The Role of the Hamstrings in Distance Running and Why They Are Commonly Injured

Months and months of training go by and it is finally race day. You warm up and enthusiastically start your long-awaited marathon, get through 20 miles at your PR speed, and suddenly your leg begins tightening up and causes you to stop mid-run. Stretching and a bit of walking at the moment make zero difference and you carefully jog the last 6.2 miles to the finish line in disappointment. So many months were put into building up mileage to get to that 20-mile long run and you had so much confidence the rest of the marathon miles would be smooth. The legs just couldn’t handle the extra work on race day and the hamstrings ended up taking a toll for that last portion.

Many marathon training plans cap the long run at 20 miles, and some are just 16 miles! As long as all training components are completed properly and the body remains healthy throughout the cycle, the extra miles should be doable. But in many cases, the weak areas of the body will show their deficits once there comes a task that the body is not used to. Hamstring injuries and pain are one of the most common complaints among distance runners. This group of muscles plays a significant role in the running cycle, yet many athletes do not prioritize hamstring strength during training.

The Role of the Hamstrings

The hamstrings are in charge of bending the knee and extending the thigh behind the body. These motions are evident in the running cycle during the stance phase, which is when one foot is planted on the ground and the body begins to propel itself forward, and push-off, when the leg must remain behind the body until it needs to swing back to the front. Most runners will emphasize the importance of the quadriceps and calf muscles for these phases of running due to their need to concentrically contract to get through the motions. The quads are also the main muscles used in the entire stance phase, since they are in charge of extending the knee. Therefore from initial contact to midstance to propulsion, the quads are constantly contracting to control the amount of knee extension through the push-off.

Many runners become “quad-dominant”, meaning they place a large emphasis on high quad activation compared to other muscle groups during the running cycle. During this time the hamstrings become quite quieted and remain weaker. The hamstrings become easily ignored for this reason. Besides the direct knee flexor and hip extensor role, they play a very important role in the knee extension moments of the cycle. They are the muscles that control the rate of knee extension during the swing phase, as well as limit hyperextension during the stance phase. The only way these two functions are possible is if there is sufficient hamstring strength to begin with.

Quad vs. Hamstrings Strength

Research shows that most recreational runners have quad muscles 30 to 40% stronger than the hamstring muscles. This creates a big disadvantage to proper running mechanics and makes it difficult to increase speed. The general job of the hamstrings will automatically help extend the hip during push-off and keep the knee bent during the swing phase, but the other important work gets left solely to the quads. When the ratio of quad to hamstring strength is further away from 1:1 there is a much larger risk of injury. The quads may become significantly overused and end up not firing properly or enough, but the hamstrings are usually the muscle to take the beating during distance running.

Hamstring Injuries

Tendonitis or tendinopathy is the most common diagnosis in the hamstring muscle group. Tendonitis is basically inflammation of a tendon, which is the part of the muscle that inserts into a bone. This condition can occur in either the insertion point at the back of the knee joint or up in the hip area where the muscle inserts into the “sitting bone” in the rear, which is termed a high hamstring tendinopathy. The latter is more common in distance runners and usually occurs when increasing speed or intensity too quickly or beginning a hard workout without warming up. Other factors that increase the risk of developing HHT are weakness in the gluteal and core muscles, poor flexibility of the hamstrings, or uneven pelvic rotation. For runners, a common cause is muscle tightness and a poor ratio of quad to hamstring strength, as mentioned above.

If left untreated, this inflammatory condition may lead to a tear, which will most definitely put a long halt on any running. Usually tendonitis becomes severely painful in most cases that running is almost impossible to do. The most common symptoms of tendonitis are a deep, achy pain in the center of the buttocks once running is initiated, then a lessening of the pain after a few minutes, but a return of the nagging pain as running continues. This deep ache is usually felt once running is stopped for several hours. It is critical to treat hamstring tendinopathy as soon as it begins in order to avoid increased strain and possible tearing.

Treatment & Prevention

The most important part of hamstring injury recovery is a break from aggravating activities, which means running and other higher intensity exercise should be avoided. The main focus at this time should be getting rid of the inflammation through mechanisms such as icing, light massage and foam rolling, and elevation of the leg.

If the treatment is started right away, this phase is short. To prevent the tendonitis from returning, it is crucial to begin incorporating flexibility exercises for the hamstrings and other tight muscles in the hips, as well as hamstring and core strengthening. The goal should be to have as equal strength as possible between the quadriceps and hamstrings.

There are several components to a proper training program and it is important to make sure to incorporate each in order to avoid injury. Lacking the proper balance of muscle strength is a main cause of a variety of injuries in runners. Running requires a certain sequence of motions and the muscles must all work together to create efficient mechanics. The main difference in leg strength between highly-trained runners and recreational runners is the quad to hamstrings ratio. Keeping as close to a 1:1 ratio is ideal to ensure a higher running economy and less risk of injury.