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Reinforce the Lower Extremity

After the reset phase, the next step of rehabilitation is to reinforce the joint segment. Through a combination of corrective exercise, and conservative lifestyle modifications, the reinforce phase is focused on to maximizing the neuromuscular activation of the surrounding musculature to increase stability, which increases the amount of force the joint segment can generate (Cook, 2013). The goal is to increase the speed of muscle contraction and the motor output of the muscle group by challenging the sensorimotor system (Page, Frank, & Lardner, 2010). In this hypothetical case study, the reinforce is focused on lessening patellofemoral pain (PFP).

Monica is 35-year-old tennis player. She is normal weight and has no history of injury. Monica has been playing tennis since she was five, played in college, and appears to be in very good physical condition. Some of her training goals include increasing stamina, strength, and decreasing the pain in her knee. She plays tennis 4-5 times a week and has begun feeling pain in her left knee. The onset of PFP is slow and there is rarely an acute injury that causes the symptoms but rather an increase an exacerbation of symptoms with increased load (Norris, 2017). During Monica’s postural assessment, she demonstrated some signs of Lower Crossed Syndrome, such as a slight anterior pelvic tilt and a hyperlordotic lumbar region, indicating tight hip flexors and thoracolumbar extensors, and weak gluteals and abdominals (Page et al., 2010). She also has very developed quadriceps compared to her hamstring group, which may also be a source of her knee pain. During Monica’s gait assessment, she over pronates her left foot. This delays external rotation of the lower leg, which stops the knee from locking. This causes the femur to rotate instead, forcing the patella to track more laterally, which causes stress on the joint, leading to the genesis of PFP (Norris, 2017). Most of the Janda movement pattern tests show normal function except the hip abduction where her leg moved medially. This could indicate an overactive tensor fascia latae (TFL). The overactive TFL causes the IT band to act as a stabilizer, due to a weak gluteus medius. This leads to shortened fascial connections with the IT band and lateral patellar reticulum, which changes patellar tracking and increases stress on the knee cap (Page et al., 2010). During an overhead squat assessment, the form was normal, but Monica felt a slight pain in the front of the knee after five reps. Based on her assessment, Monica should first reset the musculature around the hip, by foam rolling and stretching the TFL and IT band. Her reinforce phase will consist of sensorimotor training, with both open and close chain exercises to optimize motor unit recruitment of the hip and knee musculature to help stabilize the knee and reduce Monica’s PFP.

Open chain exercises, where a limb is free to move, are a good starting point for the reinforce phase. While open chain exercises are more functional and require greater motor unit recruitment and coordination between muscle groups, they may worsen symptoms of PFP due to increased load on the joint (Norris, 2017). A good starting open chain exercise would be the quadruped circle. This exercise increases stabilization of the spine, and helps activate and strengthen the muscles in the hips, particularly the gluteus medius (Verstegen & Williams, 2004). To begin the exercise, Monica would begin on her hands and knees, with her core tight and shoulders positioned forward. Her hands should be positioned underneath her shoulders and her knees should be aligned with her hips. To perform the exercise, Monica should lift the left knee and tighten her glutes while lifting the leg to the outside of her hip. She should rotate it in a circle until it is back into the chest (Verstegen & Williams, 2004, pg. 67). She should feel the exercise in the hips during rotation. To advance the exercise, Monica can wrap a miniband around hip thighs, or a clinician can apply external pressure to thigh during the movement to give slight resistance.

