Electromyographic Analysis of Hip Muscle Activity Comparing Maximal Voluntary Contraction to Manual Muscle Test Grades

Introduction: The purpose of this study was to investigate the relationship between muscle activity during three manual muscle tests (MMT) and muscle activity during a maximal voluntary contraction (MVC) of the same muscle. Subjects: Eleven female subjects voluntarily participated in this study. All participants were physical therapy students under the age of 30, nonpregnant, and without recent history of musculoskeletal injury. Methods: Electromyographic (EMG) data was collected by placing surface electrodes over each participant\u27s right tensor fasciae latae (TFL) and gluteus medius (GM) muscle. The EMG data from each muscle was transmitted by Noraxont TeleMy02400 G2 telemetry to a computer equipped with MyoResearch XP 1.07 software. EMG data was collected while each participant performed a MVC and a Normal (5), Fair (3) , and Poor (2) Grade MMT test for each muscle, respectively. Results: EMG data analysis produced an average percentage of MVC for MMT of GM and TFL using Grades 5, 3, and 2 as follows: 91.7%; 32.3%; 20.7%. Conclusion: This study shows the percentage of MVC EMG activity elicited by MMT of Grades 5, 3, and 2 for TFL and GM. These percentages could possibly be used by clinicians as an inferred benchmark of muscle activity elicited by patients achieving these MMT scores; referenced as a percentage of MVC in normal functioning muscle