A hamstring strain is a common leg injury involving a strain or tear in one or more of the hamstring muscles. This can be graded and range from mild to very severe involving a complete tear of the hamstring muscle. You have four hamstring muscles: semimembranosus and semitendinosus (medially) and biceps femoris – short and long heads (laterally). The common reasons for a hamstring strain can be broken into 2 categories – primary and secondary:
- Poor timing-intermuscular coordination and eccentric strength in the hamstring muscles during the switch between late leg recovery and initial leg approach in the swing phase of sprinting (Woods et al. 2004).
- Lack of “stiffness” and eccentric strength in the hamstring muscles during the ground contact phase of running (Bosch and Klomp 2005). “Stiffness” refers to the ability of the hamstring muscle to absorb shock and rebound. Dropping a golf ball onto concrete is an example of stiffness, it immediately rebounds off the surface.
- Previous hamstring strain is a very good indicator of potential for future injury (Crosier 2004).
- Poor running mechanics. This consists primarily of overstriding or poor pelvic control, which puts the hamstrings in a vulnerable position at ground contact.
- Improper warm-up. Your warm-up must be active and dynamic to prepare the hamstring muscles for the forces involved. Passive stretching is only one segment of warm-up.
- Inappropriate training loads.Your hamstrings are primarily fast twitch Type II fibres that fatigue quickly. High-speed work should be done early in the workout, as close to warm-up as possible to avoid fatigue.
- Fatigue (neural and local muscle).
- Lower back pathology.Abnormalities of the lumbar spine or poor pelvic control that can cause nerve dysfunction and subsequent muscle weakness can predispose you to injury.
- Ankle sprain
- Knee ligament tear