Closed chain exercises, involve multijoint movement with a fixed lower limb. These exercises induce more muscle strength improvements and co-contraction greater muscle activation rates between agonistic and antagonistic muscle groups (T., As, A., & Vellaichamy, 2013). A good close chain exercise is the forward lunge. The exercise works the gluteals, quadriceps and hamstrings, and forces the client to engage the core (Liebenson, 2014). In the forward lunge exercise, Monica should begin by standing tall with her feet about shoulder width apart. She should take a large step forward with her left leg, and shift her weight anteriorly, so the heel contacts the ground first. She should then lower her body until her thigh forms a 90 angle. She should press downward with her heel and drive back up with her leg to the starting position (Liebenson, 2014 pg. 123). She should perform 10 reps and alternate legs with each repetition. To progress the exercise, Monica can flex hold her knee in the up position while coming to the staring position. This will force Monica to balance her self, and increase motor unit activation. Another progression is to wrap a resistance band around her waist while doing the forward lunge. This will force a weight shift and force Monica to increase her positional awareness, and challenge her base of support, which will increase motor unit utilization and coordination in the lower body and core (Page et al., 2010). Common mistakes to look out for in the forward lunge include, the client dropping the upper body over the led leg in the exercise, and lifting the lead heel. These mistakes can be remedied by keeping the abs activated, and by having the client take a slightly larger step and focusing on their heel.

The next exercise focuses on improving hamstring activation and improving sensorimotor control. Women are far more likely to experience knee injury during sports compared to male athletes, due to a combination of anatomic factors, hormonal factors, and neuromuscular factors (Hewett, 2000). Men activate their hamstrings during change of direction activities far more than women, which helps stabilize the knee joint. This increases the incidence of knee issues in women. In addition, weak hamstrings compared to quadriceps can cause knee pain or injury. A weaker hamstring group compared to a quadricep group, leads to decreased coactivation of the hamstring as an antagonist during gait and other actives, which can lead to increased stress on the knee (Rosene, Fogarty, & Mahaffy, 2001). For these reasons it would make sense for Monica to improve her hamstring strength and hamstring activation rate.

Challenging the base of support increases the speed of muscle contraction and the motor output of the muscle group (Page et al., 2010). By performing the inverted hamstring on an increasingly unstable surface increases hamstring strength and activation, more than performing the exercise on solid ground alone. To perform the inverted hamstring, Monica would begin balanced on her left foot, with her core tightened, and shoulders pulled back (Verstegen & Williams, 2004). To perform the movement, Monica will hinge at the waist, while extending her right leg back and squeezing the gluteals tightly. The shoulder and heel should form a straight line as she moves. She should return to the starting position and alternate legs ((Verstegen & Williams, 2004, pg. 44). The goal of this exercise is to activate the hamstring, improve flexibility and balance, and increase full body stabilization. To progress this exercise, Monica can perform the exercise on a foam surface, a rocker board, and then a wobble board. She should only progress if she can maintain quality movement throughout the exercise. The increasing instability of the surface will improve motor control, proprioception, and promote reflexive responses (Page et al., 2010). Once she has mastered each progression she should try the series with her eyes shut to further challenge her sensorimotor system.

The exercises in the reinforce phase of Monica’s rehabilitation should decrease her PFP. She should progress from an open chain exercise, like the quadruped circle, to an open chain exercise like the forward lunge. Once she displays enough motor control, the inverted hamstring and its variations are recommended. The motor unit recruitment of the hip and knee musculature will increase, leading to greater knee stability and less PFP.


Cook, G. (2013, September 18). The three Rs. Retrieved from

Hewett, T. E. (2000). Neuromuscular and hormonal factors associated with knee injuries in female athletes. Sports Medicine, 29(5), 313-327.

Liebenson, C. (2014). Functional training handbook. Philadelphia: Wolters Kluwer Health.

Norris, C. (2017). Patellofemoral pain syndrome: A practical treatment approach. Co-Kinetic Journal, (73), 14-18.

Page, P., Frank, C. C., & Lardner, R. (2010). Assessment and treatment of muscle imbalance: The Janda approach. Leeds: Human Kinetics.

Rosene, J. M., Fogarty, T. D., & Mahaffy, B. L. (2001). Isokinetic hamstrings:quadriceps ratios in intercollegiate athletes. ]’

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T., S. K., As, L. R., A., J., & Vellaichamy, V. W. (2013). Kinetic chain exercise for patellofemoral pain syndrome - a randomised control study. Indian Journal of Physiotherapy and Occupational Therapy - An International Journal, 7(3), 245-249.

Verstegen, M., & Williams, P. (2004). Core performance: The revolutionary workout program to transform your body and your life. Emmaus, PA: Rodale.

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