About Hamstring Function, Injury, Rehabilitation

What They Are and How to Care for Them

Deadlifts
Deadlifts of Various Types. (c) Paul Rogers / Cooloola Fitness

The hamstrings (hammies) are a group of muscles at the rear of the upper leg. They include the biceps femoris, semitendinosus, and semimembranosus. The hamstrings flex the knee joint, adduct the leg (move closer to the body), and extend the thigh.

Hamstring injuries are the most frequent muscle injury in running sports, especially speed and power sports. Read a full analysis of hamstring injury causes and preventive strategies.

What Causes Hamstring Injury?

Relative uncertainty exists about the prevention, causes and best methods of rehabilitation of hamstring injuries. Firm conclusions are in a minority and theoretical approaches in the absence of strong experimental studies are the norm. Here is a sample of the possible causes of hamstring injuries discussed in sports medicine:

  • Less than ideal lower back and core muscle strength and mobility
  • Hamstring muscle inflexibility
  • Quadriceps inflexibility
  • Ankle inflexibility
  • Quadriceps versus hamstring strength imbalance
  • Less than ideal running mechanics
  • Age -- older equals more susceptible
  • Previous hamstring, knee or pubis injury
  • Inadequate warmup
  • Fatigue

Being older and having a previous hamstring injury seem to be consistent with injury but not much else. Even hamstring inflexibility or quadriceps/hamstring strength imbalance, factors consistently touted as causes of hamstring injury, do not seem to be consistent factors in injury.

  • How hamstrings tear. In running at least, it seems hamstrings are most susceptible to injury in the 'eccentric' transition phase of movement when the muscle is lengthening during stride and being 'pulled up' for ground contact.
  • Stretching hamstrings. There is no consistent evidence that a static stretching program prevents hamstring injury or even that 'tight' hamstrings predispose to injury. Static stretching may even make things worse in some circumstances. Dynamic stretching is a preferred warm up. Stretching may have a useful role in hamstring rehabilitation.
  • Quadriceps imbalance. A hamstring less than 60 percent as strong as the quadricep (thigh front) supposedly predisposes to hamstring injury. Some studies show this muscle imbalance to be associated with hamstring injuries and others do not. Despite uncertainty, getting those hammies up over that 60 percent threshold seems to make sense and it may prevent anterior cruciate ligament injury (ACL) of the knee.

Exercises

Some of the best exercises for strengthening the hamstrings are with weights in the gym. Eccentric exercises that simulate the 'catch' of the swing phase of running may be particularly useful. Always warm up before weight training. Hamstring warm ups could include leg swings forward and rear, the standing bicycle action exercise, and light weight leg curls.

Standing leg curls with catch

  1. Start with a light weight on the standing leg curl machine. Lift the leg with weight back in the concentric phase, pause, then as you start to lower the leg, let the weight free fall and catch it near the bottom of this eccentric phase.
  1. Your leg does not actually have to lose contact with the weight, only allow a sudden 'drop and catch'. This simulates to some extent the eccentric swing phase during running.
  2. Eccentric exercise is known to cause muscle soreness, so go easy to start with.

Nordic reverse curl, glute-ham curl

  1. Kneel on the floor with feet extended flat to the rear and the trunk upright at 90 degrees, preferably with some soft support under the knees. Support the feet under a low bench or get a partner to hold the feet down.
  2. Bend forward until your body is at an angle to the ground under eccentric hamstring control, then snap backward to the starting position with the help of the hands. Use the hands to stabilize this part if necessary so you don't fall on your face! Don't try too hard to straighten up under hamstring control because the eccentric strength on the down movement is the main target, not the concentric movement when you straighten up.
  3. See a demonstration of the Nordic reverse curl (called floor glute-ham raises in this article). A glute-ham raise bench is also available but few gyms provide this.

Deadlifts - Romanian, straight-legged, stiff-legged

The deadlift is the exercise where you lift the barbell from the floor to a standing position. If you perform this with the legs somewhat straighter, rather than squatting right down with knees bent for the lift and replace, you will feel the hamstrings tense up. However, keeping the legs straight while bending the back in a curve is danger territory for back injury for inexperienced lifters, even if the weight is light. Here is what I do. This is usually called a Romanian deadlift or RDL.

  1. Choose a suitable bar and plate or barbell weight that you can lift comfortably to the upright deadlift position at the thighs -- but not too light. Keeping the legs straight or only slightly bent, lower the bar until it reaches a position where you can feel the hamstrings at the back of the legs start to work.
  2. Stop somewhere around the shins -- don't go to the floor -- then return to the upright position. Don't overdo this to the point of pain or discomfort in the lower back and try to keep that back straight rather than curved over if possible. Bend the knees slightly if necessary.
  3. Be aware that the standard deadlift from the floor is also an excellent all-around strengthening exercise for the posterior chain of muscles of the lower back, butt, and hamstrings, and also the abdominals, all of which may have a role in maintaining hamstring viability.

Barbell good mornings

This is another excellent all-round exercise for the posterior chain including the hamstrings.

  1. Take a barbell and place it behind the neck on the shoulders in similar position as for the back squat.
  2. While keeping the legs stiff, bend forward at the hips with the barbell still resting on the shoulders and the back straight but not bent over at the upper spine. Keep the head steady.
  3. You will feel the dynamic stretch in the hamstrings. Don't overdo the weight to begin with. See a demonstration of a Barbell Good Morning.

Note. You could do several of these hamstring exercises on the same day and perhaps you should after a progressive period of conditioning. At the start, you need to go easy to prevent excessive soreness, particularly with eccentric training.

Three sessions per week is probably optimal. Do only two sessions if soreness is a problem. Modify the number of sets if necessary. A gradual increase in volume is the key to success.

Rehabilitation

Rehabilitation from hamstring injury, particularly grades 2 and 3, the more severe injuries, requires the supervision of a sports doctor, physical therapist or trainer with expertise in sports injury rehabilitation. The exercises listed above are useful in strengthening the hamstrings for injury prevention purposes and may be used in rehabilitation, but it's best to progress according to a plan under supervision.

Sources

Mjolsnes R, Arnason A, Osthagen T, Raastad T, Bahr R. A 10-week randomized trial comparing eccentric vs. concentric hamstring strength training in well-trained soccer players.Scand J Med Sci Sports. 2004 Oct;14(5):311-7.

Gabbe BJ, Bennell KL, Finch CF, Wajswelner H, Orchard JW. Predictors of hamstring injury at the elite level of Australian footballScand J Med Sci Sports. 2006 Feb;16(1):7-13.

Cochrane Database Syst Rev. 2012 Dec 12;12:CD004575. Rehabilitation for hamstring injuries. Mason DL(1), Dickens VA, Vail A.

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