title: Passive and active lower-limb movements delay upper-limb balance reactions.
abstract: This study investigated the influence of rhythmic lower-limb activity on the timing of upper-limb balance reactions. Compensatory grasping reactions were evoked in healthy subjects by rapid sagittal tilts of a chair under three conditions: (1) active leg pedaling, (2) passive (motor-driven) leg pedaling, and (3) no lower-limb movement (control task). Compared with control trials, both active and passive pedaling resulted in similar delays in the initiation (43-47 ms) and execution (12-17 ms) of grasping reactions. The similarity between effects due to active and passive movement suggests that the conditioning arose predominantly from sensory discharge associated with lower-limb movement. These results may have important implications for understanding the influence of locomotion or other ongoing movement on the control of stability.
authors.affiliation: Graduate Department of Rehabilitation Science, University of Toronto, 256 McCaul Street, Toronto, Ontario M5T 1W5, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Quant
authors.forename: B E
authors.initials: BE
authors.lastname: Maki
authors.forename: M C
authors.initials: MC
authors.lastname: Verrier
authors.forename: W E
authors.initials: WE
authors.lastname: McIlroy
mesh_terms: D000328:Adult; D000344:Afferent Pathways / Q000502:physiology; D001132:Arm / Q000294:innervation / Q000502:physiology*; D002490:Central Nervous System / Q000502:physiology*; D005246:Feedback / Q000502:physiology; D005260:Female; D005684:Gait / Q000502:physiology*; D006181:H-Reflex / Q000502:physiology; D018737:Hand Strength / Q000502:physiology; D006801:Humans; D007866:Leg / Q000294:innervation / Q000502:physiology*; D008124:Locomotion / Q000502:physiology; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology; D009431:Neural Conduction / Q000502:physiology; D009433:Neural Inhibition / Q000502:physiology; D010507:Periodicity; D004856:Postural Balance / Q000502:physiology*; D011434:Proprioception / Q000502:physiology; D011930:Reaction Time / Q000502:physiology*