We know that exercise keeps the body young, but what about the skin?

Skin care and exercise have a complicated relationship. For every dermatologist out there who will tell you that sweat is amazing for your skin, there’s another who will caution you about the impending pimple risk it poses. So the real answer to the question of whether that gym sesh will help or hurt your complexion is, well, both.

Sweat does a lot of different things for skin: some of it good, some of it bad, and (if my own sweaty post-gym selfies are to be believed), some of it downright ugly. For the full 411 on how skin care and exercise relate, we had the pros break down all of the different ways your workout can effect your complexion.

Skin care and exercise: the good

Brightening: When you exercise, your blood vessels expand, and more blood and oxygen flow to the surface of your skin. This, says board-certified dermatologist Marisa Garshik, MD, gives the skin a brighter appearance. “At its most fundamental level, sweating occurs to protect us from overheating, which as a result, translates into a brightened glow rather than an intense flushed appearance to the skin,” she explains (though, let’s be real: some of us, self included, still flush). But, if you’ve ever looked in the mirror after a workout and thought: “Damn, girl!” consider that the explanation you’ve been looking for.

Protecting: While sweat certainly can bring on breakouts, it also offers some protective measures, too—no matter what type of skin you’ve got. According to Dr. Garshick, it acts as a barrier on the skin, and releases an antimicrobial peptide called dermicidin that can help to fight against bacteria and prevent infection. It also helps to promote oil production to keep skin from drying out.

Skin care and exercise: the bad

Chafing: Even if you aren’t logging 26.2 marathon miles, skin chafing during a workout is definitely still a thing (though thankfully, unlike with marathon runners, your nipples will likely be spared). According to Dr. Garshick, this happens because of “a combination of friction and moisture build up often occurring in folds of the skin or in areas where the skin is in close contact.” To prevent it, use a strong antiperspirant or anti-chafing stick before you exercise, and be sure to dry any folds in your skin after you’re done. Another pro tip? “It can also help to create a barrier to prevent the skin from getting irritated so it can often help to apply a layer of thicker moisturizing ointment such as Vaseline or Aquaphor to the area where chafing may occur both to prevent it and treat it,” she says. Wearing sweat-wicking clothing can also help.

Acne or clogged pores: When you leave sweat on your skin for too long, it can “attract bacteria and clog pores,” says Dr. Garshick, so if you’re prone to acne you should be rinsing your face immediately after your workout. Use a gentle cleanser to eliminate dirt and sweat without causing irritation, but be sure not to over wash or exfoliate which can wind up doing even more damage. If you do wind up with any exercise-induced acne, particularly on your back and chest, Dr. Garshick recommends a salicylic acid spray such as Glytone Acne Treatment Spray ($42) as a helpful remedy. Speaking of acne, here’s how to nix it:

Irritation: Clogged pores aren’t the only thing you need to worry about: Sweat is packed with salt, which can be drying and irritating. “It’s important to not let the sweat sit on the skin for too long as it can become aggravating, particularly for those with sensitive skin” says Dr. Garshick, who suggests a lightweight body cleanser like Dove Instant Foaming Body Wash ($6) to help you get clean.

This magic skin-care stick actually activates while you sweat. Pretty cool, huh? And these are the best post-workout skin-care products worth keeping in yor beauty bag. u