Vibration training is a relatively recent trend in the strength and conditioning field which the Shake Weight is attempting to adapt to general consumer fitness. The theory behind vibration training is that the frequency of the oscillations of the equipment stimulate the muscle spindles (a sensory mechanism within a muscle which respond to changes of length within that muscle) which ultimately provides a higher force output during muscle contraction. Most of the research literature has focused on methods of whole body vibration training with some mixed results as to whether the frequency of the stimulus actually leads to greater levels of muscle force production. The idea behind the Shake Weight is that the movement of the mass stimulates the muscles to work harder during the actual resistance-training exercises.
It is necessary to provide a little bit of science on how the body adapts to resistance training to properly explain why the Shake Weight is not an effective product. The body has different types of muscle fibers; the muscle fibers responsible for muscle “tone” are the type II fibers which are stimulated by greater amounts of resistance or muscle force production. The common myth of using a light weight with a high volume of repetitions to create muscle “tone” is inaccurate. Using a light weight for high repetitions will make the muscle more effective at using oxygen to create energy but does not provide the necessary stimuli to provoke growth in the type II fibers responsible for definition. If an individual wants to perform resistance training in an effort to develop more muscle definition without a concurrent increase in muscle fiber size it is necessary to use a load heavy enough to fatigue the muscle within 4-8 repetitions. Another option for developing muscular definition without an increase in muscle fiber size is to perform explosive exercises like plyometric jumps or sprints. The real reason why many celebrities are able to lose weight and increase their muscle definition during televised dance contests is because they are performing a high volume of explosive exercises as they learn the choreographed dance routines.
The Shake Weight video demonstrates how to use the weight which is to first shake it for a period of time, then perform a standard resistance training exercise. In theory the oscillations of the weight should stimulate extra muscular activity during the exercise but in practice the weight is somewhat difficult to use to shake properly and the light resistance does not provide enough of an overload to make it an effective tool for developing strength or muscular definition. Plus, the video only demonstrates one set of each exercise which, generally speaking, is not enough of an overload on the muscles to provoke the specific adaptations of improved strength or muscle definition. Additionally the exercise selection demonstrates a chest exercise which does not provide an effective use of the pectoralis major (chest) muscle. To properly train any muscle (in this case the chest) the line of pull of the resistance must be parallel to the orientation of the muscle fiber, the exercise demonstrated has the resistance perpendicular to the orientation of the fiber which does not provide the necessary stimulus.
An effective exercise program includes cardiovascular training for energy expenditure along with flexibility training to improve muscle length and joint range-of-motion, therefore, another issue with the Shake Weight is that the accompanying DVD demonstrates a workout for the upper body only. If an individual does an exercise routine for the smaller muscles of the upper body, they will not expend nearly as many calories as if they are doing exercises with all of the muscles of their body, and while the DVD does demonstrate some basic stretches for the chest and shoulders, it does not provide any stretches for the muscles of the legs, back or hips where most of the muscle mass of the body is located.
If a fitness enthusiast is looking for a product to increase their muscle definition he or she would be much better served by looking for exercise videos which demonstrate fun, dynamic routines that including jumping or dancing.
What we liked:
- A visually detailed DVD which demonstrates a simple exercise program that can be performed in only six minutes.
What we didn't like:
- The limited number of exercises demonstrated in the DVD; one set of exercises with a light weight does not provide enough physiological demand to create the adaptations advertised on the product’s website.
- The weight can be difficult to shake to provide the necessary stimulus.
- The mass of the weight is too light to provide the necessary adaptations for strength and muscle tone.
- The exercises demonstrated in the DVD are not effective for developing strength or definition in the chest.
June 15, 2010