Gym junkies set on sexy pecs and biceps might pay for it in posture problems later in their lives.

Brian K. Farr, clinical associate professor in the Department of Kinesiology and Health Education, said that repeated exercise with the same muscles creates an imbalance where one part of body is strong, and the opposing side is weak. For example, bench pressing creates strength in the biceps and chest, while the back muscles remain inactive.

“The habit of doing bench press, bicep curls and shoulder exercises … things that are ‘in front’ that you can pose and look good … without a balance in the back muscles is going to lead to bad posture,” Farr said.

This is bad news for serial bench pressers, because the same muscles they’re working on to flex are the ones keeping them hunched over at their desks.

When someone hunches over all day and works just on chest and arms, they can develop an increased curve in their spine, Farr said. Over time, the curve in the spine can worsen, leading to upper crossed syndrome, an imbalance of weak and strong muscles in the neck and shoulders that creates a slouched posture, headaches and back pain, according to Medical News Today.

“There are some potential long term consequences after developing that upper crossed syndrome,” Farr said. “When you are stuck in this forward position, you put undue pressure on your spine. You aren’t moving or being aligned in the right way, so there is stress on tissues that shouldn’t have stress.”

If you’re not trying to break the bench press world record, you should strive for balance, Farr said.

“Most people lift to look good and be healthy,” Farr said. “If that is your goal, then balance is very important. You have to be equal. Work out the opposite muscle group as much as you work out the ‘posing muscles.’”

When we sit, we deactivate certain muscles and activate others, which is why a workout that challenges many muscle groups is important, according to Health magazine.

“Sitting all day creates a tug of war between opposing muscle groups, except only one side is tugging,” Farr added.

So, in order to keep yourself looking like a college student and not hunched over like your grandparents, balance your body at the gym. After all, good posture can be sexy.

Editor's note: Gym Smarts is a recurring column that discusses the science behind popular workout and wellness topics. Information in this column cannot replace legitimate medical advice. If you think you have serious muscular, postural problems or an injury, be sure to consult a physical trainer or certified expert.