How Your Period Messes With Your Workouts & What to Do About It

You're not alone if you've ever dragged yourself through a workout wondering: Why does this feel infinitely harder than usual. You're also not alone if you find yourself thinking this every month. Yep, we know where this is headed ...

Could your menstrual cycle be affecting your workouts?

"There's a lack of consistent data regarding whether these hormonal shifts directly affect exercise, but there are certainly things we can anticipate when we consider what's known about female physiology," says Dr. Megan Cannon, an OB-GYN at Houston Methodist.

For instance, we know female physiology is different from male physiology in key areas, ranging from body composition and muscle morphology to appetite control and iron metabolism.

"These differences can influence how your body works and uses energy," adds Dr. Cannon. "And hormonal shifts during your cycle can have downstream effects on several of these factors, further complicating the issue."

While the science is still evolving, Dr. Cannon adds that we know enough to help you work with your cycle rather than against it.

Why am I so tired on my period?

Feeling wiped out during your period isn't just about cramps or mood changes. It's also about energy availability.

"Energy is crucial for every physiological process in the body, including exercise performance and recovery," says Dr. Cannon. "In females, it's also needed to support reproductive functions, which adds another layer of complexity."

If you have particularly heavy periods, dips in iron levels can affect energy levels even more, leading to fatigue. (Related: 5 Causes of Iron Deficiency)

All of which is to say, your body is multitasking hard during menstruation.

But that's not the only time. Other menstrual phases are also physiologically demanding, each bringing its own hormonal shifts that affect energy, mood and more.

(Related: Menstrual Cramps: 5 Tips for Getting Relief From Period Pain)

The four phases of the menstrual cycle, explained

We tend to think about menstruation the most — for obvious reasons, of course — but your cycle isn't just about your period, or just your uterus. It's a full-body hormonal rollercoaster that spans roughly 28 days, though it can range anywhere from 21 to 35 days depending on the person.

The point of the cycle is to prepare your body for a potential pregnancy, which means your hormones (namely estrogen and progesterone) are constantly shifting to support ovulation, fertilization and — if that doesn't happen — the process of resetting the cycle so it can happen all over again.

Here's a quick breakdown of the four phases of the menstrual cycle:

• Menstrual phase (days 1–5): The uterine lining sheds, and estrogen and progesterone levels are at their lowest. Fatigue and discomfort are common.
• Follicular phase (days 6–14): Estrogen begins to rise, prepping the body for ovulation. Energy and mood often improve.
• Ovulation (around day 14): Estrogen peaks, and the body releases an egg. You may feel stronger and more energized.
• Luteal phase (days 15–28): Progesterone rises and estrogen drops. This can lead to bloating, fatigue and sleep disturbances.

What shifts in estrogen and progesterone levels may mean for your workouts

As Dr. Cannon mentioned, there's a lack of consistent data on the subject. But here's what we do know:

Estrogen peaks in the late follicular to mid-luteal phase (around days 12–21)

This can reduce glycogen stores (your muscles' fuel), increase water retention and dull hunger cues. "You might not feel hungry, but your body still needs fuel," says Dr. Cannon. "Be sure you're eating well-balanced meals throughout the day and fueling for workouts."

Progesterone is highest in the mid-luteal phase (around days 19-24)

This ramps up your metabolic rate and reroutes nutrients to the uterus in case of pregnancy. This can reduce glucose uptake and muscle synthesis, making exercise and recovery harder. "Sleep quality also tends to dip during this phase, which can impair muscle repair and lead to reduced energy levels," explains Dr. Cannon.

How to adjust your workout regimen to your cycle

Follicular phase tips:

• Carb-load before workouts to boost energy
• Don't skip your post-exercise meal — it helps with exercise recovery
• Consider iron supplements, especially if you have heavy periods

Luteal phase tips:

• Eat a pre-workout snack 3–4 hours before exercising (aim for 30g of carbs for high intensity, 30–60g if your workout lasts over an hour)
• Increase daily protein intake by about 12%
• Creatine supplementation may help offset reduced muscle synthesis
• Use a carb-electrolyte drink during endurance workouts in hot weather

What about perimenopause and menopause?

Even if you're not there yet, it's good to know what's coming. In perimenopause, progesterone levels drop, which can lead to decreased lean muscle mass, lower bone density and reduced energy. "Protein synthesis in muscle also drops, which means recovery takes longer," says Dr. Cannon.

(Related: When Does Menopause Usually Start?)

After menopause, resistance training becomes even more important. "Strength training helps counteract the natural decline in muscle mass and supports metabolic health," Dr. Cannon explains. Protein supplements can also help maintain muscle and support recovery.