Multi Exercise sets are an exceptional variation method because they hit the muscles from every angle in one workout. They're simple: instead of doing 3 or 4 sets of 2 or 3 different exercises for a workout, you do 1 sets of, well, however many exercises you choose to do, which is typically 6-12. So for example, you go into the gym to train chest. First, you hop on the bench and do a few warm-up sets. When you're ready to get to work, you bang out a set. Then grab the dumbbells and do some presses with those. Right after that, grab some lighter dumbbells and use them for flyes. Next, raise the bench up and do the same barbell, dumbbell, flye pattern on the incline. After those 3 sets are done, finish off with some declines, or maybe even some cable crossovers. Now when I say this I don't mean continuously, like supersets. Just do them as you would do any other workout, include the break, you're just going to be jumping from exercise to exercise. And remember, you still have to warm up first, especially since you are going to come at the given bodypart from so many unexpected angles.
Since I did bring it up though, in order to increase the intensity even more, you can add supersets, tri-sets, and drop sets to these. In addition to the ones I just mentioned, you can add virtually any other practical shock methods, it's just that the ones I mentioned happen to be the best. Of course, supersets and the others will drain you very fast so be warned. For example, you could superset bench presses with flys. After doing one superset of those you could move on to a superset of flat dumbbell presses and cable crossovers. Next, move on to some incline dumbbell presses and incline flyes. Finally, finish off with the Pec Deck and declines. Of course, you don't have to superset the whole workout as I outlined here. If you wanted to superset just 2 movements then continue on with regular ol' rest interval training, go ahead- it's up to you to experiment and find out what gives you the best results.
On the other hand, there is one huge downside to Multi-Exercise Sets. If you go to a gym, unless it's empty most of the time, you will have a lot of trouble jumping from place to place, especially if you're doing supersets (tri-sets and giant sets are probably out of the question). It seems like it's impossible to do supersets in a gym, it's as if people don't understand the concept of them. I quickly try and explain what I'm doing, but they never cease to amaze me with their…ugh nevermind. Anyway, the best place to do some Multi's is at a home gym. If you happen to have the luxury of possessing your own equipment, or know someone that does, then take advantage of the situation you're in because you're better off. If you're doing supersets though, just make sure that you remember to get everything ready before you start the workout: bars loaded up, bench inclined…you know what I mean. Otherwise you'll be rushing to do it in between sets and kill the no-rest concept. I workout at home, and I must say I love it. Just me, sometimes my cousin (partner), and the weights…and of course I have that dinner table on the other side of the room (I had to beg for every bit of space I have for that weight area…long story).
With Multi's, the combinations are endless. If you're a firm believer in doing lots of flat bench presses, then you could have done 3 sets of those and cut out the dumbbell presses. Or, if you have a weak upper-chest, you could have started on the incline and/or done more total sets on the incline. All I'm doing is showing you the idea of what to do. It's up to you to get creative and mix it up.