the shake weight produce a slight burn after you use it , but it should not replace a dumbell set . man and woman would have toner and stronger arm if they invest they money and effort into a set of dumbell . even just a pair of dumbell at a comfortable weight allow you to do more excercise than the shake weight due to the shake weight limited motion . I beleive the majority of the people that rate this item so high be because they have never actually use a pair of dumbell before in they life , thus they think the shake weight be a effective piece of equipment , which be really be not . however , use the shake weight be better than do nothing at all , and minimal result be better than no result at all .