Related Experiment Video
Updated: Apr 16, 2026

Muscle Function Obtained with Motion Mode Ultrasound and Surface Electromyography during Core Endurance Exercise
Published on: August 25, 2022
Effects of performing an abdominal hollowing exercise on trunk muscle activity during curl-up exercise on an unstable
1Department of Physical Therapy, Graduate School, Yonsei University, Republic of Korea.
Abstract:
[Purpose] The purpose of this study was to investigate the effects of the abdominal hollowing exercise on trunk muscle activity during the curl-up exercise on an unstable surface by measuring electromyography (EMG) activity. [Subjects] Fourteen young healthy adults (nine male, five female) voluntarily participated in this study. [Methods] Each subject was asked to perform a curl-up exercise on two supporting surfaces (stable and unstable surfaces) combined with the abdominal hollowing exercise on an unstable surface. The muscle activities of the rectus abdominis (RA), external oblique (EO), internal oblique (IO), and transverse abdominis (TrA) were measured using surface EMG during performance of the curl-up exercise. [Results] The EMG activity of the RA and EO was significantly higher on an unstable surface than on a stable surface during the curl-up exercise. The EMG activities of the TrA and IO were greater in combination with the abdominal hollowing exercise on an unstable surface than during the curl-up exercise on both a stable and unstable surface. [Conclusion] These findings suggest that the local trunk muscle activity during the curl-up exercise is more strongly affected by combination with the abdominal hollowing exercise than by performance on an unstable supporting surface.
Related Concept Videos
Muscles of the Abdomen
Anterolateral Region
The anterolateral region comprises five paired muscles classified into the lateral and...
Assessment of the Abdomen II: Percussion
Percussion
Percussion is an essential...
Assessment of the Abdomen III: Palpation
Muscles of the Pelvic Floor and Perineum
Perineal Layer
The perineum is a diamond-shaped area below the pelvic diaphragm, divided into an anterior urogenital triangle that contains the external genitals and a posterior anal triangle housing the anus. The urogenital...
Abdominal Regions and Quadrants
The simpler quadrants approach, which is more commonly used in medicine, subdivides the cavity with one horizontal and one vertical line that intersects at the patient's umbilicus (navel). The four...
Exercise and Muscle Performance
Endurance exercises
Endurance exercises involve running, swimming, or cycling, which require repetitive movements with low force output. When a person engages in endurance exercise, a few noticeable changes occur in their skeletal muscles. For instance, the number of capillaries...

