10/12/2016
Motion and muscle activity are affected by instability location during a squat exercise.
Nairn, Brian C. MSc; Sutherland, Chad A. MSc; Drake, Janessa D.M. PhD
Published Ahead-of-Print
Collapse BoxAbstract
Squat exercise training using instability devices have become increasingly popular for a multitude of reasons. Many devices generate instability at the feet and provide a bottom-up perturbation; however, the effect of a top-down instability device during a squat remains unclear. In order to induce instability at the upper body, a water-filled cylinder called the Attitube(R) was used. This study analyzed the effects of instability location (top-down, bottom-up, no instability) during a squat exercise in terms of kinematics and muscle activation. Ten male participants were instrumented with 75 reflective markers to track kinematics of the ankle, knee, hip, trunk, and the Bar/Attitube(R); and electromyography was recorded from 12 muscles bilaterally. Squats were performed with an Olympic bar on a stable surface, Olympic bar on a BOSU(R) ball (BALL, bottom-up), and the Attitube(R) on solid ground (TUBE, top-down). The TUBE showed up to 1.5 times reduction in erector spinae activation and up to 1.5 times less trunk flexion while being performed at a slower velocity. There was also higher abdominal activation in the TUBE, with up to 2.8 times greater oblique activation compared to the stable condition. The BALL increased ankle eversion and knee flexion with higher muscle activation in gastrocnemius, biceps femoris, and quadriceps. Overall, changing the location of instability during a squat changed the motion and muscle activation patterns of the trunk and lower extremities. This provides information for future research into rehabilitation, learning proper squat technique, and for specific training scenarios.
Copyright (C) 2016 by the National Strength & Conditioning Association.
