Related Experiment Video
Updated: Jun 20, 2026
Assessment of Neuromuscular Function Using Percutaneous Electrical Nerve Stimulation
Published on: September 13, 2015
Reliability and interpretation of single leg stance and maximum voluntary isometric contraction methods of
Marc F Norcross1, J Troy Blackburn, Benjamin M Goerger
1Neuromuscular Research Laboratory, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-8700, USA. norcross@email.unc.edu
Abstract:
Normalization of electromyographic (EMG) amplitudes is necessary in the study of human motion. However, there is a lack of agreement on the most reliable and appropriate normalization method. This study evaluated the reliability of single leg stance (SLS) and maximal voluntary isometric contraction (MVIC) normalization methods and the relationship between these measures for the gluteus maximus (GMax), gluteus medius (GMed), rectus femoris (RF), vastus lateralis (VL), hip adductor group (ADD), and biceps femoris (BF). Surface EMG was recorded in 20 subjects during three 5s trials of SLS and MVIC. SLS and MVIC methods both demonstrated good-to-excellent reliability in all muscles (ICCs>0.80). Intrasubject coefficients of variation were lower for the MVIC method (9-36%) than for the SLS method (20-59%). EMG amplitudes during MVIC and SLS were significantly correlated for all muscles (Pearson r's=0.604-0.905, p<0.005) except GMax (r=0.250, p=0.288). Use of SLS normalization for the RF, VL, and BF is not recommended due to a lack of measurement precision. However, this method is justified in the GMax, GMed, and ADD and may provide a better representation of coordinated muscle function during a functional task.
