Mitchell, A., Ralston, J., Davies, G., & Riemann, B. L. (2014). Comparison of upper extremity muscle activation between different inertial exercise equipment. Medicine & Science in Sports & Exercise, 46(5), Supplement abstract number 2474.

"Newer modes of resistance training, such as inertial training, are becoming increasingly popular. Inertial training involves alternating concentric and eccentric muscle actions, often rapidly, to change the acceleration of a mass. Two popular inertial training devices include the Bodyblade® and Shake Weight®, with respect to the Shake Weight, little data concerning muscle activation exists."

This study compared the anterior deltoid, triceps brachii, biceps brachii, and pectoralis major (sternal and clavicular portions) muscle activity during four unilateral exercises between the Shake Weight (1.1kg), Bodyblade (.68kg), and a standard dumbbell (.90kg). During a single session, physically active females (N = 17; 23.6 ± 2.0years) completed four oscillation exercises with each device. The exercises selectively targeted the anterior deltoid, triceps brachii, biceps brachii, and pectoralis major-sternal/pectoralis major-clavicular muscles by varying the positions of the shoulder and elbow. Ss oscillated the devices in each position for 30 seconds. The device and exercise order were randomly established for each S with one minute rest between exercises and two minutes rest between devices. The mean amplitude of surface electromyographical activity and number of oscillations were computed for the middle-24 seconds.

For the muscle by device by position analysis, significant main effects for device were revealed. Muscle activation was significantly greater for the Bodyblade compared to the Shake Weight. There were no significant differences between the dumbbell and Bodyblade or Shake Weight and dumbbell. The number of oscillations for the dumbbell was significantly less compared to those for the Bodyblade and Shake Weight.

Implication. The Shake Weight failed to produce greater activation than a standard dumbbell and less activation than the Bodyblade. The Bodyblade is recommended for promoting the greatest muscle activation during unilateral oscillatory exercises. The greatest muscle activation in all positions was produced by the Bodyblade and the dumbbell. The anterior deltoid was the greatest activated muscle in all three forms of equipment proving that it has a stabilizing role during the exercises. That emphasizes the important role the anterior deltoid has on shoulder function and exercises.

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