Portrait of Nathaniel Scharping
Nathaniel Scharping
Portrait of Lauren A Koenig
Lauren A Koenig, PhD

You’re weightlifting at the gym and heading out on runs twice a week — you’re putting in the effort, so you definitely want to see some payoff. While there’s more than one factor that affects how your body responds to exercise, it’s natural to wonder whether your hormones might be affecting your fitness. Could your be affecting the impact of your workouts?

The sex hormones in do affect on how our muscles and cardiovascular systems work,1 so it’s likely that they impact how our bodies respond to exercise. But, like a lot of things with hormonal birth control, the effects aren’t always straightforward, and the studies that do exist sometimes say different things.

Current scientific consensus is that likely has a small, but negative effect on muscle growth and recovery after a workout.2 But what that impact looks like can depend on the type of you’re on, as well as how that interacts with your own unique biology. Confusing things further, different formulations of contain different types of s — like norethindrone, levonogesterel, or drospirenone — which can affect the body differently. That means there’s no one-size-fits-all answer.

Your choice of likely won’t make a huge difference to your physical fitness.

But unless you’re an athlete who’s super focused on pushing the envelope, your choice of likely won’t make a huge difference to your physical fitness. Let’s walk through what we do, and don’t, know about working out on .

How the Hormones in Affect Your Body

All forms of hormonal contain a synthetic version of the sex called .3 Some contain as well.4 These hormones work to stop ovulation, or the release of an egg from your , and also make it harder for sperm to swim.5

But and play a lot of other roles in our bodies, too. The sex hormones influence mood, bone formation, neurological health, acne, cardiovascular health, and more.5-6 That’s why hormonal contraceptives can come with side effects — both good and bad ones.

Most importantly when it comes to exercise, and impact how both muscles and the cardiovascular system function. increases blood flow to the heart and muscles,1 and can increase cardiac output. It also likely plays a role in helping to maintain muscles. Some studies also show could increase the synthesis of muscle protein.8


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Working Out On

A number of studies have looked into how various kinds of affect exercise performance. But results are mixed, which makes drawing conclusions challenging, especially when different studies look at different formulations of . One consistent finding is that the sex hormones in affect various kinds of exercise differently, like lifting weights versus going for a run. And does also seem to change how your body recovers after exercise, which is a big factor in how your body adapts to training.

Birth Control and Muscle Growth

In one small study, scientists had 28 people — half on , half not on — do leg exercises for ten weeks to see if there was a link between and muscle growth. Those using gained more muscle mass than those not on .9 But another study with a similar setup saw the opposite effect after ten weeks of exercise: those using saw smaller gains in muscle mass after the workout program.10 Researchers noted that the type of also seemed to play a role in muscle building: the more androgenic, or “male-like” s, like levonorgestrel and norithendrone,11 were linked to even smaller gains in muscle mass compared to s like desogestrel and norgestimate.

The type of also seemed to play a role in muscle building.

There’s an additional caveat to both of those studies: While they found that affected gains in muscle mass after working out, both studies reported that there were no changes in muscle strength between study groups. In other words, the people on ended up just as strong as the people not taking .

Birth Control and Endurance

Some studies show that cardiorespiratory performance (i.e., how the heart and lungs deliver oxygen to your muscles during physical activity) might be slightly impaired by ,12 and that maximum oxygen consumption (VO2 max), which shows how hard your body is working while exercising, might also be a bit worse.13

Another study that analyzed resting heart rate and heart rate variability in ~4,600 people as measured by a fitness tracker found that people taking with also might not recover quite as well after a workout, though again, the effect was small.14 People on progestin-only contraceptives recovered about as well as those not taking hormonal contraceptives.

Where does all of this leave us?

