9 Ways Your Body & Mind Change When You Get More Exercise

Including how it affects your sleep.

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Why do I poop after working out? Weird things that happen when you exercise more often.

You may be one of those people who genuinely enjoys getting a workout, someone who schedules their cardio strictly for the social aspects, or a person who avoids exercise as much as humanly possible. But no matter where you stand when it comes to enthusiasm for exercise, you probably know that exercise changes your body, both in the short-term and long-term. We know this — but what you may not know is why these changes happen when we start exercising more.

Lifting weights tends to make your muscles grow, and exercising regularly can affect everything from your cardio health to your mood. But knowing why exercise affects our bodies and brains the way it does is different than simply observing the changes — and understanding how exercise changes you might give you some interesting insight to your routines, as well.

If you've recently started working out more than usual, you might want know what's going on in your body when all the weird side effects of moving more often start to become noticeable. It’s completely normal, of course, to go through a transition period as you start to add exercise to your routine, says Michael Hamlin, NSCA, CSCS, a certified personal trainer and founder of Everflex Fitness.

“This is because your body is adapting to the new physical demands that you’re placing on it,” he tells Bustle, and it usually includes things like soreness, energy fluctuations, and other “growing pains.” But there’s also a whole list of lesser-known side effects that are worth knowing about, too. Keep scrolling to see the nine weird things exercising more does to your body, so you know what to expect.

1. You’ll Be Surprisingly Sore


While you’ll probably expect to feel a bit sore as you get more exercise, Hamlin says it’s not uncommon to feel incredibly sore. “I've had clients mention they can barely get up the stairs after a leg day or that they have trouble turning the steering wheel after a chest day,” he says. “But it's all part of the process when you get started.”

This type of soreness is likely due to the micro tears in your muscles that occur as your body builds strength, Hamlin explains, but it could also be a sign of delayed onset muscle soreness, or DOMS, which is a condition that happens when you push yourself a little too hard during a workout.

2. You Might Feel Achy For Weeks


“The length of time it takes your body to adjust to your new workout routine can vary depending on factors such as your fitness level, the intensity of your workouts, and how consistent you are with your exercise routine,” Hamlin says. “Generally, it can take a few weeks to a few months for your body to fully adapt to a new workout routine.”

To speed up the process, he suggests stretching, taking rest days, and staying as consistent as possible. Once you start working out on a regular basis — which amounts to two to three times per week, Hamlin says — your soreness will start to fade away.

3. You’ll Poop More Often


Go on a long walk, or shimmy your way through a dance cardio class, and you may have to trot off to the bathroom soon after. That’s because exercise really does make you poop. “The more exercise we do the more the body moves food through our digestive system,” Hamlin says, pointing to a 2011 study that looked at the bathroom habits of elite athletes.

These athletes went from pooping 1.3 times a day during their rest weeks to 1.5 times a day during training weeks, which is a noticeable uptick in trips to the bathroom. But even if you aren’t an elite athlete, adding more movement to your weekly routine will get things, um, moving. “The bottom line is being sedentary causes the digestive system to slow down, creating harder and less frequent bowel movements,” Hamlin says. “The more exercise we do, we increase bowel frequency.”

This is especially true if you take in more water to replace all your lost sweat, as an increase in hydration increases bowel movements, too. And that’s a good thing. “Your body thrives on water, so make sure you’re increasing your hydrating liquids to help replenish your body,” says Chloe Puff, a fitness coach and ACE-certified trainer.

4. You Might Feel Horny


During and after exercise, your blood flow increases — and it increases everywhere. Consequently, all that pumping blood allows for your erectile tissue down below (which we all have, FYI) to fill with blood, which may put you in the mood. Good circulation plays a huge role in sexual arousal, and since regular exercise increases circulation, it also increases sex drive. According to a 2018 study, even small bouts of exercise can boost your sexual functioning.

