Let's say you're making chili. Ingredients: ground turey, tomato puree, water chilies, assorted spices. The first three are as mild as could be. The first three ingredients are as mild as could be. But throw everything together over heat and voila you get the desired synergistic effect, seasoned and fiery, a new creation dissimiliar to any of the individual parts. The same rule applies to training. Combine three or more exercises into what is, in effect, one extended set, and the whole the whole will be unique from its parts. This is the logic behind trisets and giant sets, which create unique amalgamations of exercises. If you want to bring the heat to otherwise mild workouts, trisets and giant sets might just be the perfect recipie.
The Weider Triset Principle
While a superset consists of two exercises paired together, a triset does this one better, combining three exercises. One set of each is performed without resting between exercises, and each such three-set combination is counted as one triset. The exercises can be for the same body part (such as deltoids) or neighboring body parts (such as deltoids and traps). For maximum effect, the exercises should be diverse. So, for delts, don’t combine three overhead presses, all of which focus on the front delts. A much better choice would be a trifecta of dumbbell rear laterals (rear delts), wide-grip upright rows (middle delts), and Smith machine shoulder presses (front delts).