The effects of muscle conditioning on movement detection thresholds at the human forearm

Abstract

We have used the muscle history dependence of the sensitivity of muscle spindles to stretch, to provide evidence for their contribution to kinaesthesia, the sense of position and movement. Stretch sensitivity is altered depending on whether or not slack has been introduced in intrafusal fibres. At the human elbow joint detection threshold was measured to passive movements applied at different speeds to the forearm after a conditioning co-contraction of muscles of the upper arm, with the arm held either flexed ('hold short') or extended ('hold long'). Test measurements were made with the elbow joint at 90°. For the three speeds of movement, 2° s-1, 0.2° s-1 and 0.02° s-1, after 'hold short' c..