Visual perception modulates motor output of manual therapy thrust delivery


Vision is the predominant sensory modality informing motor output. Perception through vision may lead to motor changes in decision making when scaling output generated by clinicians who deliver manual therapies. The present study examined the effects of various life-sized, human-shaped, visual stimuli on kinetic and kinematic characteristics of spinal manipulative thrusts delivered by experienced chiropractors (n=8) to a low fidelity model. Sex, height, and body mass index (BMI) of the stimuli were varied across trials in a randomized order (6 trials per stimulus, 108 trials per participant). Instrumentation recorded at 300Hz for 5 seconds during each trial and included a force transducer between the clinician's hand and the model, an accelerometer, and an infrared emitting diode on the clinician's distal ulna. Dependent variables included thrust force, thrust duration, displacement, peak acceleration, and time to peak acceleration (TTPA) of the thrust. Three-way repeated measures ANOVA models were used to analyze dependent measures, followed by Tukey's HSD to compare significant effects. Sex of the visual stimuli had a significant effect on thrust force (female