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Updated: Mar 9, 2026

Bilateral Assessment of the Corticospinal Pathways of the Ankle Muscles Using Navigated Transcranial Magnetic Stimulation
Published on: February 19, 2019
Vastus medialis and lateralis activity during voluntary and stimulated contractions
Rosa M S Visscher1, Diego Rossi1, Bernd Friesenbichler1
1Human Performance Lab, Schulthess Clinic, Lengghalde 2, 8008, Zurich, Switzerland.
Introduction:
The purpose of this study was to investigate the relative activation of vastus medialis (VM) and vastus lateralis (VL) muscles during voluntary and stimulated isometric contractions at different joint angles.
Methods:
Sixteen healthy men (mean age: 26 years) completed maximal voluntary and stimulated contractions of the knee extensor muscles at 30°, 65°, and 100° of knee flexion. VM/VL ratios were calculated from voluntary electromyographic (EMG) and evoked torque recordings.
Results:
Both EMG and VM/VL torque ratios were significantly lower at 30° than at 100° of knee flexion (P < 0.05).
Conclusions:
These results can be explained by the relatively small contribution of the VM muscle to knee extension torque at short muscle length. Such disadvantage of the VM muscle at extended knee positions does not seem to be compensated by an increased neural drive. Muscle Nerve 56: 968-974, 2017.
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