We’ve written before at HuffPost UK about why stretching a “stiff” hip may not actually help your ailing flexors.

We’ve even shared the way-too-common workout mistake that people with lower back pain make.

But what about before your exercise session even starts? Surely stretching before you run, lift, or cycle is a great way to prevent injury?

Well, according to experts like Dr. William Kormos, former editor-in-chief of Harvard Men’s Health Watch, not all stretches may be helpful.

There are multiple types of stretching you can do; static stretching (where you stay still in a stretched position for ten seconds plus) and dynamic stretching (moving as you stretch) are two of the most common kinds.

“Recent expert opinion has moved away from static stretching before activity and toward a gradual and active warm-up period before exercise,” the doctor wrote on Harvard’s site.

“Stretching a healthy muscle before exercise does not prevent injury or soreness,” he added (sorry, what?).

Not only that but some research has found static stretching before sports like sprinting seems to harm performance; one study found that runners had a 3% decrease in performance at 40m after stretching than those who didn’t.

Speaking to health site Cleveland Clinic, doctor of osteopathic medicine Anne Rex seemed to agree that it’s not the best move during warm-up.

“Dynamic stretching mimics the activity or the movement that you’re going to do in whatever sport or activity you’re about to start,” she said.

“It helps rehearse the movement patterns so the muscles tend to get excited a little bit earlier and faster, which can help improve power and increase coordination.”

Meanwhile, static stretching is more of a “relaxation” exercise than a warm-up one, she says; but that “relaxation” can be helpful during cooldown.

If you like a static stretch, include them after your workout rather than before; and, as others have advised, Dr. Rex says you should keep an eye on the time while performing them.

“The longer you stretch, the more there will be a negative impact on performance,” she explained, advising we hold it for “around 15 to 30 seconds, not 60 to 90 seconds.”