Influence of Difficulty Variation of the Core Stabilization Exercise on Thickness Changes of Abdominal Muscles in Healthy Subjects: A Pilot Study

Abstract

Purpose: This study examined thickness changes in abdominal muscles according to difficulty level of core stabilization exercise in healthy subjects. Methods: Thirty healthy subjects (age range: 21-30 years) volunteered under three conditions. In the first condition, the subjects performed an abdominal draw-in maneuver (ADIM). In the second condition, they performed the ADIM during quadruped exercise using a suspension device without extending their lower limbs. In the third condition, the subjects performed the ADIM during quadruped exercise using a suspension device while extending both lower limbs. The changes in thickness of transverse abdominis (TrA), internal oblique (IO), and external oblique (EO) muscles were measured by ultrasonography (US) imaging during the three experimental conditions, and US was used to measure the improvement ratio of muscle thickness at rest. The interventions were conducted over three trials in each condition, and measurements were performed on each subject by one examiner. Results: Our results showed a significantly greater increase in the muscle thickness of TrA and IO muscles after performance of quadruped exercise using a suspension device without knee extension (p< 0.05) compared to the other conditions. The results also showed a significantly greater increase in the thickness changes of EO muscle in those who performed the ADIM during quadruped exercise using a suspension device with knee extension (p< 0.05) compared with the ADIM only. Conclusion: These findings demonstrated positive evidence that a low-level core stabilization exercise could improve thickness of abdominal muscles.