis and stress fractures. Female runners with irregular or absent menstruation have significantly lower bone density than runners with regular menstruation and even compared to nonathletes, particularly at the lumbar spine.
An irregular menstrual cycle makes planning the training more complicated than when not having a menstrual cycle at all, because you can’t predict the months that will have a normal cycle and the months that won’t, unless the cycle is regularly irregular and therefore predictable. If the cycle is irregularly irregular, you need to plan your training month-to-month or even week-to-week.
With no menstrual cycle, women can train without consideration to the hormonal environment, since estrogen and progesterone won’t fluctuate throughout the month. It’s perfectly okay to run a lot without a menstrual cycle. However, in the face of a lack of bone-protecting estrogen, you need to take extra precaution in regard to your bone health, especially if you run a lot. Meticulously planning the training so that you avoid rapid increases in volume and intensity, calcium and vitamin D supplements, oral contraception to provide estrogen, and intense strength training to increase bone density can all help mitigate the risk for bone injuries.
Training
The female runner’s training program must always be open to change, moving workouts around based on the menstrual cycle’s hormonal fluctuations and on how she feels. However, few female runners or coaches take the menstrual cycle into consideration when planning training, in regard to both optimizing the training and injury prevention.
They spend too much time working in their training rather than working on their training.
Working on the training means developing a system of training that is specific to female runners. It means developing a system that works. The menstrual cycle is that system. But, guess what? You don’t need to create the system yourself. The menstrual cycle already exists. The system is already made for you! You only need to listen to it and follow it.
Before trying to get fancy or sophisticated with menstrual cycle-based training, the simplest (and insightful) way to implement the system is to keep track of how you feel and perform during your normal training. Write down each day of your menstrual cycle, the data from your workouts, and how you felt during each run. After a few months of documentation, you’ll likely notice a pattern. While harder workouts may be more challenging during your period, easy running may actually improve your mood and alleviate physical symptoms associated with your period.
Once you have the pattern, organize your training around your menstrual cycle so that you run more and harder when you feel good, and less and easier when you don’t feel good. That may sound simple, but most runners like to stick to a training plan, rather than be flexible, with their plan being fluid. To squeeze the most out of your training, your plan should be fluid, working with, rather than against, your physiology.
Plan increases in training volume to coincide with the follicular phase (especially week 2), when estrogen is high. Refrain from increasing (or slightly reduce) weekly mileage during your period and at times of the month when estrogen is low—early and late luteal phase (early in week 3 and late in week 4). Avoid challenging workouts around your period, especially if you don’t feel well or if you have major cramps or feel bloated (bloating occurs from the rapid drop in progesterone as you transition from the luteal phase to the follicular phase).
Menstrual Cycle-Based Training
The intensity of training can also be planned according to the menstrual cycle. For example, if you have a 28-day cycle starting on Monday, and your period occurs on days 1 to 3 (Monday to Wednesday), plan the hard workout, like a long tempo run or intervals, in the second half of the week to avoid your period. If two workouts are planned that week, schedule them either on Thursday and Saturday, Friday and Sunday, or Thursday and Sunday, or use a block periodization model, in which you congregate the stress with two to three hard workouts during the estrogen-high week 2 of the menstrual cycle, and just one hard workout the week of your period and the other two weeks. This block periodization approach also works well if your period lasts five days (Monday to Friday). You can also plan one hard workout the week of your period and two hard workouts each of the other weeks. If you are not adversely affected by your period and don’t experience much discomfort or cramping, you can always experiment with hard workouts during your period and keep track of how you respond.
Menstrual Cycle Block Periodization
Use the science of the menstrual cycle as your guide to create the basic structure of your training, and manipulate the details based on how you feel. With time, unless you have an irregularly irregular cycle, you will likely notice patterns that you can use to plan and manipulate your training. And if you train smart enough, you may even be able to beat Atalanta in a race… without having to roll a golden apple to distract her.