Is gamma loop dysfunction related to bilateral inhibition in anterior knee pain?

The potential relationship between bilateral quadriceps inhibition in individuals with unilateral anterior knee pain (AKP) and gamma loop dysfunction is examined in this study.

Twelve individuals with unilateral AKP and 10 healthy controls were recruited. Quadriceps voluntary activation (%VA) was quantified using a triggered interpolated twitch technique. Gamma loop function was assessed through knee extension maximum voluntary isometric contractions before and after 20 minutes of 50-Hz patellar tendon vibration.

The AKP group exhibited 5.7% lower %VA bilaterally compared with controls (P = 0.039, Cohen d = 0.79). After prolonged vibration, both groups exhibited an average 8.5% reduction in knee extension force in each limb (P < 0.001, Cohen d = 0.85).

Significant force reductions after vibration suggest that gamma loop dysfunction was not seen in either control or AKP participants. Bilateral quadriceps inhibition in the AKP group does not appear to be associated with gamma loop dysfunction.