The Scientist: Brian Hoke, D.P.T., a physical therapist and medical educator at Atlantic Physical Therapy in Virginia Beach, VirginiaThe Answer: If you’ve been sitting at the computer for too long and have that familiar tight pain in your back or shoulders, you may be suffering from muscle knots.While not a literal knot, a muscle knot—also called a myofascial trigger point—is essentially a small part of a muscle that is stuck in a contraction. The knots occur at points where your muscles and nerves interact, called neuromuscular junctions. While the precise mechanisms aren’t entirely clear, the basic idea is that a small portion of the muscle spasms, causing pain. The pain triggers more spasms, which lead to more pain, locking the muscle in a pain-spasm cycle.The initial spasms may be due to stress, injury or poor posture. For example, hunching over a computer during a tense deadline can cause the muscles in the shoulders, neck or back to shorten, and sitting this way continuously day after day can exacerbate knotting. Runners also often get knots near their heel or inner calves.To prevent knots, try taking breaks from knot-inducing activities to stretch and lengthen vulnerable muscles. To treat existing knots, the goal is to break the pain-spasm cycle—knock one element out, and the other will also likely abate.You may be able to do this on your own. To get rid of the muscle spasm, try gently stretching, which lengthens the muscle in question, or applying heat, which encourages blood flow and may help the muscle relax. Pressure can release a knot, too. Try massaging the muscle with your hand for spots you can reach. For inaccessible places on your back, put a tennis ball in a sock or a pillowcase, toss it over your shoulder so that the ball rests on the trigger point, and then lean against the wall and shift your weight back and forth so that the ball massages your muscle (think bear scratching its back on a tree). This also works on the floor for lower back and hip pain.For severe trigger points that resist these methods, try icing the area to numb it, which may break the pain portion of the pain-spasm cycle. If none of these at-home tactics work, soft tissue experts might help. Massage therapists, physical therapists and body workers have many tricks for unraveling the knottiest trigger points.MORE:Tips to Prevent Back PainHow to Sit at Your Desk Without PainWhen Is Muscle Soreness Good?