CORE STABILITY MUSCLE ACTIVITY DURING STANDING LOWER BODY TWISTING EXERCISES.

Background: Little is known about the activity of the abdominal internal oblique (IO) and lumbar multifidus (LM) muscles relative to kinetic chain exercises performed in a standing position. Hypothesis/Purpose: The purpose of this study was to identify the activity of the IO and the LM muscles during weight-bearing exercises. The authors hypothesized that IO and LM muscle activity would vary with lower body positions during the kinetic chain exercises. Methods: Nineteen healthy, young, active subjects volunteered to participate. The electromyographic (EMG) activity (via surface EMG) of the abdominal external oblique (EO), IO, and LM muscles on both sides and the rectus femoris and semitendinosus muscles on the dominant side was determined during rhythmical lower body twisting exercise with three lower body positions: straight leg (SL), athletic position (AP), dynamic knee extension (DE) at two exercise speeds: 150 and 90 beats per min. These were reported as % maximum voluntary contraction. Mean EO, IO, and LM muscle activities were also compared with those of common core stability exercises. Results: IO EMG activity was significantly greater in SL than that of AP (p < 0.05). In contrast, LM EMG activity was significantly greater in the DE position than that of both SL and AP positions (p < 0.05). Conclusion: IO muscle activity could be attenuated by the contraction of lower body extensor muscles during the standing position. Level Of Evidence: Basic Laboratory Study, Level 3b [ABSTRACT FROM AUTHOR]