So here’s the scenario: You’re lifting weights only to catch yourself holding your breath. In the moment, you’re so focused on the fundamentals of the movement you’re working on that you forget to breathe. Or perhaps it’s a subconscious strategy to make the workout feel easier, more stable.

As common as it is, holding your breath while strength training is actually anything but beneficial.

Why do we tend to want to hold our breath?

Most of us guilty of this bad habit. But what makes it so tempting? According to exercise physiologist Tom Holland, a Bowflex fitness advisor and the author of Beat The Gym: Personal Trainer Secrets—Without the Personal Trainer Price Tag, people tend to shorten or hold their breath during stressful situations.

“It’s often the result of the numerous physiological processes that occur during our sympathetic nervous system’s fight-or-flight response,” he explains.

While working out may feel like the calmest, most centering part of your day, it still places stress on the body. If it didn’t, you’d never find it difficult to perform another rep, another set. It’s this stress, which people often overlook, that triggers us to hold our breath.

“We often do this unknowingly, which is why fitness instructors and personal trainers will often give the simple cue to ‘just breathe,’” Holland adds.

How does holding your breath affect your strength?

Some of the strongest people in the world are prone to holding their breath while working out—but make no mistake: The practice doesn’t benefit the everyday athlete.

“Powerlifters will often hold their breath to increase intra-abdominal and intra-thoracic pressure, thereby increasing pelvic and spinal stability,” Holland shares. This is often called the Valsalva maneuver. “This can be helpful during heavy, maximal lifts, especially those involving compound exercises such as deadlifts and squats.” But for the vast majority of exercisers (aka anyone not lifting extreme weights), this technique isn’t recommended.

Need proof? In a 2021 study published in the journal Biology of Sport, researchers found that holding your breath during a maximal bench press did not provide any benefit.

Is it bad to hold your breath while lifting weights?

Not only is holding your breath unhelpful, Holland says there are also some not-so-great side effects. Namely, “an increase in blood pressure, fainting, hernias, and even heart attacks, depending upon your current health status and pre-existing conditions,” he warns.

This is why it’s important to constantly remind yourself to breathe while lifting weights. Generally speaking, personal trainers will instruct you to inhale during the easier part and exhale on the harder part. More scientifically, Hollands says “to inhale during the ‘down’ or eccentric phase of an exercise and exhale during the ‘up’ or concentric phase.”

Consider this example: “During a push-up, you would inhale while lowering your body towards the floor and then exhale while pushing back up to the starting position,” Holland says.

While it may take some practice to align your breathing with your movements, Holland says the most important thing is to do, in fact, keep breathing. “Avoid holding your breath and breathe naturally throughout your movements,” he encourages.