Assessment of Abdominal Muscle's Maximal Force of Contraction Using Surface EMG in Inguinal Hernia Patients

Introduction: Reduction in abdominal muscle's strength has been implicated in the development of inguinal hernia. Patients with inguinal hernia on one side are shown to be at higher risk of developing inguinal hernia on the other side. Aim: To assess the abdominal muscle strength in inguinal hernia subjects using surface Electromyography (EMG) and compare it with healthy controls. Materials and Methods: This is a cross-sectional study involving only male subjects. Abdominal (Inguinal) hernia subjects without any known complications were recruited from surgery department and the accompanying healthy individuals were taken as control (Control, n=44, inguinal hernia subjects, n=43). The subjects were asked to perform maximal contraction for three seconds targeting external and internal oblique muscles of right and left sides separately. Motor unit potentials were recorded using surface EMG for individual muscles on both sides during maximal contraction. The maximum amplitude of the motor unit potentials obtained was considered as the strength of the respective muscle. Results: In control group, there was no significant difference in strength of external and internal oblique muscles between the two sides. Strength of external and internal oblique muscles of both herniated and unaffected side was reduced in inguinal hernia subjects as compared to healthy controls. Further, the muscle strength of herniated side was less as compared to unaffected side in the inguinal hernia subjects. Conclusion: Abdominal muscle strength is reduced in hernia subjects and even the apparently normal side strength is less as compared to controls. This should be considered while performing corrective surgeries in inguinal hernia subjects.