A giant set entails doing 3 or more exercises in a row without rest. It is the bigger brother of the super set, which involves doing two exercises in a row without rest. Typically in a giant set you do about 10 reps of each exercise, rest less than 60 seconds and then move on to the next exercise. It works best for exercises that stimulate muscles in different ways but for the same body part.
Since you are doing a high number of reps and resting so little you cannot use as heavy a weight. For example if you were doing a giant set on the chest you could start by doing the flat bench, followed by the incline bench and lastly the decline bench. All three exercises target the chest but hit mid chest (flat bench), the upper chest (incline bench) and the lower chest (decline bench).
Giant sets are not recommended for beginners. You should have at least 18-24 months of weight training experience before attempting a giant set.
Two Divergent Schools Of Thought
If you asked a hundred bodybuilders what they thought about giant sets, about half will look at you funny and smack you in the face because you don’t know what you are talking about! The other half will get excited and proclaim that giant sets are the best thing since sliced bread.
If you’ve read anything I’ve written in the past you know that I recommend training with heavy weights (as heavy as you can) and short intense workouts. I am also a big proponent of progressive overload which is when you increase the amount of weight you do for each exercise gradually as you build strength, usually over a period of weeks. Lastly, I’m an advocate of resting however long it takes to be able to bring the most intensity to bear on your next exercise.
Giant sets fly in the face of all of this since they involve lifting lighter weights, doing lots of reps and resting under sixty seconds, by virtue of which you will not be able to train as intensely.
Given all this I personally think giant sets are completely useless for stimulating muscle growth.
Those who believe in them usually cite the fact that they force blood flow into the targeted areas and shock the muscles into growth, catching them by surprise. This is complete hogwash. The muscles do not have a mind of their own and you cannot catch them by surprise. They only respond to intensity, however you are able to trigger it.
Very often overly commercial trainers use giant sets for marketing purposes so that what they are doing can sound ‘revolutionary’. “Shock Your Muscles To Growth!” or “Maximum Muscle Confusion Revealed!” are some of the catchy phrases I’ve seen used.
That said, giant sets have a place in building endurance and stamina. I know some martial artists who use them to build up mental discipline. The difficulty of completing them makes it tempting to quit and so carrying on to the end is good preparation for a long fight where an opponent may dominate you if you do not have sufficient stamina/mental fortitude to persist in spite of the painful blows.
I won’t stop you from doing giant sets but just be very clear about your goal. If you want to build endurance use them by all means but if you want to build muscle, I hate to be the one to tell you this bro: You are wasting your time!