The following is an excerpt from an article that Dean Benton, Performance Director, Brisbane Broncos Rugby League Club, Australia and I co authored for the Australian publication Sport Coach
- Poor timing-intermuscular coordination and eccentric strength in the short head of the biceps femoris muscle 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 short and long head of the biceps femoris muscle during the ground contact phase of running (Bosch & Klomp, 2005).
- Previous strain – Prior hamstring injury is a very good indicator of potential for future injury. (Crosier, 2004)
- Poor running mechanics – This consists primarily of overstriding which puts the hamstrings in a vulnerable position at ground contact. Also excessive sway or lateral deviations that force the synergistic stabilizing muscles to overwork subsequently shifting more stress to the hamstrings. The hamstrings do not work alone, they need help. Poor technique when running curves and angles will put more stress on the hamstrings because of the work they have to do in the transverse plane.
- Improper warm-up or lack of warm-up – There is often confusion between stretching and warm-up. Stretching is not warm-up, the warm-up must be active and dynamic to prepare the muscles for the forces involved. Stretching is only one segment of warm-up.
- Inappropriate training loads – High speed work placed inappropriately in the workout will predispose the athlete to hamstring pulls. The hamstrings are primarily fast twitch Type II fibers that fatigue quickly. This demands that high speed work be done early in workout, as close to warm-up as possible to avoid fatigue. Higher intensity speed endurance work must be gradually built into the program to allow for adaptation. This type of work must be built on a sound foundation of running mechanics.
- Fatigue (neural and local muscle) – Because the hamstrings are primarily fast twitch Type II fiber they fatigue quickly. All activities that occur in the course of a game must be taken into consideration e.g. in AFL fatigue from running then sprinting/kicking.
- Lower back pathology – Abnormalities of the lumbar spine that potentially could cause nerve dysfunction, which in turn lead to muscle weakness.
- Playing surfaces – A wet slippery surface will put more strain on the hamstring due to slipping.