Purpose:Although closed (CKCE) and open (OKCE) kinetic chain exercises are used in athletic training and clinical environments, few studies have compared knee joint biomechanics while these exercises are performed dynamically. The purpose of this study was to quantify knee forces and muscle

Biomechanics of the knee during closed kinetic chain and open kinetic chain . exercises

ESCAMILLA, R. F. Knee biomechanics of the dynamic squat exercise. Med. Sci. Sports Exerc., Vol. 33, No. 1, 2001, pp. 127‐141. Purpose: Because a strong and stable knee is paramount to an athlete’s or patient’s success, an understanding of knee biomechanics while performing the squat is helpful to therapists, trainers, sports medicine physicians, researchers, coaches, and athletes who are interested in closed kinetic chain exercises, knee rehabilitation, and training for sport. The purpose of this review was to examine knee biomechanics during the dynamic squat exercise. Methods: Tibiofemoral shear and compressive forces, patellofemoral compressive force, knee muscle activity, and knee stability were reviewed and discussed relative to athletic performance, injury potential, and rehabilitation. Results: Low to moderate posterior shear forces, restrained primarily by the posterior cruciate ligament (PCL), were generated throughout the squat for all knee flexion angles. Low anterior shear forces, restrained primarily by the anterior cruciate ligament (ACL), were generated between 0 and 60° knee flexion. Patellofemoral compressive forces and tibiofemoral compressive and shear forces progressively increased as the knees flexed and decreased as the knees extended, reaching peak values near maximum knee flexion. Hence, training the squat in the functional range between 0 and 50° knee flexion may be appropriate for many knee rehabilitation patients, because knee forces were minimum in the functional range. Quadriceps, hamstrings, and gastrocnemius activity generally increased as knee flexion increased, which supports athletes with healthy knees performing the parallel squat (thighs parallel to ground at maximum knee flexion) between 0 and 100° knee flexion. Furthermore, it was demonstrated that the parallel squat was not injurious to the healthy knee. Conclusions: The squat was shown to be an effective exercise to employ during cruciate ligament or patellofemoral rehabilitation. For athletes with healthy knees, performing the parallel squat is recommended over the deep squat, because injury potential to the menisci and cruciate and collateral ligaments may increase with the deep squat. The squat does not compromise knee stability, and can enhance stability if performed correctly. Finally, the squat can be effective in developing hip, knee, and ankle musculature, because moderate to high quadriceps, hamstrings, and gastrocnemius activity were produced during the squat.

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Knee biomechanics of the dynamic squat exercise.

The effects of weightbearing (closed kinetic chain) and nonweightbearing (open kinetic chain) exercises on the biomechanical behavior of an injured anterior cruciate ligament or a healing anterior cruciate ligament graft are unknown. To understand the effects of these exercises on the healing graft, we measured the strain behavior of the normal anterior cruciate ligament in human subjects while they performed squatting, a closed kinetic chain exercise, and active flexion-extension of the leg, an open kinetic chain exercise. The maximum anterior cruciate ligament strain values obtained during squatting did not differ from those obtained during active flexion-extension. Also, anterior cruciate ligament strain values obtained during squatting were unaffected by the application of elastic resistance intended to increase muscle activity. These findings indicate that squatting, which produces a substantial compressive joint force, does not necessarily protect the anterior cruciate ligament more than active flexion-extension of the leg, which is characterized primarily by contraction of the dominant quadriceps muscle. These findings also demonstrate that increasing resistance during the squat exercise does not produce a significant increase in anterior cruciate ligament strain values, unlike increased resistance during active flexion-extension exercise.

The Strain Behavior of the Anterior Cruciate Ligament During Squatting and Active Flexion-Extension A Comparison of an Open and a Closed Kinetic Chain Exercise

Background and Purpose. Central activation failure and muscular atrophy are common after knee joint injury. Thus, exercises that aim to stimulate muscular hypertrophy and increase neural drive to the muscle fibers should be used during rehabilitation. This study examined the level of knee joint neuromuscular activation during 4 conventional therapeutic exercises (quadriceps femoris muscle setting, manual lateralization of the patella, rhythmic stabilization, and the pelvic bridging exercise) and 4 heavy resistance exercises (free-weight squat with a barbell, horizontal seated leg press, isolated knee extension with a cam mechanism, and isolated hamstring muscle curl) in young, untrained men who were healthy.

Subjects. Thirteen male subjects (mean age=25.3 years, SD=3.0) with no previous history of knee injury participated in the study.

Methods. Neuromuscular activation during the exercises was defined as the root-mean-square (RMS) electromyographic (EMG) signal normalized to the peak RMS EMG signal of a maximal isometric muscle contraction.

Results. Low levels of neuromuscular activation were found during all conventional exercises (<35%). A limitation may be that only a few of many different conventional exercises were investigated. The highest level of neuromuscular activation (67%–79%) was observed during the open kinetic chain resistance exercises (isolated knee extension and hamstring muscle curl). None of the conventional exercises or heavy resistance exercises were found to preferentially activate the vastus medialis muscle over the vastus lateralis muscle.

Discussion and Conclusion. The results indicate that heavy resistance exercises should be included in rehabilitation programs to induce sufficient levels of neuromuscular activation to stimulate muscle growth and strength.

Neuromuscular activation in conventional therapeutic exercises and heavy resistance exercises: implications for rehabilitation.

We conducted a prospective, randomized study of open and closed kinetic chain exercises during accelerated rehabilitation after anterior cruciate ligament recon struction to determine if closed kinetic chain exercises are safe and if they offer any advantages over conven tional rehabilitation. The closed kinetic chain group used a length of elastic tubing, the Sport Cord, to per form weightbearing exercises and the open kinetic chain group used conventional physical therapy equip ment. Results are reported with a minimum 1-year fol lowup (mean, 19 months). Pre- and postoperative evaluation included the Lysholm knee function scoring scale, Tegner activity rating scale and KT-1000 ar thrometer measurements. Overall, stability was re stored in over 90% of the knees. Preoperative patel lofemoral pain was reduced significantly; 95% of the patients had a full range of motion. The closed kinetic chain group had lower mean KT-1 000 arthrometer side- to-side differences, less patellofemoral pain, was gen erally mo...

Open Versus Closed Chain Kinetic Exercises After Anterior Cruciate Ligament Reconstruction: A Prospective Randomized Study

The purpose of this study was to quantify the amount of anterior tibial displacement occurring in anterior cru ciate ligament-deficient knees during two types of re habilitation exercises: 1) resisted knee extension, an open kinetic chain exercise; and 2) the parallel squat, a closed kinetic chain exercise. An electrogoniometer system was applied to the anterior cruciate ligament- deficient knee of 11 volunteers and to the uninvolved normal knee in 9 of these volunteers. Anterior tibial displacement and the knee flexion angle were meas ured during each exercise using matched quadriceps loads and during the Lachman test. The anterior cru ciate ligament-deficient knee had significantly greater anterior tibial displacement during extension from 64° to 10° in the knee extension exercise as compared to the parallel squat exercise. In addition, the amount of displacement during the Lachman test was significantly less than in the knee extension exercise, but signifi cantly more than in the parallel squat exercis...

H. John Yack

Papers

Comparison of closed and open kinetic chain exercise in the anterior cruciate ligament-deficient knee