How Bad Is It Really to Bounce When You Stretch?

Stretching helps improve flexibility and prevent injury and tightness, but when you're in the thick of a challenging stretch, you're bound to get a little antsy — if not downright uncomfortable. That's when the temptation to bounce, or rapidly pull in and out of a stretch, may very well arise.

Known as ballistic stretching, this form of dynamic stretching first became popular in the 1970s with aerobic dance workouts, says Alena Anthony, a certified strength and conditioning specialist (CSCS) and associate director of fitness programs at Syracuse University's Barnes Center at The Arch.

At the time, the belief was that bouncing while holding a stretch would increase your range of motion, Anthony says. But today, health experts generally discourage ballistic stretching because the rapid movements and bouncing can increase the risk of injury, according to a February 2012 article in the ​International Journal of Sports Physical Therapy​.

So how bad is it really to bounce when you stretch, and what makes ballistic stretching less effective than other forms? Here's what you need to know about ballistic stretching.

Ballistic stretching, which calls for bouncing in and out of a stretch, isn't going to improve your flexibility to the same extent that other forms of stretching will.

According to the American College of Sports Medicine, static, dynamic and proprioceptive neuromuscular facilitation (PNF) stretches are much more effective for improving flexibility. (FYI, flexibility is measured by how much the muscles and tendons that surround a joint or joints are able to extend or lengthen.)

Static — or passive — stretching is probably the most common type of stretching, and it simply entails holding a position that allows your muscles and connective tissues to lengthen (think: a seated forward fold in yoga or standing and trying to touch your toes).

Dynamic stretching, on the other hand, is active and involves movement, like leg pendulums or arm circles. Finally, PNF involves contracting and relaxing the muscle and is often done with a partner, like a partner hamstring stretch.

Although dynamic and static stretching are safer and more effective, Geoffrey Dreher, DO, assistant professor of orthopedics at Johns Hopkins University School of Medicine, says recent research shows that ballistic stretching may have some benefits in specific instances.

For example, a July 2016 study in the ​Scandinavian Journal of Medicine and Science in Sports​ suggests that ballistic stretching can, indeed, help improve joint range of motion, but static and dynamic stretching offer the same improvements without the risks associated with ballistic stretching.

Anthony also says that ballistic stretching can encourage blood flow, which may make it appealing to athletes hoping to warm up certain muscle groups before exercising or playing a game. But, again, dynamic stretching can accomplish the same goal more safely.

While dynamic stretching may resemble ballistic stretching in the sense that it also requires movement, Lauren Shroyer, a certified athletic trainer (ATC) and senior director of product development at the American Council on Exercise, explains that dynamic stretching has smoother transitions between movements and doesn't require you to move as aggressively or as quickly as ballistic stretching does — and this is what can get you in trouble.

Dr. Dreher says that because your movements are faster and more varied when stretching ballistically than they are in other types of stretching, you have less control over how far you can go into that position. As a result, you're more likely to push past your body's safe range of motion and get hurt.

Anthony notes that ballistic stretching actually overrides the body's failsafe against overstretching, known as the Golgi tendon organs. Embedded within tendons and connected to muscle fibers, these force sensors communicate with the brain during stretching, noting the amount of tension in the muscle that's being stretched.

When that tension exceeds a comfortable range of motion (which, Anthony says, will differ for everyone depending on their flexibility and comfort level with stretching), they'll alert the brain, effectively stopping the stretch and relaxing the muscle.

During slow, controlled stretching, Golgi tendon organs have plenty of time to sense when you're exceeding your normal range of motion, issue that alert signal and stop the stretch, Anthony says. During ballistic stretching, however, your movements are continuous, meaning your muscles don't have a chance to relax — and the Golgi tendon organs can't react in time to prevent overstretching.

When you exceed your body's range of motion, you could end up straining a muscle, if not injuring your ligaments and other soft tissues as well, Dr. Dreher says. For example, bouncing in and out of a butterfly stretch could strain the adductor muscles (the muscles that bring your thighs together) in your groin, he says. And stretching your hamstrings ballistically could end up straining your lower back.

It's unpleasant enough to deal with a strained muscle after stretching ballistically once, but doing it on a regular basis can have longer-lasting effects, too. Over time, repeatedly straining your muscles and jerking them into overextended stretches places an abnormal amount of stress on them, which may lead to overuse injuries, Anthony says.

And, she adds, that stress can also contribute to inflammation in the tendons, which could result in tendonitis, or chronic pain and discomfort. Bouncing may even lead to tighter, less flexible muscles overall, according to the Mayo Clinic.

While athletes might benefit from ballistic stretching as a means of stimulating blood flow and warming up before playing their particular sport, the average active person is better off practicing other forms of stretching.

If you want specific alternatives to ballistic stretching, Shroyer recommends stretching statically on a daily basis after working out or during recovery days. She says to hold static stretches for at least 30 seconds in order to see more long-term, permanent gains in flexibility. Shroyer adds that dynamic stretching, on the other hand, is a great pre-workout or pre-sport routine to prepare your body for exercise.

In short, Anthony says she'd never recommend ballistic stretching — there are just better, less risky options out there.