Statistical analysis
SECONDARY, POSTERIOR
EMG amplitude was assessed under four conditions (DB, ELECTRO, VR, EO) at five joint angles (30°, 50°, 70°, 90°, 110°) for both concentric and eccentric actions. The preregistered analysis for this study intended to employ a frequentist approach with a focus on interpreting the results on a continuum using all statistical outcomes in combination with theory and practical considerations. Prior to any analysis of data collected, however, it was decided that a Bayesian approach better matched the overall intention, which was to explore potential differences in myoelectric activity and assess the extent to which they may be meaningful rather than dichotomize results. In addition, Bayesian analyses with their sampling procedures provide a relatively simple tool to model extensive repeated measures structure within data. In the interests of transparency, we conducted statistical analyses using both approaches and have presented the original methods and results from the preregistered approach in supplementary files (see Supplemental Table The primary analysis comprising Bayesian mixed effects models were conducted separately for each muscle and phase of movement (concentric or eccentric), with data combined across joint angles and repetitions. Mixed effect models included: (1) fixed effects for condition, joint angle and repetition; (2) random effects for participant intercepts; and (3) an autoregressive ar(1) term to account for stronger associations between adjacent repetitions. Fixed effects for condition were set by including DB as the reference level such that a positive/negative coefficient indicated increased/reduced EMG activity for the comparator (ELECTRO, VR or EO). Inferences on population mean differences in EMG activity between the conditions were made using the posterior samples from fixed effects and interpreting median values and 95% credible intervals (95% CrI’s). Posterior samples were also used to calculate the probability that differences exceeded the pre-determined thresholds of 0, 5 and 10%MVIC to better interpret the practical significance of results. The secondary analysis was conducted using the same mixed effects models but separated across joint angles with results presented in the supplementary files (Table Default priors were used for all parameters including improper flat priors (any value is considered equally likely), the LKJ(1)-correlation prior