Independence of skeletomotor and fusimotor activity in man?

The activity of human muscle spindle afferents from finger extensor muscles has been studied during voluntary movements in a visual tracking paradigm. With an elastic load the spindle discharge rate was disproportionately high when the opposing force was close to zero, suggesting that the fusimotor drive was high when the direct afferent information about the size of the load that the subject had to handle was poor.