Regardless of your goal—putting on size or strength, this technique is worth giving a shot.
The 50-rep technique is simple to understand, but hard to do! It's nothing more than doing an exercise to a total of 50 reps. Now, all 50 reps do not have to be done all in one set—you can do it in 2, 3, even 5 sets. Whatever it takes to get to 50, just do it.
Specifics
Choose a moderate or light weight that you can lift for at least 12-15 reps on the first set. If you fall short, drop the weight and continue your set. On the next set, increase the weight or keep it the same and perform as many reps as you can and do the same for the next set. Keep doing it in this way until you reach 50 reps.
Now, when my training partner introduced this technique to me, especially on the squats, I felt a burn like I never felt before! It definitely made my squat stronger and it got my quads more cut than usual. I liked it a lot, and I know lots of hardcore lifters would too.
Tips
To really utilize this method, try doing it after a mass exercise like the bench>, squat, barbell curls, triceps extensions, etc.
Do only one exercise using this method—you won't have it in you to do another set! The good exercises to use it on would be cable cross-overs, push-downs, rows, pull-downs, pull-ups, preacher curls, leg extensions, leg press, or any other shaping exercise.
Taking It Up A Notch
Now, the 50-rep method can be used in conjunction with a drop set. After one heavy set of say, calf raises, drop the weight and start to do 50-reps.
What Is A Drop Set? A drop set is a set where you do as many reps as you can with a certain weight, then immediately lower the weight and do more reps. There should be as little rest as possible between sets.
If you stop at around 20, drop the weight and continue. Then you stop at 35, drop again and do more. Then when you reach 45, drop again and do 5 more until you reach 50. This should give any muscle, especially the calves, a huge shock that you will definitely feel in the morning.
But if you're going to use the 50-rep/drop-set combo, either do it after your mass-building exercise like standing calf raises, or do it as your only exercise for that body part.
Other than that, you can use this method on machine equipment if you don't have a partner. You can use it with free weights if you have a partner. Remember, pick a weight that you can use for more than 12 reps. After that, increase or keep the weight the same and continue until you do 50-reps. Also, do as many sets as it take to get 50-rep total.
Good luck, and feel the burn!