Muscular Outputs During Dynamic Bench Press Under Stable Versus Unstable Conditions

Abstract

Previous studies have suggested that resistance training exercise under unstable conditions decreases the isometric force output, yet little is known about its influence on muscular outputs during dynamic movement. The objective of this study was to investigate the effect of an unstable condition on power, force, and velocity outputs during the bench press. Twenty male collegiate athletes (mean age, 21.3 +/- 1.5 years; mean height, 167.7 +/- 7.7 cm; mean weight, 75.9 +/- 17.5 kg) participated in this study. Each subject attempted 3 sets of single bench presses with 50% of 1 repetition maximum (1RM) under a stable condition with a flat bench and an unstable condition with a Swiss ball. Acceleration data were obtained with an accelerometer attached to the center of a barbell shaft, and peak outputs of power, force, and velocity were computed. Although significant loss of the peak outputs was found under the unstable condition (p < 0.017), their reduction rates remained relatively low, approximately 6% for force and 10% for power and velocity outputs, compared with previous findings. Such small reduction rates of muscular outputs may not compromise the training effect. Prospective studies are necessary to confirm whether the resistance training under an unstable condition permits the improvement of dynamic performance and trunk stability.

Instability Resistance Training Across the Exercise Continuum

“…20,24 Yet, minor deficits in force, power, and velocity (6% to 10%) occurred with a dynamic bench press performed on a physioball. 38 Less significant reductions in force with Swiss ball chest press exercises may be attributed to the compression or flattening of the ball, with higher resistance contributing to a more stable platform. 7,9,10 …”

Capillary and Venous Samples of Total Creatine Kinase Are Similar After Eccentric Exercise

“…A number of studies have documented that lower forces are produced when performing resistance activities under unstable conditions. Instability resistance training has been reported to decrease upper-(1,20) and lower-body force output (2,6,14,25) and upper- (19,20) and lower-body muscular power output (14). If strength adaptations are related to the resistance intensity (33,34), then how could instability resistance training with its lower loads still achieve similar strength results?…”

“…Furthermore, instability resistance training has been reported to decrease upper-and lower-body force output (1,4,6,25), dynamic bench press force, power and velocity (20), muscular power when utilizing an unstable pendulumlike device (19), peak concentric power and force, peak eccentric power and velocity, and range of motion (ROM) during a squat (14). Overload tension on the muscle is essential for fostering strength training adaptations (5,34).…”

Trunk Muscle Activity During Lumbar Stabilization Exercises on Both a Stable and Unstable Surface

“…11 In a separate study, performing a bench press on an unstable surface was shown to have no effect on electromyographic (EMG) recordings, although, force output was decreased. 2,13 In contrast, trunk muscle activity increased when performing a squat on an unstable surface. 1 From these findings, the influence of surface stability on muscle activity appears to be muscle and exercise dependent.…”