Learning spinal manipulation: Gender and expertise differences in biomechanical parameters, accuracy, and variability*

Abstract

Objective: The purpose of this study was to investigate gender differences and expertise effects on biomechanical parameters as well as force accuracy and variability for students learning spinal manipulation. Methods: A total of 137 fourth- and fifth-year students were recruited for the study. Biomechanical parameters (preload, time to peak force, peak force, rate of force), as well as accuracy and variability of thoracic spine manipulation performance, were evaluated during 5 consecutive trials using a force-sensing table and a target force of 450 N. Gender, expertise differences on biomechanical parameters, as well as constant, variable, and absolute error were assessed using 2-way analysis of variance. Results: Analyses showed significant gender differences for several biomechanical parameters, as well as significant gender differences in accuracy and variability. Although women showed lower time to peak force and rate of force values, they were more precise and showed less variability than men when performing thoracic spine manipulations. Students with clinical expertise (fifth-year students) used less force and were more precise. Conclusion: Our results showed that gender differences in spinal manipulation performance exist and that these differences seem to be mainly explained by alternative motor strategies. To develop gender-specific teaching methods, future studies should explore why men and women approach spinal manipulation tasks differently.