Well, this should shave some time off of your gym routine: Stretching before working out can make your muscles feel weak and unsteady, according to a new study published in the Journal of Strength and Conditioning Research.
Researchers asked 17 men to complete squat exercises during two gym sessions. Prior to the first session, all of the participants performed an active dynamic warm-up routine that involved having participants mimic the motions of the upcoming exercises, but at a slower pace. Before the second session, they completed passive static stretching exercises, which consisted of three sets of 10-second stretches for participants’ calves, hamstrings, and quadriceps. After the participants exercised, researchers asked them, “How stable and balanced did you feel during that lift?” The study found that participants felt 23 percent less stable and balanced after they completed the passive static stretching than they did after doing the active dynamic warm-up.
Why? Stretching causes tendons to loosen up, leaving your muscles less firm, says study author Jeffrey Gergley, an associate professor of kinesiology at Stephen F. Austin State University. When that happens, the muscles have less force to lift weights.
You can do dynamic warm-ups before any type of workout—not just strength training. “In any type of exercise movement, there’s a motor pattern associated with it,” says Sabrena Merrill, an education consultant and exercise physiologist for the American Council on Exercise. Both Gergley and Merrill agreed that active dynamic warm-ups prepare your body to perform better because you’re getting your body used to the motions of the more intense workout. Merrill says this kind of warm-up literally warms your body more than stretching, and that in turn allows your muscles to adapt to an exercise quickly and more efficiently.
So is stretching ever a good thing? While stretching before your body heats up can tear muscle fibers, says Gergley, limbering up after your workout won’t do any damage. Loosening up post-exercise can relax you and help bring your muscles back to their resting state, says Merrill.
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