If you haven’t tried, or even heard of the “21s” method of working out, let me explain it. Every exercise has 3 different ranges of motion (ROM). The “bottom” portion, which is from the resting or starting position to about the halfway point; the “top” portion, which is from halfway to the position where the rep is complete; and the full ROM, from bottom to top. To make this more clear, we’ll use the bench press. The bottom portion is the bar touching your chest, to halfway to lockout. The top portion is from halfway to lockout to the bar fully up, arms locked out. The full ROM is a complete rep.
Taking advantage of these different portions of a rep can greatly change the intenstiy of a workout and spur on strength and hypertrophy gains. The 21s method isn’t new. It’s considered a classic technique, mastered in the golden age of bodybuilding. But even then it was, primarily, used with biceps curls. No reason to stop there; 21s can be utilized for every muscle group.
The strength and hypertrophy gains that are produced by 21s come from very simple processes. When utilizing a 21s system, the time under tension (TUT) is significantly higher than sets of standard reps. Meaning that the targeted muscle group is working for a longer period of time. I’ve written about it before, but TUT is a very important variable to manipulate when working out to increase the intensity of a workout. Another reason 21s are so beneficial is the length-tension curve, or length-tension relationship. The length-tension curve is the curve of the potential for a muscle to generate force as it goes through an eccentric or concentric ROM. In simpler terms, muscles are weaker at the top and bottom portions of a given exercise. The midrange of a ROM is where the muscle produces the most tension, leading to the most strength and hypertrophy gains.
A 21s workout will go something like this: 7 reps using the bottom ROM, 7 reps using the top ROM, and 7 reps with the full ROM. These 21 reps (hence the name) are considered 1 set. Due to the high volume of reps, the ideal weight range is 50-60 percent of your 1 rep max. A fun and challenging tweak to the 21s system is to include 7 second isometric holds in the midrange of a ROM, where tension on the muscle is the highest.