A study of factors influencing muscle activity about the knee joint

Abstract

Several factors influencing the myoelectric activity of muscles surrounding the knee joint were studied using fine-wire monopolar electrodes. The muscles studied included the vastus lateralis, vastus intermedius, rectus femoris, vastus medialis, gracilis, sartorius, biceps femoris, semimembranosus, semitendinosus, tensor fasciae latae, medial head of the gastrocnemius, and lateral head of the gastrocnemius. Muscle activity was measured in response to unidirectional loads tending to flex and extend the knee, and to combined loads of flexion-adduction, flexion-abduction, extension-adduction, and extension-abduction. Results indicate that the individual muscle responses are dependent upon the direction, magnitude, and combination of external moments, as well as on the flexion angle of the knee joint. Muscle response appeared to be influenced by certain intrinsic mechanical characteristics of the knee joint that tend to change the moment arms of the muscles as the knee moves. For example, the substantial changes in quadriceps myoelectric activity with knee flexion, with constant load applied, can be related to the movement of the tibial-femoral contact changing the lever arm of the quadriceps mechanism. This study indicates that the mechanics of the knee joint must be taken into consideration while attempting to interpret or predict the load response of muscles crossing the knee joint.

Association between preparatory muscle activation and peak valgus knee angle

“…The role of the quadriceps and hamstrings in controlling frontal plane knee motion and loads has been established (Andriacchi et al, 1984;Hewett et al, 1996;Lloyd and Buchanan, 2001;Lloyd et al, 2005;Claiborne et al, 2006). Quadriceps and hamstrings strength has been shown to account for 13.6% and 18.1% of the variability in frontal plane motion, respectively (Claiborne et al, 2006).…”

Contributions of muscles, ligaments, and the ground‐reaction force to tibiofemoral joint loading during normal gait

“…Some investigators have also quantified the capacity of specific muscles to resist knee adduction moments during activity. [15][16][17][18][19] Lloyd and Buchanan 19 found that the muscles that produce most of the flexion-extension moment at the knee during isometric exercise (i.e., quadriceps, gastrocnemius, and hamstrings) also produce most of the moment needed to resist pure adduction. No study has identified the muscles and ligaments that stabilize the knee in the frontal plane during gait.…”

Does the presence of a vaginal probe alter pelvic floor muscle activation in young, continent women?

“…Further, the relationship between muscle activation amplitude and muscle length has not been investigated in the PFMs. In other skeletal muscles EMG activity has been found to remain consistent despite increasing or decreasing muscle length (Eloranta and Komi, 1981;Vredenbregt and Rau, 1973), but these findings are not consistent across muscles (Andriacchi et al, 1984;Lunnen et al, 1981). Mohamed et al (2002), reported that although at the most lengthened hamstring position the knee flexors produced their maximum torque, they did not find a consistent change in EMG activity with muscle length changes.…”