Effect of knee angle on neuromuscular assessment of plantar flexor muscles: A reliability study

Introduction This study aimed to determine the intra- and inter-session reliability of neuromuscular assessment of plantar flexor (PF) muscles at three knee angles. Methods Twelve young adults were tested for three knee angles (90 degrees, 30 degrees and 0 degrees) and at three time points separated by 1 hour (intra-session) and 7 days (inter-session). Electrical (H reflex, M wave) and mechanical (evoked and maximal voluntary torque, activation level) parameters were measured on the PF muscles. Intraclass correlation coefficients (ICC) and coefficients of variation were calculated to determine intra- and inter-session reliability. Results The mechanical measurements presented excellent (ICC> 0.75) intra-and inter-session reliabilities regardless of the knee angle considered. The reliability of electrical measurements was better for the 90 degrees knee angle compared to the 0 degrees and 30 degrees angles. Conclusions Changes in the knee angle may influence the reliability of neuromuscular assessments, which indicates the importance of considering the knee angle to collect consistent outcomes on the PF muscles.