Traditionally drop sets are only used on the last working set of an exercise. During the first few working sets you should be pushing yourself to the limit, so performing a drop set too early will jeopardize how much weight you will be able to lift for following sets.
How to perform a drop set:
Exercise Example - Standing DB Bicep Curls
Perform a full set of 12 reps, rack the DB’s, pick up another pair between 20-30% lighter. Start performing reps again with this lighter weight until failure, rack the DB’s, then once again go for another set of DB’s 20-30% lighter and go to failure once more.
Rest Pause Set
A rest pause set will consist of three short 20 second breaks within the set. The idea is to keep the same throughout the whole set and allow the 20 seconds to help you recoup and get some extra reps out.
Exercise Example – Lying Hamstring Curl
First Set - 12 reps @ 40kg
20 seconds rest
Second Set – 10 reps @ 40kg
20 seconds rest
Third Set - 8 reps @ 40kg
Again, another method I like to include on a final set of an exercise is Isometric holds. Iso holds create an incredible amount of intra muscular damage and elevated levels of lactic acid dramatically.
Exercise Example – Leg Extension
Perform your final set as usual to failure, and on the last rep squeeze the weight up to the top of the movement and hold it there for a set amount of time (I use 10 seconds). If you have a trainer or a training partner, get them to push weight down against you and resist the pressure.
Here you will perform 6 sets of 4 reps and only have 10 seconds rest in between the sets, keeping the weight the same for each set. The weight you should choose will be what you can do for 15 reps of that chosen exercise. By the 5th set you should be grinding the reps out and the 6th set should feel barely doable. Don't go up in weight on the muscle round until you complete all 6 sets.