What is the best method to assess the abdominal wall? Restoring strength does not mean functional recovery

BACKGROUND: Restoring the contractile function to the abdominal wall is a major goal in hernia repair. However, the core understanding is required when choosing the method for outcome assessment. AIM: To assess the role of the anterolateral abdominal muscles on abdominal wall function in patients undergoing hernia repair by analysis of correlation between the surface electromyography activation signal of these muscles and torque produced during validated strength tests. METHODS: Activation of the rectus abdominis, external oblique, and internal oblique/transverse abdominis muscles was evaluated by surface electromyography during two validated tests: Step: 1-A, isometric contraction in dorsal decubitus; 1-B, isometric contraction in lateral decubitus; 2-A, isokinetic Biodex testing; and 2-B, isometric Biodex testing. RESULTS: Twenty healthy volunteers were evaluated. The linear correlation coefficient between root mean square/peak data obtained from surface electromyography signal analysis for each muscle and the peak torque variable was always <0.2 and statistically non-significant (p<0.05). The agonist/antagonist ratio showed a positive, significant, weak-to-moderate correlation in the external oblique (Peak, p=0.027; root mean square, 0.564). Surface electromyography results correlated positively among different abdominal contraction protocols, as well as with a daily physical activity questionnaire. CONCLUSIONS: There was no correlation between surface electromyography examination of the anterolateral abdominal wall muscles and torque measured by a validated instrument, except in a variable that does not directly represent torque generation.