A hamstring strain is an excessive stretch or tearing of muscle fibers and related tissues. Hamstring strains are classified as either 1st, 2nd, or 3rd degree depending on the severity. A hamstring strain can occur during an isolated athletic activity (acute) or result from persistent repetitive stress (chronic). Often an acute strain occurs as a result of a chronic condition which has rendered the muscle weak and vulnerable .
Hamstring strains often occur while sprinting. They also can occur during jumping and other activities where quick starts and stops are required. High risk sports for hamstring strains are: soccer, football, baseball, basketball, and many track and field events. Runners are especially susceptible to chronic hamstring strains due to the repetitive nature of the sport.
As a general rule of thumb, any activity that elicits pain at or near the injured site may be causing further injury and will only hamper your recovery effort. Don't be amongst the foolish many who attempt to play through a painful hamstring strain only to turn what might have been a short recovery into a painfully chronic one!
A gradual conditioning program, specific to your activity, will prepare the hamstrings for the high demands placed upon them during athletics. A proper warm-up and stretching session must be incorporated into your conditioning program.