5. You Might Get “Acne Mechanica”


Notice more pimples on your face or acne across your chest or back after working out? This is yet another side effect of a new fitness routine, especially if you sweat a lot in fitted workout clothes. “Acne is more likely to occur when there is friction on your skin from sweating while wearing tight clothing, headbands, or hats,” Hamlin says. “This is called acne mechanica.”

Basically, when your tight sports bra or workout shirt rubs against your skin, it pushes sweat into your pores, which then become clogged and inflamed. To minimize your risk of exercise-related breakouts, Hamlin recommends wearing looser workout gear and showering ASAP post-exercise.

6. You’ll Need To Sleep More


Get into an exercise groove and you may notice that your sleep habits start to change. “Typically, sleep will be improved in quality and duration from exercise,” Hamlin says. “Putting your body through challenging movement will increase the need for recovery, which will help give you a deeper and longer night's rest.”

7. You May Struggle To Fall Asleep


On the flip side, a 2019 study found that doing a vigorous workout less than an hour before bed kept participants awake later into the night. “While working out may relax some people, doing a high-impact workout before bed can actually get your brain fired up and cortisol flowing, which may make it harder to fall asleep,” Puff tells Bustle.

8. You Might Get Your First Runner’s High


If you don’t work out regularly, you might not buy into the idea of a runner’s high, aka the blissful feeling some people claim to have after a long run. But start exercising more often, and you might just experience one for yourself.

“This is a high that you can get from large amounts of cardio work,” Hamlin says. “You will literally feel high, like everything is right in the world. The music in your headphones sounds better, people around you seem nicer, and the world feels the way it’s supposed to be.”

He notes this post-exercise “high” lasts for about an hour before it tapers off into a pleasant, mellow mood that often lasts all day. “This happens because, after large amounts of cardio, we get a massive endorphin rush,” Hamlin says. “It makes you feel great.”

9. Your Mind Will Feel Sharper


When you exercise, your brain immediately starts to function at a higher level because exercise causes increased blood flow to the brain. This is why exercise helps you feel more alert and focused, both during and after our workouts.

Studies have also found a connection between increased exercise and improved mental health. It’s why even the gentlest of workouts, like a slow walk, are recommended as a mood-booster. Add it to the list of weird and wonderful ways your workout can impact your body and mind.

Studies referenced:

Chung, BD. (1999). Effect of increased fluid intake on stool output in normal healthy volunteers. J Clin Gastroenterol. doi: 10.1097/00004836-199901000-00006.

Dolezal, BA. (2017). Interrelationship between Sleep and Exercise: A Systematic Review. Adv Prev Med. doi: 10.1155/2017/1364387.

Gao, R. (2019). Exercise therapy in patients with constipation: a systematic review and meta-analysis of randomized controlled trials. Scand J Gastroenterol. doi: 10.1080/00365521.2019.1568544.

Hicks, SD. (2019). The Transcriptional Signature of a Runner's High. Med Sci Sports Exerc. doi: 10.1249/MSS.0000000000001865.

Hillman, CH. (2008). Be smart, exercise your heart: exercise effects on brain and cognition. Nat Rev Neurosci. doi: 10.1038/nrn2298.

Jiannine, LM. (2018). An investigation of the relationship between physical fitness, self-concept, and sexual functioning. J Educ Health Promot. doi: 10.4103/jehp.jehp_157_17.

Oettlé, GJ. (1991). Effect of moderate exercise on bowel habit. Gut. doi: 10.1136/gut.32.8.941.

Querido, JS. (2007). Regulation of cerebral blood flow during exercise. Sports Med. doi: 10.2165/00007256-200737090-00002.

Strid, H. (2011). Effect of heavy exercise on gastrointestinal transit in endurance athletes. Scandinavian Journal of Gastroenterology. doi: 10.3109/00365521.2011.558110.

Stutz, J. (2019). Effects of Evening Exercise on Sleep in Healthy Participants: A Systematic Review and Meta-Analysis. Sports Med. doi: 10.1007/s40279-018-1015-0.


Michael Hamlin, NSCA, CSCS, certified personal trainer, founder of Everflex Fitness

Chloe Puff, fitness coach, ACE-certified trainer

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