Basically, a monster set is performing consecutive smaller sets of an exercise until you reach a large, predetermined number like 50 or 60 reps. To perform monster sets, you should select an amount of weight that is 65% of your one-repetition maximum. This should enable you to do about 15 reps in the first smaller set. Once you reach failure, take a quick rest. Then keep going until you reach your goal.
For example, let’s say that your one-rep max on the bench press is 150 lbs. That means you’ll probably want to use about 100 lbs of resistance for your monster set. Ideally, you’ll be able to do 15 reps in the first set. Take a quick break, then continue for another set. Maybe you can get 10 or 12 reps out of that set. Rest, and then continue. Maybe you get 8 reps. And so on until you reach 50 or 60.
Though monster sets shouldn’t be the backbone of your workout, they’re a great way to occasionally mix things up and really shock your muscles.