What’s your favorite time of month? Chances are, it’s not the time right before your period. Hormones fluctuate, PMS brings on side effects, and, well, you just don’t feel quite like yourself. And while there’s absolutely no evidence you should stop exercising during this time, you may notice that you get dizzy, have muscle cramps, or headaches. Or, you may feel your performance is a little off. Here’s why.
Hormone basics during your cycle
Let’s clear up some confusion: a woman’s cycle starts on the first day of her period. And it ends immediately before her next period. Usually, this spans about 21 to 35 days. During that time, your body goes through a few phases: follicular, ovulation, and luteal.
Follicular phase: day one of bleeding through ovulation
The follicular phase also starts with day one of your period, or the first day you start bleeding. After menstruation, follicle-stimulating hormone (FSH) rises. About 5 to 20 follicles (with eggs) form on the surface of the ovaries. As you move through this stage, FSH begins to drop. Only one follicle and egg continue to develop. Estrogen rises.
Ovulation: usually around day 14
With estrogen levels elevated, your body knows to increase luteinizing hormone (LH). The follicle that developed during the follicular phase ruptures. An egg releases.
Luteal phase: post-ovulation through your next cycle
After ovulation, the luteal phase begins. What’s left of the follicle then forms a corpus luteum and triggers an increase in progesterone. As a result, the uterine lining begins to thicken. This thickening will help a fertilized egg implant in the uterus. If the egg isn’t fertilized, the corpus luteum dies. Progesterone declines and the thickened lining sheds. The tissue that sheds becomes the blood in your next menstrual cycle.
How your luteal phase affects your workout and how you feel
That increase in progesterone during your luteal phase? It can really change how you feel—in general and especially while working out. You may experience changes in respiration, heart rate, and electrolyte balance.
Changes in respiratory rate
Did you know your vitals change based on where you are in your cycle? In the luteal phase, progesterone levels rise. (The hormone progesterone is critical to having a healthy period, fertility, and maintaining pregnancy.)
Breathing rate naturally increases
The surge of progesterone you experience in the luteal phase causes your breathing rate to speed up. With an already increased rate of respiration, moderate-to-intense exercise can feel extra difficult. The reason: your body requires even more oxygen during exercise. It also produces more carbon dioxide. To give your muscles the nutrients they need and maintain carbon dioxide levels, your breathing has to pick up the pace even more. For some women, these accumulated changes in respiration can lead to shortness of breath and/or dizziness.
Changes in electrolyte balance
Along with changes in respiration, your workout might feel a little off due to electrolyte imbalance. Electrolytes help maintain the right amount of fluid in the body. They’re also affected by your cycle.
Sodium levels are at their lowest
A 2010 study showed the electrolyte sodium is at its lowest during the luteal phase. Now, also consider this: during physical activity, the number one electrolyte lost through sweat is sodium. Already low sodium plus heavy sweating can create an issue. If your levels drop enough, you could experience muscle cramps, dizziness, and salt cravings. In fact, most electrolyte-induced muscle cramps and dizziness during exercise are due to sodium loss—not potassium, like we’re led to believe. You may also find yourself a little nauseous or with a headache post-workout. Or, feeling more tired than usual.
Changes in pulse rate and blood pressure
Progesterone also affects your heart rate. It stimulates a pathway responsible for maintaining blood pressure and blood volume. This pathway causes the kidneys to release a substance called renin. Then, renin signals angiotensin—a hormone that causes vasoconstriction. (Vasoconstriction means your blood vessels constrict. This makes your blood pressure rise.)
Pulse rate and blood pressure become elevated
But exercise temporarily raises your pulse rate and blood pressure, too. Some activity increases both significantly and quickly. And, when you put the two together, some women feel “off.” You may find your normal routine has your heart rate elevated more than usual. It may feel like your heart is beating out of your chest. Or, you could feel dizzy or chest pressure.
So, should you change how you exercise if you have PMS?
That old wive’s tale of not exercising during your period? Not true. And there’s no reason to hold off on activity during your luteal phase or if you’re PMS-ing, either. In fact, exercise can boost endorphins, which may help ease cramps and other pain related to PMS.
The key is listening to your body. And, also knowing that hormonal changes can and do affect how you feel and recover from workout. If you are sensitive to hormone fluctuations, save moderate-intensity exercises for other times during your cycle. You may want to turn your focus to light-to-moderate aerobic activities for a few days, like walking or jogging. Or, head to yoga, tai chi, or another mind-body modality. The point is to nourish your body with what it needs, so you can feel your best.