Strain (injury)

A strain is a type of acute soft tissue injury that affects a muscle, specifically involving the tearing of some muscle fibers. (The comparable injury to a ligament is called a sprain.) Strains typically happen during an eccentric contraction, when a muscle is actively lengthening. While the body can heal strains on its own, various treatments can help manage the symptoms. **Signs and symptoms** Pain from a strain interferes with daily activities and makes it hard to generate strength, though actual muscle strength remains normal unless the muscle is completely ruptured. Physical signs include tenderness and pain when the muscle is stretched. Bruising and swelling are rare because muscles are located deep in the body. Strains range from mild overstretching to severe tears, depending on the extent of the damage. **Cause** Strains can result from improper body mechanics during any activity—such as contact sports or lifting heavy objects—that causes mechanical trauma. In general, the muscle or tendon is overstretched and placed under more physical stress than it can handle. This often leads to a partial or complete tear of the muscle or tendon, and in severe cases, a complete tendon rupture. Strains most commonly occur in the foot, leg, or back. Acute strains are linked to recent mechanical trauma, while chronic strains typically come from repetitive movement over a long period. **Degrees of Injury** (as classified by the American College of Sports Medicine) - First degree (mildest): Little tissue tearing; mild tenderness; pain with full range of motion. - Second degree: Torn muscle or tendon tissue; painful, limited motion; possible swelling or a depression at the injury site. - Third degree (most severe): Limited or no movement; severe acute pain (though sometimes painless right after the injury). To create a uniform definition among healthcare providers, a 2012 Consensus Statement proposed new terminology and classification for muscle injuries. The major change was using "indirect" muscle injury instead of "grade 1" when advanced imaging is negative. The suggested classifications are:

**Indirect Muscle Injury** - FUNCTIONAL (Negative MSK US & MRI) - Type 1: Overexertion-related Muscle Disorder - Type 1a: Fatigue induced - Type 1b: DOMS - Type 2: Neuromuscular muscle disorder - Type 2a: Spine-Related - Type 2b: Muscle-Related - STRUCTURAL MUSCLE INJURY (Positive MSK US & MRI) - Type 3: Partial Muscle Tear - Type 4: (Sub) total tear

**Direct Muscle Injury** - Bump or Cut: Contact-related

**Risk factors** Although strains can happen during everyday tasks, people who play sports—especially sprinting or team sports—are at higher risk. Injuries often occur when there is a sudden increase in activity duration, intensity, or frequency. **Treatment** First-line treatment for a muscular strain in the acute phase follows the five steps known as P.R.I.C.E.: - Protection: Apply soft padding to minimize impact with objects. - Rest: Necessary to speed healing and reduce the chance of re-injury. - Ice: Apply ice to cause vasoconstriction, reducing blood flow to the injury. Never ice for more than 20 minutes at a time. - Compression: Wrap the strained area with a soft bandage to reduce further diapedesis and promote lymphatic drainage. - Elevation: Keep the strained area as close to heart level as possible to promote venous blood return. Immediate treatment often combines NSAIDs with cold compression therapy. Cold compression reduces swelling and pain by limiting leukocyte extravasation into the injured area. NSAIDs like ibuprofen or paracetamol reduce inflammation by inhibiting Cox-1 and Cox-2 enzymes, which convert arachidonic acid into prostaglandin. However, NSAIDs (including aspirin and ibuprofen) affect platelet function—acting as blood thinners—and should not be taken while tissue is still bleeding, as they can increase blood flow, inhibit clotting, and worsen bleeding and swelling. Once bleeding has stopped, NSAIDs can help reduce inflammation and pain. A newer treatment for acute strains is platelet-rich plasma (PRP) injections, which have been shown to speed recovery from non-surgical muscle injuries. It is recommended to consult a medical provider if the injury involves severe pain, the limb cannot be used, or there is noticeable tenderness over an isolated spot. These signs may indicate a broken bone, a sprain, or a complete muscle tear.