QUADRICEPS FEMORIS MUSCLE ACTIVITY THROUGH THE KNEE EXTENSION RANGE OF MOTION

The distal part of the vastus medialis (VM) (VM obliquus: VMO) muscle acts as the medial stabilizer of the patella. However, it has been known to facilitate VMO contraction during training of the quadriceps femoris muscle in knee joint rehabilitation. This study aimed to examine the contribution degree of VMO as a knee joint extension torque generator. Sixteen healthy male volunteers participated in this study. Electrical muscle stimulation (EMS) was performed on VMO at 60° knee angle for 20 min to induce muscle fatigue. Knee extension twitch torques (TT) at 90° and 30° knee angle evoked by femoral nerve stimulation were measured before and after EMS. Although each TT at 90° and 30° knee angle significantly decreased after EMS, the decreased TT rate in both joint angles showed no significant difference. Our results show that VMO might contribute to the generation of the knee joint torque at the same level in the range from flexion to extension. Therefore, it was suggested that the facilitating the neural drive for VMO is important during the quadriceps femoris muscle strengthening exercise.

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Voluntary Activation and Decreased Force Production of the Quadriceps Femoris Muscle After Total Knee Arthroplasty

Physical Therapy ◽

10.1093/ptj/83.4.359 ◽

2003 ◽

Vol 83 (4) ◽

pp. 359-365 ◽

Cited By ~ 114

Author(s):

Ryan L Mizner ◽

Jennifer E Stevens ◽

Lynn Snyder-Mackler

Keyword(s):

Total Knee Arthroplasty ◽

Knee Arthroplasty ◽

Force Production ◽

Knee Extension ◽

Quadriceps Femoris ◽

Voluntary Activation ◽

Quadriceps Femoris Muscle ◽

Extension Force ◽

Total Knee ◽

Femoris Muscle

Abstract Background and Purpose. Quadriceps femoris muscle weakness as manifested by a decrease in force-generating capability is a persistent problem after total knee arthroplasty (TKA). The authors hypothesized that (1) patients with a TKA would have decreased quadriceps femoris muscle performance (weakness) and impaired volitional activation when compared with a group of older adults without knee pathology, (2) pain and age would account for a large portion of the variability in volitional activation after surgery, and (3) volitional activation in the TKA group would account for a large portion of the variability in force production. Subjects. Comparison subjects were 52 volunteers (mean age=72.2 years, SD=5.34, range=64–85). The TKA group comprised 52 patients (mean age=64.9 years, SD=7.72, range=49–78) with a diagnosis of osteoarthritis who had undergone a tricompartmental, cemented TKA. Methods. Knee extension force was measured using a burst superimposition technique, where a supramaximal burst of electrical stimulation was superimposed on a maximal voluntary isometric contraction (MVIC). The amount of failure of volitional activation is determined by the amount of electrical augmentation of force beyond a person's MVIC at the instant of the application of the electrical burst. Results. The average normalized knee extension force of the TKA group was 64% lower than that of the comparison group. The average volitional activation deficit in the TKA group (26%) was 4 times as great as the comparison group's deficit (6%). Age did not correlate with quadriceps femoris muscle activation, and knee pain explained only a small portion of the variance in knee extension force (r2=.17). Volitional activation was highly correlated with knee extension force production (r2=.65). Discussion and Conclusion. Considerable quadriceps femoris muscle inhibition after surgery has several implications for recovery. Rehabilitation programs that focus on volitional exercise alone are unlikely to overcome this pronounced failure of activation. Early interventions focused at improving quadriceps femoris muscle voluntary activation may improve efforts to restore muscle force.

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