Several EMG studies have been performed in the past decade to quantify and validate claims of “core stability” exercises. Despite few controlled, clinical outcome studies on using an exercise ball, its use in clinics and gyms remains steady. Because the Thera-Band® exercise ball can be used for both rehabilitation and fitness, different exercises and levels of muscle activation may be best for specific patients and clients. It’s important to know that an exercise provides enough EMG activation for strength training (greater than 60% maximal contraction), or if it’s more endurance-based (less than 25%).
In an article published in the Journal of Strength and Conditioning Research, researchers were interested in determining the EMG levels of ‘advanced’ exercises using an exercise ball. The authors noted that most exercise ball EMG studies have evaluated basic exercises, finding few exercises with a ball that activate core muscles more than traditional resistance exercises at training effect levels.
In the study, 14 healthy subjects performed 6 advanced exercises in random order. The exercises involved were more “whole-body” movements compared to traditional stabilization exercises focusing on the core. Surface EMG data was collected from the upper body (deltoid, pectoralis major, triceps), core (lumbar extensors, rectus abdominus, external oblique), and lower body (vastus lateralis, biceps femoris).
The best abdominal exercise was the prone roll-out (“bridge”), activating the rectus abdominus at 61% maximal contraction (MVIC). The erector spinae were activated most during the “rolls” exercise at 54%; the rolls exercise also elicited the most upper body and lower body EMG levels: pec major (41%), deltoid (38%), triceps (73%), vastus lateralis (84%), biceps femoris (54%).
The authors concluded that the prone roll-out was the only exercise capable of eliciting muscle activity levels associated with a training effect for the rectus abdominus. They suggested that advanced ball exercises activate at low to moderate levels, well below the muscle “activity levels of moderately loaded conventional resistance exercises such as bench-press, squat, and deadlift.” These findings suggest the exercise ball may be more effective for stabilization and endurance activities rather than strength training. It’s important for clinicians and fitness professionals to choose the appropriate tool for the appropriate outcomes.
REFERENCE: Marshall PW, Desai I. Electromyographic analysis of upper body, lower body, and abdominal muscles during advanced Swiss ball exercises. J Strength Cond Res. 2010 Jun;24(6):1537-45.