Response of human muscle spindle afferents to abrupt load perturbations

Response patterns of single muscle spindle primary afferents to abrupt load perturbations inflicted upon the contracting finger flexors were investigated in awake human subjects using the technique of microneurography. Units showed a transient high-frequency discharge in the rising phase of the stretch. No repeated burst activity attributable to irregularities of the stretch velocity or to mechanical oscillations of the muscle could be detected.