Effect of muscle tendon vibration on the perception of force

The effect of vibrating the biceps muscle tendon on the perception of forces exerted by the elbow flexor muscles was examined during briefly maintained, submaximal contractions. Subjects were required to estimate the perceived magnitude of isometric forces exerted by the elbow flexor muscles under normal conditions and during vibration of the right biceps tendon. The matching forces produced by the unperturbed left arm provided an estimate of the perceived intensity of the reference arm contraction. Both force and the brachial biceps and triceps EMGs were recorded from each arm. In comparison with the matching forces produced under normal conditions, there was a significant overestimation of the forces exerted by the vibrated biceps muscle. This increase in the perceived intensity of the reference force was associated with an increase in the EMGs of the biceps and triceps muscles of the reference arm. It appeared that during vibration the triceps muscle was cocontracting presumably as a means of controlling the reference force. The overestimation of the forces exerted by the vibrated muscle could therefore reflect either the enhanced excitatory drive required to overcome the antagonist activity, or the concomitant increase in the force generated by the agonist muscle. Previous results suggest that the former is the more probable explanation.