Side Effect #4: Heartburn
Common sense tells you that guzzling a 20-ounce bottle of water isn't a great idea before you do decline chest presses. "We all have a little physiological reflux, which is normal," says Higgins. And even those who don’t usually have a problem with indigestion may experience some reflux or heartburn at the gym. Higgins warns that taking ibuprofen on an empty stomach may make symptoms worse, as will eating or drinking too close to your workout.
How to reduce your risk: Try taking small sips of water during your workout instead of big gulps, and wait an hour or two after you eat before working out. If the heartburn is accompanied by shortness of breath and/or chest pain, see a doctor immediately, as these may be symptoms of a heart attack.
Side Effect #5: Side Stitch
Typically seen in runners, this stabbing pain in the side can come out of nowhere and literally take the wind out of your sails. It's known as exercise-related transient abdominal pain (ETAP) in the medical world and it’s common, says Higgins. "A new exercise program or increasing the intensity of your current program seems to increase ETAP." Several theories about ETAP exist, but posture appears to play a role, according to a 2010 study published in the Journal of Science Medicine and Sport. Slouching or running hunched over may affect nerves that run from the upper back to the abdomen, resulting in pain.
How to reduce your risk: Run using good posture and try adopting a rhythmic breathing pattern, which involves coordinating your breathing with your foot strikes, says Higgins. ETAP typically reduces with time and as overall fitness improves.