A<unk> can occur as a result of improper body mechanics with any activity (e.g., contact sports, lifting heavy objects) that can induce mechanical trauma or injury. Generally, the muscle or tendon overstretches and is placed under more physical stress than it can withstand.<unk>  commonly result in a partial or complete tear of a tendon or muscle, or they can be severe in the form of a complete tendon rupture.<unk>  most commonly occur in the foot, leg, or back. Acute<unk>  are more closely associated with recent mechanical trauma or injury. Chronic<unk>  typically result from repetitive movement of the muscles and tendons over a long period of time. 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 tissues; painful, limited motion; possibly some swelling or depression at the spot of the injury. * Third degree (most severe) – limited or no movement; severe acute pain, though sometimes painless<unk> ht after the initial injury To establish a uniform definition amongst healthcare providers, in 2012 a Consensus Statement on suggested new terminology and classification of muscle injuries was published. The classifications suggested were: : The major difference suggested was the use of "indirect" muscle injury verse "grade 1" to provide subclassifications when advanced images were negative. 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<unk>  are not restricted to athletes and can happen while doing everyday tasks, people who play sports are more at risk for developing a<unk>  It is common for an injury to develop when there is a sudden increase in duration, intensity, or frequency of an activity.
Strain 
Sprain
Serotype
Patellar tendon rupture
Course 
Isotype 
Killing Season
Dose 