Prolonged infrapatellar tendon vibration does not influence quadriceps maximal or explosive isometric force...

The influence of muscle/tendon vibration on maximal muscle performance is unclear. This study examined the effect of a prolonged tendon vibration stimulus on maximum voluntary contraction (MVC) and explosive voluntary contraction (EVC) performance.

Eighteen young healthy males (nine strength trained and nine untrained) completed a series of isometric unilateral knee extensions (EVCs, electrically evoked octet responses, MVCs, ramp contractions) pre and post two separate 30-min intervention trials; infrapatellar tendon vibration (80 Hz), and quiet sitting (control). H max and M max were measured at the start and end of each series of contractions, both pre- and post-intervention (i.e., at four time points). Knee extensor force and both quadriceps and hamstrings EMG were measured throughout each series of contractions.

Vibration had no effect on either maximum force (ANOVA, trial × time interaction P = 0.92), explosive force (P ≥ 0.36), or the associated agonist EMG amplitude during these tasks (P ≥ 0.23). Octet responses were also unaffected by vibration (P ≥ 0.39). Conversely, post-intervention H max/M max was 60 % lower in the vibration trial vs. control, and remained 38 % lower at the end of the post-intervention measurements (t test, both P < 0.01). Individual H max/M max depression did not correlate to changes in either maximum or explosive force (Spearman's Rank, P ≥ 0.54), and training status had no influence on the effect of vibration.

Prolonged infrapatellar tendon vibration depressed H-reflex amplitude, but did not affect either maximal or explosive isometric force production of the quadriceps.