Evidence from proprioception of fusimotor coactivation during voluntary contractions in humans

摘要: In experiments on position sense at the elbow joint in horizontal plane, blindfolded subjects were required to match of one forearm (reference) by placement their other arm (indicator). Position errors measured after conditioning muscles reference with an isometric contraction while was held either flexed or extended. The difference two forms large when conditioned remained relaxed during matching process and it became less lift a load (10 25% maximal voluntary contraction, respectively). Errors from muscle attributed signals arising spindles hypothesized result thixotropic property passive intrafusal fibres. Active does not exhibit thixotropy. It is proposed that are less, because become coactivated through fusimotor system. distribution therefore seen be reflection recruitment thresholds. For flexors most, but all, fibres appear recruited 10% contraction.