During this early protective phase, the hamstring muscle group should be kept in a shortened and relaxed position to avoid excessive strain or tension on the repair site. The patient should avoid sitting directly on the ischial tuberosity except when using a raised toilet seat. The patient is permitted to be partial or toe-touch weight bearing with bilateral axial crutches at this time [44, 45]. The only exercises recommended during this period are isometric gluteal and quadriceps sets, ankle pumps, and assisted heel slides allowing no more than 30–45° of knee flexion. These exercises should be included in the patients early home exercise program [45].

After the first postoperative week it is recommended that the individual attend formal physical therapy at a frequency of 1–2 times per week. If immobilized postoperatively, the patient would be placed in a custom knee brace allowing full knee flexion but limiting the last 30° of extension [44]. Once the patient can demonstrate 30° of hip flexion during a straight leg raise, the patient is permitted to ambulate weight bearing as tolerated with short step lengths while continuing to use bilateral axial crutches. The patient is instructed to add single-leg balance and progress to mini knee bends while in single-leg stance when able. Other exercises deemed safe during this period include isometric hamstring muscle contractions and passive knee flexion and extension range of motion while in prone position [45].

If the patient is able to complete exercises included in week 2 without increasing pain or reactive effusion, additional exercises may be added. The clinician should monitor the patient closely during and after exercise and should exercise caution with progression or additions of higher level exercises. Exercises that can be added in the third postoperative week are standing hamstring curls, stationary marching on thick pad, and heel raises [45].

Typically, between the fourth and sixth postoperative week the patient may begin to utilize an upright stationary bike to improve range of motion and flexibility [44, 45]. The seat height should be set in a high position allowing the patient to reach 70° of hip flexion with 90° of knee flexion. At this time exercises from the first 3 weeks may be discontinued and more specific lower extremity strengthening exercises may commence. The patient should be monitored to ensure that exercises are performed with correct technique and performed slowly during this period. Isometric hamstring curls while seated and bridges can be added at this time [45].

If postoperative bracing was used, the patient would be permitted to be full weight bearing with full knee range of motion after 6 weeks [44]. At this point in the recovery phase, the emphasis should be on normalizing the patient’s gait pattern. Additional exercises including prone isometric hamstring contractions and higher level single-leg balance exercises are also included at this time. The patient can bias the medial or lateral hamstring muscles during prone hamstring isometrics by internally or externally rotating the leg, respectively [45].

Lower extremity strengthening exercises can be progressed during this period. Technique should be monitored and progression of intensity or resistance should be based on patient’s tolerance and response to exercise. Suggested lower extremity strengthening exercises include mini squats, step downs, leg press, hip abductor strengthening while standing with use of tubing or machine, and higher level proprioceptive and balance training [46]. Hamstring curls in prone position on a machine can be initiated. The patient should start in prone position then progress to seated hamstring curls with hip positioned in 90° of flexion [46]. Other safe hamstring exercises which maintain the hamstring in midrange positions can be initiated as tolerated and include heel slides, double-leg bridges, and standing leg extensions [47] (Fig. 12.2).

Eccentric strength training is recommended to begin at this time ensuring at least 2 days of rest a week. In order to progress the patient safely, eccentric exercises should begin in midranges and be performed bilaterally. Progressions of eccentric exercises may include single-leg forward leans, single-leg bridge lowering, and assisted Nordic curls [47]. The treating clinician should perform manual strength assessment with the patient in a prone position with the knee and hip extended. This assessment should be performed on a weekly basis to determine progress. As the rehab program progresses, other testing positions should be included to assess for pain and strength deficits. A side-to-side comparison of strength and range of motion is recommended in order to identify impairments and asymmetry. Askling et al. recommend that patients should perform 2–4 hamstring exercises during each physical therapy or home training session focusing more on quality and control of the movement rather than quantity. Exercise should be monitored and patients should be educated regarding correct technique and form to limit compensatory movements. Patients will often demonstrate gluteus maximus, adductor magnus, and gastrocnemius activation to assist the weakened or dysfunctional hamstrings with hip or knee motion [45].

Between weeks 12 and 16 forward and backward fast walking and cautious light jogging with short strides may be initiated [44]. It is recommended that stationary jogging with high knee lifts be included gradually increasing intensity and duration over time. Bridges should be progressed to single-leg bridges at this time (Fig. 12.3). This exercise can be further progressed by moving the foot farther away from the hip leading to increased knee extension. Pendulums or forward/backward leg swings can be included to improve the flexibility of the hamstrings.

As the patient continues to progress, specific hamstring strengthening exercises should be combined with more complex movements such as lunges, squats, and different low-level plyometrics (Fig. 12.4). Additionally, hamstring strengthening can progress toward higher velocity strengthening in lengthened positions; an example would be weighted single-leg dead lifts [47] (Fig. 12.5).

As the patient’s strength, flexibility, and tolerance to higher volumes and intensity of exercise increase, the clinician should begin to include more sport-specific movements or activities. During this transition from rehabilitation toward sport participation, the clinician should continue to assess the individual’s strength, range of motion, and confidence to ensure safe return to sport. Lefevre et al. recommended that regular sport activities could be started between postoperative weeks 16 and 32 [44]. In addition to general time guidelines, Askling et al. state that patients should demonstrate the ability to complete jumping, running, and cutting activities without pain, stiffness, or feelings of decreased confidence or insecurity before returning to pre-injury sport activities [45]. See “Return-to-Sport Criteria and Testing” section for criteria for RTS progression.