It helps to have a working knowlege of the anatomy and pathophysiology (what happens on a cellular level after injury) when managing muscle injuries. At the microscopic level, muscles are arranged in small units or bundles. They are surrounded by protective layers of tissue and satellite cells. The satellite cells are a type of stem cell that stand by in case of injury. They start the healing response when it’s needed.
Muscle injury occurs when the muscle fibers are stretched too far, too fast. The strain or tear usually starts at the weakest part of the contractile unit. The weakest point of the muscle (where a strain is most likely to occur) is at the myotendinous junction. This is the transition zone between the muscle fibers and the tendon that attaches the muscle to the bone. The muscle is soft and pliable. The tendon is more like tough connective tissue and less resistant to sudden force.
Once an injury has occurred, the body responds quickly. First, it mobilizes inflammatory cells and sends them to the area of injury. That’s when we get pain, swelling, and a warmth or even hot feeling around the injured site. That’s the acute phase (first 24 to 48 hours).
Then, the satellite cells are activated to create new muscle fibers. They help knit the torn area back together over the next six to eight weeks. In the last phase of muscle healing, the body spends some time remodeling the tissue.
An early or acute injury is usually managed with the RICE principle (rest, ice, compression, elevation). The goal is to reduce swelling and pain while restoring motion. Over-the-counter drugs such as Tylenol for pain relief or ibuprofen (nonsteroidal anti-inflammatory drug or NSAID) may be presecribed during the early phases of healing and recovery (seven to 10 days).
Long-term use of NSAIDs is no longer advised. Animal studies have shown that muscle force and function can be inhibited with prolonged NSAID use. These drugs may reduce the number of satellite cells available for tissue regeneration.
Resting the injured muscle is a good idea at first but long-term immobilization should be avoided. At first, the pain prevents movement. And during the acute phase, keeping the muscle and joints still helps protect the injured area from further damage. Scar tissue formation is also less likely if the strained muscle is given a short rest from a repeated contract-relax sequence.
Gentle movement should be resumed within 48 hours. Usually, this coincides with a natural decrease in pain and swelling. The task now is to regain motion and eventually full strength. For athletes, a physical therapist or athletic trainer can be very helpful during this phase of rehab and recovery. Sports experts recommend waiting to resume sports activity until the injured side has at least 80 per cent of strength when compared to the uninjured side.