Don't Get Hamstrung! The Anatomy, Recovery Stages, & Exercise Progressions

The hamstrings! This is a muscle or collection of three or four specific muscles (depending how one separates them out) composed of the semitendinosus, semimembranosus, and the bicep femoris. Of these identified muscles the bicep femoris has two heads, the long head and the short head. The semimembranosus and semitendinosus sit along the medial aspect of the posterior thigh while the bicep femoris sits along the lateral aspect of the posterior thigh. What makes the hamstrings an interesting structure is that it is both a one and two joint muscle. This means semitendinosus, semimembranosus, and the long head of the bicep femoris cross two joints while the short head of the bicep femoris crosses only one joint.  While the semitendinosus, semimembranosus and the long head of the bicep femoris all attach above the hip at the ischial tuberosity and below the knee on the tibia, the short head of the bicep femoris attaches along the shaft of the femur and like the other three structures attaches down below the knee. Therefore, the hamstrings are responsible for not only hip extension and knee flexion but also some medial and lateral rotation of tibia. Another interesting aspect of the hamstring is that it is dual innervated; it has two nerve supplies. While the tibial division of the sciatic nerve innervates the long head of the bicep femoris, semitendinosus, and semimembranosus, the fibularis division of the sciatic nerve innervate the short head of the bicep femoris.

The hamstrings are one of the most injured muscles in sports. There are many reasons for why a hamstring may be injured however one strong reason for a hamstring injury is due to having had a previous hamstring injury. The rate or risk in injuring the hamstring may be due to its dual innervation thus leading to mistiming of its contraction. Other findings that suggest reasons for increased rates of injury include the muscles pennation angle relative to its fascicle length, general strength of the muscle, abnormal trunk and pelvic posture with an anterior pelvic tilt increasing the risk, and impaired motor control(1). According to an article in Ortho J Sports Med: Epidemiology of Hamstring Tears in NCAA Sports and an article in Athletic Training and sports medical care: Hamstring Strain Incidence Between Genders and Sport in NCAA Athletics, hamstring tears are one of the most common muscular injures seen in athletes; most especially in those athletes who participate in sprinting, jumping or other explosive - based tasks.  Of interest and of need for further prevention-based programing is that incidence of hamstring tears remains higher among men’s sport than women’s sports. Also pointed out was the higher rate of strains when accounting for the amount of uninterrupted play time relative to the amount of rest time.

As mentioned, the hamstrings are not only at risk for injury in sport but they are also at risk for reinjury as well. When rehabilitating the hamstrings, a sound treatment program is going to be key to helping to prevent re-injury.  According to the Journal of Orthopedic and Sports Medicine Clinical Practice Guideline, clinicians should assess for hamstring length and strength, consider pelvic and trunk posture, and motor control. It is also recommended that eccentric loads be applied within the patient tolerance, a progressive return to running program, and a progressive agility and trunk stability program be included in the rehabilitation program. The guideline also highly suggests that the Nordic Curl be included into the comprehensive program as a means of prevention of a hamstring injury or a reoccurrence of a hamstring injury. Another protocol used for hamstring injuries is the Asperter Score. This is a criterion-based protocol with six stages; three rehabilitative stages and three sports-based stages. In summary,

· The first stage: promote healing of the injured tissue

· The second and third stages: regain full muscle function

· The fourth through sixth stages: reintegrate patient back into sports specific participation.

With that being said, there is a protocol for overall assessment that includes objective measurements such as gait, palpation, range of motion, and strength assessment. Upon completion of the objective measurements the exercise components can begin.

The exercise components include:

·       The double leg squats

·       The exercise bikes

·       The double leg supine bridge

·       Isometric heel digs

·       Single leg squats with progressions to that with loads

·       Manual resistance in multiple angles

·       Soft tissue mobilizations

·       Active range of motion

·       Lengthening exercises including extenders, divers and gliders

·       Single leg supine bridge

·       Stretching

·       Prone hamstring curl

·       Nordic hamstring curl

·       Running progressions

As a parting note, The Ask Mike Reinold Show just aired and episode on February 8th 2024 a new episode called, when is it Safe to Start Running After a Hamstring Strain? This was a nice short and to the point podcast that referenced the protocols described in the Aspertar Protocol.

Using the progressive overload concept, the following is a list, not all-inclusive, that can be utilized in the effort to help rehabilitate the patient with a hamstring injury or to help prevent one from occurring. Some may overlap with the Aspertar Scale. Enjoy!

a) Standard bridges and progressions

b) Elevated bridges and progressions

c) Hamstring curls

d) Hamstring walkouts

e) Double leg to single leg loading

f) Nordic Curl

Resources/References:

1)     Dutton Orthopedics: Examination, Evaluation, and Intervention., 5th Ed.

2)     Boltz A, Wait J, Cheatham S, O’Connell R, Chandran A, Hooper N. Poster 190: Epidemiology of Hamstring Tears in NCAA Sports: 2014/15-2018/19. Orthop J Sports Med. 2022 Jul 28;10(7 suppl5):2325967121S00751. doi: 10.1177/2325967121S00751. PMCID: PMC9344175.

3)     Cross, KM,MS, ATC, PT, Gurka, KK, PhD, Conaway, M, phD, Ingersoll, CD, PhD, ATC: Hamstring Strain Incidence between genders and sport in NCAA athletics. Athletic Training & Sports Health Care, 2010;2(3):124–130

4)     Journal of orthopedics and sports physical therapy; JOSPT Vol 52; No 3. March 2022.

5)     Aspetar Guidelines for HS rehabilitation: www.aspertar.com

6)     The Ask Mike Reinhold Show: When is it Safe to Start Running After a Hamstring Strain? – AMR#329. February 8th 2024.