Electromyography activity of the rectus abdominis during an exercise performed with the ab slider

Strengthening of abdominal muscles is often used in athletic training and in clinical rehabilitation of subjects with low back pain. Traditionally, it is performed by isometric or concentric abdominal contractions in supine position. Recently, the AB Slider has been introduced as a device to train abdominal muscles in quadrupedic position. The aim of this study was to assess the muscle activity and the type of contraction of the rectus abdominis while performing an exercise with the AB Slider and to compare it to a crunch exercise (CE). Sixteen subjects were trained to correctly perform both exercises. Muscle activity of the rectus abdominis was assessed using surface electromyography, and a stereophotogrammetric system Elite was used for the kinematic analysis. During exercise on the AB Slider, knee extension was 51.3°±9.1° (mean±SD) and the distance between the pelvis and the xiphoid process always increased. During CE, rectus abdominis activity was 73.4%±23.5% of the maximal voluntary (MVC) and during the AB Slider exercise it was 96.2%±23.0% of MVC (p=0.011, Wilcoxon's test). During the exercise with AB Slider, there was greater activation of the rectus abdominis muscle than during CE. Kinematic analysis indicated that the activity occurs in eccentric conditions. The AB Slider seems to be a good device for strengthening the abdominal muscles.