Hamstring strains frequently occur with eccentric contractions (eg. landing from a jump) or excessive range of motion (as in dashing for a bus if you don’t normally run).  Given the large size of this muscle group, a hamstring strain can be one of the most debilitating of sport injuries as well as one of the hardest to rehabilitate.  Strains are more likely to occur if: a) you neglect your warm-up; b) you have tight or weak hamstrings in comparison to the quadriceps (most often seen in runners and cyclists); c) you suffer from poor posture; d) you have leg length inequalities; or e) you suffer from ‘weekend warrior’ syndrome, turning out to exercise only once or twice a week.

For mild to moderate strains, there are three stages to healing and rehabilitation.  The first stage focuses on pain management and is the rest and protect phase lasting from 2 to 5 days.  Rest, ice, compression and elevation should occur immediately following the injury and be continued throughout this phase.  Starting exercise in this stage can lead to re-injury and disruption of the healing tissue.  The second stage can last up to six weeks, and involves both passive and dynamic loading of the healing tissue.  A common mistake during this phase is to focus solely on stretching the hamstrings, because the thought is that the injury is due to the muscle being ‘tight’.  However, as weakness is usually the primary issue, the focus should be on eccentric strengthening.  This is when the muscle is contracting while it is lengthening, and is the most effective way to build functional strength and endurance in muscle tissue.  The forward deep lunge is an excellent exercise to strengthen:  take a step forward and perform a deep knee bend with the front leg, so that the hamstrings are contracting as they are lengthening.  Another effective eccentric exercise is the kneeling hamstring curl:  kneel on a yoga mat and have someone restrain your ankles as you slowly lower your body while keeping your back straight.   Here you are adding a load to the hamstrings while they are lengthening to allow your torso to lean forward.  Adding some form of cross training to maintain aerobic capacity without straining the injured muscle is also appropriate.  The final stage lasts from 6 weeks until several months, and involves functional loading.  The goal of this phase is to fully strengthen the injured muscle so that it is at least equal in strength and length of the uninjured side.  A muscle may be strong enough to function at sub-maximal levels, but not strong enough to function at maximum levels.  Core strengthening can also help to prevent hamstring strains if there is an increase in the curvature of the lower back.  This causes an increase in the resting tension of the hamstrings, and therefore they are more inclined to fatigue early.