The most comprehensive review study of and exercise to date says might result in slightly inferior exercise performance on average when compared to naturally menstruating women” (emphasis added). So, there may be a small negative effect, but only maybe sometimes.2

But the review also notes that most of the studies the researchers looked at were low quality and quite small (studies included just 10 people on average). There was also a lot of variation between studies when it came to the effects of on exercise performance, and the review lumped together studies on both muscular strength and endurance.2

Overall, the author’s conclusion was that might have a slightly negative impact on exercise performance. But the effect was so small that it was really only an issue for competitive or professional athletes who have reason to track and monitor even the tiniest gains in fitness. Additionally, there was so much variability in people’s responses to exercise on that it was hard to make generalized recommendations.2

What Do I Need to Know About and Exercise?

Based on the best evidence we have, may have a small, but negative effect on physical performance. But those findings come with considerable caveats, and are from small, lower quality studies. Moreover, some of these studies contradict each other, and scientists say we need more research. The medical research that favors men over women in research is definitely to blame here, and while that’s beginning to change, it might be some time before we see truly equitable studies.

Being on has some other benefits for athletes and physically active people.

If you’re just trying to get more fit or train for your local 10K, there’s no evidence right now that your is going to make or break your goals. But you should also remember that being on has some other benefits for athletes and physically active people. For example, skipping your period can be one less thing to worry about when you need to perform at your best.

Ultimately, the same advice applies to making decisions about as it does to working out: You should listen to your body and figure out what works for you. Different people respond to the same kind of in different ways. If you feel like your is dragging you down, there are many more options to choose from.

Want to read more about finding the right for your body? Get started with The Birth Control Test

  1. Mattu, Anmol T., et al. “Menstrual and oral contraceptive cycle phases do not affect submaximal and maximal exercise responses.” Scandinavian Journal of Medicine & Science in Sports 30.3 (2020): 472-484.
  2. Elliott-Sale, Kirsty J., et al. “The effects of oral contraceptives on exercise performance in women: a systematic review and meta-analysis.” Sports Medicine 50.10 (2020): 1785-1812.
  3. CDC. “Contraception.” CDC.gov (2023 Mar 27): Accessed 2023 Apr 28.
  4. CDC. “Combined Hormonal Contraceptives.” CDC.gov (2023 Mar 27): Accessed 2023 Apr 28.
  5. Cable, Jessie K., and Michael H. Grider. “Physiology, Progesterone.StatPearls [Internet] (2022 May 08): Accessed 2023 Apr 28.
  6. Delgado, Benjamin J., and Wilfredo Lopez-Ojeda. “Estrogen.” StatPearls [Internet]. (2022 Jun 28): Accessed 2023 Apr 28.
  7. Haizlip, K. M., B. C. Harrison, and L. A. Leinwand. “Sex-based differences in skeletal muscle kinetics and fiber-type composition.” Physiology 30.1 (2015): 30-39.
  8. Smith, Gordon I., et al. “Testosterone and progesterone, but not estradiol, stimulate muscle protein synthesis in postmenopausal women.” The Journal of Clinical Endocrinology & Metabolism 99.1 (2014): 256-265.
  9. Dalgaard, Line B., et al. “Influence of oral contraceptive use on adaptations to resistance training.” Frontiers in Physiology 10 (2019): 824.
  10. Riechman, Steven E., and Chang Woock Lee. “Oral contraceptive use impairs muscle gains in young women.” Journal of Strength and Conditioning Research 36.11 (2022): 3074-3080.
  11. Stanczyk, Frank Z. “Structure–function relationships, pharmacokinetics, and potency of orally and parenterally administered Progestogens.” Treatment of the Postmenopausal Woman. Academic Press, 2007. 779-798.
  12. Barba-Moreno, Laura, et al. “Cardiorespiratory responses to endurance exercise over the menstrual cycle and with oral contraceptive use.” Journal of Strength and Conditioning Research 36.2 (2022): 392-399.
  13. Lebrun, C. M., et al. “Decreased maximal aerobic capacity with use of a triphasic oral contraceptive in highly active women: a randomised controlled trial.” British Journal of Sports Medicine 37.4 (2003): 315-320.
  14. Sims, Stacy T., Laura Ware, and Emily R. Capodilupo. “Patterns of endogenous and exogenous ovarian hormone modulation on recovery metrics across the menstrual cycle.” BMJ Open Sport & Exercise Medicine 7.3 (2021): e001047.