The hamstrings are the cluster of muscles (and tendons) at the rear of the thigh -- technically, the posterior thigh muscles. The principal muscles are the bicep femoris, semitendinosus, and semimembranosus. They attach, via tendons, from the pelvis to the lower leg bones. In early English, the thigh was the hamm.
The hamstrings are involved in just about any bipedal movement that you do, in addition to providing strength and stability in stationary movements like squatting, standing on the toes or even swiveling the waist. These are elemental muscles. Even so, the hamstrings are not worked hard in casual activity, but they are crucial in power and performance movements like running and sprinting.
How are Hamstrings Injured?
Hamstrings, mainly the biceps femoris, suffer injury when the muscle is extended to the point where a muscle strain or tear occurs. Rankings for hamstring injuries are from Grade 1, minor strain, to Grade 3, rupture of a muscle. Grade 3 injuries can be severe, painful and require much rehabilitation. They are common in power athletes.
When you 'pull' a hamstring, it can feel like being shot or speared in the leg, and often a 'pop' is heard. (Author's personal experience.) Within a few days, deep and extensive blue-black bruising can occur.
In running at least, just prior to the leading leg striking the ground (swing phase), the hamstrings pull that lower leg (tibia) up under control so that it does not overextend the knee joint, which would be inefficient and potentially injurious. It is at this point of muscle lengthening and then sudden contraction that the hamstring is most vulnerable to injury.
Other factors that have been considered in hamstring susceptibility to injury are as follows, but most are more likely to be contributory factors rather than primary causes of hamstring injury.
- Inadequate warmup
- Dominant quadriceps (front of thigh) strength
- Poor running mechanics
- Previous hamstring, knee or pubis injury
- Less than ideal lower back and core muscle strength and mobility
- Quadriceps inflexibility
- Hamstring muscle inflexibility
- Ankle inflexibility
- Age - older more susceptible
Exercises for Hamstring Strengthening
Here are four key exercises to strengthen the hamstrings.
Use a special bench to do this or manufacture one.
Grade 1 strains should repair themselves in a week or two, although you might want to take care not to work that leg hard until you're sure things are fixed. Grade 2 strains are best referred to a medical practitioner, preferably one with sports medicine experience. A physical therapist or experienced exercise physiologist or strength and conditioning coach may also advise on rehabilitation exercises. Grade 3 tears are serious business and you will require medical attention and physical therapy. Crutches may be required in the early weeks, and you may be out of action for six weeks, depending on damage and rehab response.
Stretching may be of some benefit for very tight hamstrings, but this may not be the primary cause of hamstring injuries. And after all, that 'spring' is where you get locomotive power from and you really don't want to dilute it excessively.
Ultimately, strengthen the hamstrings with exercise and training; ensure they get adequate rest, run and lift hard, and hope for the best!