Your hip flexors and quads ache, a dull pain that you’ve probably felt before, especially after training. You think you know how to deal with it. You foam roll, you do some stretches, but this only sort of fixes the achiness. That’s because the problem isn’t just about your muscles.

The real culprit: You’ve been neglecting your fascia, the fibrous tissue that was once thought to simply encase your muscles. More recently, it’s been shown to play a key role in how your body moves—and why it occasionally aches. The sooner you learn to take care of this oft-overlooked tissue, the faster you’ll bounce back from that painful hip flexor and other kinds of soreness—and the bouncier you’ll be during any activity, whether that’s running, lifting, doing errands, or goofing off with your kids.

For years, fascia was viewed as something to be kneaded and leveled (hence that roller), mostly to prevent injury and to warm up. But that’s only part of the story, says Bill Parisi, C.S.C.S., author of the book Fascia Training: A Whole-System Approach and founder of the Parisi Speed School.

Your fascia is a whole-body network, much like your muscular and cardiovascular systems. You train those systems in the gym with weights and cardio. And you should train your fascial system, too, with specific moves. If you stimulate your fascia, you can help prevent many injuries and supercharge your muscles with extra power (and yes, you also improve the way your hip flexors feel and function). “Training the fascial system is the new science of speed, power, and injury resilience,” says Parisi, who has trained athletes for 30 years.

Fascia doesn’t show up on X-rays and MRIs, the traditional ways to study soft tissues, but recent advancements in ultrasound imaging technology have enabled researchers to study fascia and how it can contribute to enhanced athletic performance and human movement. They’ve learned that the fascial system is a single, interconnected web, primarily made of collagen and fluid, that surrounds everything in your body—muscles, bones, blood vessels, and so on.

This web has multiple functions. Your fascia can tighten to lend you stability in awkward positions. (Imagine contorting to reach into the backseat of your car.) Or like a spring, it can store energy when you crouch for a jump, then help deliver extra thrust when you launch off the floor. “It’s why athletes wear compression sleeves or tights, to get that feeling of warmth, springiness, and recoil, of free energy and stability around muscles and joints,” Parisi says. “Training your fascial network creates that feeling itself.”

Skip training that stimulates the fascia (or worse, barely move for hours on end) and it revolts. It’s programmed to respond quickly: Right now microscopic fibroblast cells are crawling through your body like spiders, secreting webs of collagen that form your fascial network. If you don’t move frequently, the web stiffens your muscles, which can eventually cause posture and movement imbalances. That can lead to your typical hip-flexor tightness and general body achiness. “Collagen is laid down based on the amount of stress you put on your body,” Parisi says. Stress your fascial network the right way and it becomes better at stabilizing your body and delivering more bounce.

Your go-to move, that foam roller, can relieve fascial stiffness, but it doesn’t develop fascial strength or springiness. The solution: Challenge your fascia by integrating multiplanar moves and other drills into your workouts. Make time for this and you’ll soon feel greater power, channeling your own suit of armor.