Nope, it's not static or dynamic! But it can help improve mobility, and keep you injury-free

By Caitlin Carlson
February 26, 2015
Corbis Images

There's a new kind of stretching in town, and we guarantee you haven't heard of it. For starters, it has a pretty fancy name: Proprioceptive Neuromuscular Facilitation (or PNF for those in the know). And it's a stretching technique that involves a partner and (the good kind of) pain. (Check out The Bring-a-Friend Workout.)

Allow us to explain: PNF is basically a technique where you do a static stretch-but you contract certain muscles while a partner helps hold you in that stretch. For example, you could lie down and have a partner stretch your hamstring to its limit (like in the picture above.) Then, you'd contract that muscle before they'd release your leg and have you do it again, this time stretching your hammie further than the first time. This is repeated for a set number of reps, each time stretching your muscle a bit further. (Dynamic stretching, on the other hand, involves repetitive slow or rapid movements, without holding the stretch in a lengthened position.)

So, why should you recruit a partner and suffer through discomfort? A new study published in the journal Medicine & Science in Sports & Exercise found that PNF can improve range of motion more so than static or isometric stretching. "The intense contractions during PNF reduce the stiffness of the tendon resulting in an increase in range of motion (ROM) and may be a mechanism for PNFs superior efficacy above other stretching modes," says study author Anthony Kay, Ph.D.

And improved ROM can prevent injuries like muscle strains during your sweat sessions. (Check out The Best Ways to Avoid Injury While Training for a Marathon.) Plus, improved mobility could help you go through a bigger range of motion when you do exercises like squats in lunges (AKA you can get lower and get more benefits.)

But, there may soon be a solution to the pain/partner problem: Kay is developing a method that could get you the same perks minus the partner-and the pain. In the meantime, you can try this type of stretching with a friend post-workout, or on a "rest" day two or three times a week, says Kay.