When it comes to exercise, weight loss and strength gains aren’t the only possible side effects. Every once in a while, a case of itchy legs, numb feet, sleepy butt, or that dreaded runners’ stomach can rear its ugly head. “Working out isn’t always smooth sailing,” says Aaron V. Mares, M.D., assistant professor of sports medicine at the University of Pittsburgh Medical Center. “Along the way, while logging miles, anyone from newbies to athletes can become susceptible to certain discomforts.” Here are four symptoms you might encounter, plus their  possible causes and how to alleviate each one.

1. Itchy Skin During Cardio
What It Feels Like: An itchy sensation on your arms, legs, or even across your entire body.

What it Might Be: A harmless side effect of expanding blood vessels. When your heart rate and blood flow increase during exercise, your cells release a compound called histamine. This causes your capillaries to dilate, which can trigger an itchy sensation.

How to Alleviate It: “Histamine release tends to be more common in beginners,” says Mares. “Hopefully, as exercise progresses, it goes away.” If the itching persists, make sure to rule out other often-overlooked causes. “People tend to forget simple things [that can also cause itching]: detergents, material irritants, and food,” says Mares. All culprits ruled out and legs still itchy? Consult your doctor.

2. Feet Falling Asleep On The Elliptical
What It Feels Like: Numbness in your feet.

What it Might Be: The motion of the elliptical keeps your feet more grounded; that fixed position could cause sleepy feet.

How To Alleviate It: Check your sneakers. While you might not be able to do a whole lot about foot positioning or form, you can do your best to pad the situation—literally. “Limit compression of the plantar nerves by making sure you’re wearing proper-fitting and cushioned footwear,” says Mares. When standing, there should be about a half-inch space from the end of your longest toe to the edge of the shoe. It should also be cushioned and flexible enough for your foot to move naturally.

3. Numb Butt While Rowing
What It Feels Like: You can’t feel your rear after a few pulls.

What it Might Be: “A lack of feeling in your posterior is usually due to compression of the sciatic nerve and the nerves in the lower back/buttock region,” says Mares.

How To Alleviate It: “If you have a lower-back issue that’s affecting the lower lumbar sacral nerves, and rowing is irritating that, try limiting how much you bend forward,” says Mares. If your back is healthy, consider cushioned bike shorts. “It might be that you don’t have enough padding,” says Mares.

4. Runners’ Stomach
What It Feels Like: A variety of digestive symptoms including nausea, vomiting, stomach pain, and diarrhea.

What it Might Be: “Sometimes it’s just nerves, like [when you’re] getting ready to run a marathon,” says Mares. “Sometimes it’s related to food and diet, so when and what you eat around the time you exercise can play a role.” Medication can also act as a trigger. “Taking anti inflammatories can irritate the stomach lining,” says Mares. “As can some supplements.” Avoid taking them before you exercise.

How To Alleviate It: Eat smart. “Take in something that’s high in carbs and low in fiber and fat before your run,” says Katherine Hopkins, RD, a sports dietitian at the University of Pittsburgh. “Rather than having a bowl of bran with full fat yogurt, have some pancakes with a little bit of syrup and some scrambled eggs—something that will digest quickly and won’t cause any disruption in terms of the jarring activity you’re doing.” Not a breakfast person? Fuel with a fruit smoothie; drinks can sometimes go down easier.