How Exercise May Change Your Period

There are many changes in your body that can happen when you start to exercise regularly. You may have sore muscles, lose weight, sleep better, and gain strength. But what you may not expect is that regular exercise can also cause changes in your menstrual cycle.

The changes may be subtle or extreme depending on how your body reacts to your increased activity level. This article covers four of the most common effects exercise can have on your period.

Breakthrough Bleeding

Regular exercise can cause subtle changes in your hormone levels. The lining of your uterus may respond to these mixed hormonal signals by randomly shedding, which causes breakthrough bleeding.

Breakthrough bleeding is a common type of vaginal bleeding that happens outside your regular period. You may have heard this referred to as spotting.

The blood may be dark or bright red in color, and the flow is typically lighter than your regular period. You may also have breakthrough bleeding during or right after intense exercise.

Bleeding after exercise could have a few different causes. It could be the result of a disordered endometrium (the innermost uterine lining). Or, it could be due to structural changes in the lining of your uterus or cervix.

Missed Periods

Exercise is generally good for you. But for some people, the stress that intense exercise places on the body can interrupt the balance of hormones that drive their menstrual cycle.

The hypothalamus is a structure in your brain that acts as the control center for your menstrual cycle. It sends hormonal messages to your pituitary gland and your ovaries, which in turn trigger ovulation.

If this communication gets interrupted by something that causes your body stress, like intense exercise or significant weight loss, you will not ovulate. If you do not ovulate, the changes that trigger your menstruation will not happen and you will miss your period.

An extreme form of exercise-induced amenorrhea is known as the female athlete triad. The female athlete triad describes a specific condition in adolescent and young female athletes who experience the following:

• Menstrual cycle problems
• Low caloric intake
• Low bone mineral density

The combination of intense exercise and low caloric intake puts significant stress on the young athlete's body. In response to this stress, the hypothalamus starts to stimulate the ovaries less.

Eventually, ovulation stops, along with the athlete's periods. Over time, her ovaries slow down hormone production and her estrogen level drops, which causes bone loss and other negative health effects.

The female athlete triad is common among young female ballet dancers, especially teenagers who are training hard while trying to maintain a low body weight due to the pressure they sometimes face to be thin.

Change in Your Flow

Don't be alarmed if you notice that your periods become a bit lighter once you start regularly exercising. The same hormonal changes that can stop your periods altogether can also lead to a lighter flow.

Additionally, regular exercise can lead to weight loss, which may also lead to a lighter flow.

Body fat (adipose tissue) actually produces a type of estrogen. Excess estrogen in your body can cause the lining of your uterus to build up more than usual during the first half of your cycle. The thicker the lining, the heavier your menstrual flow.

Weight loss therefore decreases the amount of estrogen in your body, which in turn decreases the buildup of your uterine lining that occurs each cycle. A thinner lining means a lighter flow.

Period Pain

There are two distinct types of period pain—known as dysmenorrhea. Exercise might help with the pain, but it depends on what type of dysmenorrhea you have.

Primary Dysmenorrhea

Primary dysmenorrhea is a painful period with no clear cause. It usually starts with your very first period and then the pain comes with each period after that. It often goes away by the time you are in your 20s. It is likely that exercise can help reduce this type of painful period.

The hormonal changes that regular exercise causes may decrease the amount of prostaglandins in the lining of your uterus. Prostaglandins are chemicals that cause your uterine muscles to contract and create cramps. That is why anti-inflammatory pain medications that block prostaglandin production, like Motrin (ibuprofen), treat menstrual cramps best.

In theory, if you can decrease the amount of prostaglandins in your body, you can have less period cramping. That said, more studies are needed to prove that exercise will reduce your cramps this way.

Secondary Dysmenorrhea

Secondary dysmenorrhea is a painful period that results from having an underlying condition. This type of menstrual pain usually develops over time and may not start until your 20s or even later. 

Two common conditions that cause this type of period pain are uterine fibroids and adenomyosis, in which the inner lining of the uterus grows into the uterine muscles.

If you have secondary dysmenorrhea, exercise may help ease the pain during your periods. That's because, even if you have an underlying condition, exercise can still reduce the amount of prostaglandins in your body.

On the other hand, there is a chance that exercise may make your periods more painful, especially if you have uterine fibroids. These benign tumors grow on the smooth muscle in the wall of your uterus, and in order for them to do that, blood vessels must form to bring them blood and nutrients.

When you exercise, your body directs blood flow to your heart, lungs, and muscles and away from structures that aren't involved in exercise. Normally, your uterus adapts to this without any problem. But if you have fibroids, less blood will also flow to them when you exercise.

This causes a condition known as ischemia, which is similar to what happens in heart muscle during a heart attack. When a muscle becomes ischemic, you feel it as pain.

Summary

Intense exercise can cause changes in the hormones responsible for your menstrual cycle. It can cause you to have breakthrough bleeding when you are not on your period, lighter periods than you normally have, and sometimes, no period at all.

Exercise may help ease period pain in some people, since it reduces the amount of prostaglandins in the body, which are responsible for painful period cramps. However, people with certain conditions, like uterine fibroids, may feel more pain when they exercise.

A Word From Verywell

For the most part, some breakthrough bleeding or an occasional missed period is not a big concern if you have just started exercising, have suddenly increased the intensity of your exercise, or have just lost a lot of weight. But if you have seen a change in your cycle that continues for two to three months in a row, you should discuss it with your doctor.