The Effect of Unstable Support Surface Changes on Upper and Lower Limbs on Core Stabilizing Muscle Activation during Plank Exercise

Purpose: This study aims to suggest effective exercise methods for individual situations by examining changes in trunk muscle activity when plank exercise is performed using unstable support surfaces for the upper and lower limbs, respectively.Methods: Thirty-six adult males were divided into 3 groups.The subjects were divided into three groups of 12 people through a lottery.The first group was the standard plank group (Plank), the second group was the Upper Unstable Plank group (UUP), which provided instability to the upper extremities, and the third group was the Lower Unstable Plank group (LUP), which provided instability to the lower extremities.To compare the activity of trunk muscles during each plank movement, EMG was used to compare the muscle activity of the external oblique (EO), rectus abdominis (RA), and erector spinae (ES) muscles.Muscle thickness of the transverse abdominis (TrA) was measured using ultrasound.Results: This study showed that mean muscle activity of EO and RA was significantly increased in the UUP and LUP groups compared to the Plank group (p< 0.05).ES was not significantly different among the three groups.The mean muscle thickness of TrA was significantly increased in LUP (p< 0.05). Conclusion:According to the results of this study, when providing instability in the plank posture to enhance trunk stability, it is recommended to provide instability to the lower extremities rather than the upper extremities.