In bodybuilding and weight training, using drop sets is a technique for continuing an exercise with a lower weight once muscle failure has been achieved at a higher weight. It is most often performed on weight machines because reducing the weight quickly is thought by some to be extremely important, but it can also be performed with dumbbells and other free weights.
While performing a biceps curl, the person lifting the weight would start with a 25 pound dumbbell and do as many repetitions as possible without significantly compromising form. Then a 20 pound weight would be used until exhaustion is reached. One could continue to "drop" down as many times as he or she wishes, but some bodybuilders recommend using no more than three distinct weights e.g. 25, 20, 15.
There are many variations possible while using the same basic concept of reducing the weight used. One way is to do a specified number of repetitions at each weight (without necessarily reaching the point of muscle failure) with an increase in the number of repetitions each time the weight is reduced. The amount or percentage of weight reduced at each step is also one aspect of the method with much variety. A wide drop set method is one in which a large percentage (usually 30% or more) of the starting weight is shed with each weight reduction. A tight drop set would remove anywhere from 10% to 25%. These definitions are somewhat arbitrary, of course, and not everyone will agree on the exact definitions.
As it is very easy to "over train" with drop sets, it is highly recommended that no more than one to two drop sets be done per muscle group on any given workout. This technique is also not recommended as a long term regimen. The primary focus on drop setting is to "shock" the muscles by adding stress, thus incenting additional hypertrophy.
Drop sets and the technique also go by the names breakdowns, descending sets, triple-drops (when a total of three different weights are used), down the rack or running the rack (when using dumbbells), up the stack (because with a weight machine, the pin is moved up the stack of plates with each drop in weight), strip sets (when you "strip" weights off the ends of a bar), or the stripping technique (so called because of "stripping" weight plates off with each drop in weight). Drop sets where originally called The Atkin's Multiple Poundage System after Henry Atkin who discovered this system in the 1940s and written about in his 1949 article The Atkin's Multiple Poundage System by Henry J. Atkin, which can be found on the "The Tight Tan Slacks of Dezso Ban" blog, and was originally meant to be used with barbells.