Non-invasive Vibratory Stimulation of the Knee Muscles for the Improvement of the Somatosensory Input and Motor Performance

Condition(s) studied

Investigational drug(s) / intervention(s)

Vibratory stimulation: A vibratory stimulator will be applied to the back of the dominant leg, at the level of the hamstring muscle tendons. The stimulator consists of two small vibrating boxes fixed to the leg by means of an elastic band.

Study summary

The goal of this interventional cross-sectional study is to evaluate motor responses to non-invasive vibratory stimulation applied to the hamstring muscle tendons in healthy individuals. Knee flexion and extension efforts, in both isometric and concentric contractions, will be tested.

The investigators hypothesize that vibratory stimulation causes an increase in activity in the flexor muscles (hamstrings) and a decrease in the extensor muscles (quadriceps) of the knee in all motor tasks. It follows that during knee flexion (both concentric and isometric), vibratory stimulation should cause an increase in the distance between the angular trajectories of the knee obtained with and without vibratory stimulation (with a positive sign). The increased activity of the hamstring muscles would, in fact, contribute to increasing the velocity of the flexor movement. Conversely, during extensor movements (both concentric and isometric), vibratory stimulation should reduce the instantaneous velocity of the movement, therefore causing an increase in distance (with a negative sign) between the trajectories obtained with and without stimulation.

Participants will be tested using an isokinetic dynamometer and they will be asked to perform the following motor tasks in a random order: concentric knee flexion, concentric knee extension, isometric knee flexion, and isometric knee extension. The dominant limb will be tested, only. The assessment will be performed one time.

Eligibility

Primary outcome measure(s)

• Knee angle — Day 1.
  Maximum distance (in degrees) between the knee trajectory obtained with and without vibratory stimulation.
• Surface electromyography (sEMG) — Day 1.
  Difference in sEMG between the muscle activity with and without vibratory stimulation, for each muscle (i.e., Quadriceps, Hamstrings, and Plantarflexor muscles).

Trial sites (1)

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