Weider Principle #22: Partial Reps

Limit your range of motion to maximize muscle overload


There is no Weider Full Range of Motion Principle. I just made it up. Perhaps the fact that you should strive for complete reps that go from an all-out stretch to a thorough contraction was simply too obvious for Joe Weider to codify in a tenet. It has long been an exercise fundamental— and we’re about to break it. You don’t have to go all the way. Sometimes an exercise is made more effective by using only part of its range of motion. The Weider Partial Reps Principle increases tension by decreasing movement.

This is one

of the most confusing training tenets. That’s because when bodybuilders refer to “partial reps” (or just “partials”) they’re often speaking of reps done for a shorter range of motion after reaching failure with full reps. In contrast, the partials of the Weider Partial Reps Principle are done from the first rep to the last, and there are no full reps in that set. For our purposes, partials done only to extend a set beyond full-rep failure are called “burns.” They have their own Weider principle, and we’ll focus on it in the next installment of H.U.G.E.® to further clarify the diferences.

Partial reps are not compatible with every exercise. Some lifts (like power cleans) are too ballistic, some (like shrugs) have too short a range of motion, and some (like squats) have less bodybuilding benefit when done with more weight for a brief movement. On the other hand, for bodybuilders, partial deadlifts are arguably superior to full deadlifts because, by doing rack deads that focus only on the top half of the movement, lower-body stimulation is limited and thus a greater focus is placed on back and traps. But it’s not just compound lifts that can benefit from partials. Isolation exercises with strong contraction points are also good candidates. Lifts like side laterals, barbell curls, and leg extensions can be made more intense by lowering each rep only halfway and thus placing a greater emphasis on contractions.


Here are the pluses of using partial reps.


    By focusing on only a portion of a rep, you can remove the part(s) of a rep when tension is lessened. For example, when you do full biceps curls, biceps tension is lost at the start of reps when your arms are straight. If you do only the top half of curls, your bi’s never rest.

  • FOCUS COMPOUND EXERCISES: By working only part of a compound exercise, you can target one body part instead of multiple body parts. For example, if you do bench presses in a power rack set up so the bar travels down only a few inches on each rep, you’ll work the triceps more than usual (and the pecs and front delts less) because your tri’s do most of the work when locking out bench presses.


There are two potential pitfalls to utilizing partial reps.


    It can be difcult to hit the correct depth each half rep. For example, if you do top deadlifs without a powerrack you’ll probably spend too much effort trying to stop the descents of reps, losing your focus and potentially wrenching your back. Use a power rack. On exercises that don’t work with a power rack, a spotter can help you maintain rep depth and the correct groove.

  • REDUCED RANGE OF MOTION: Partial reps can be a growth disadvantage if you rely on them too much. Generally, “going all the way” is better than “half measures.” Use partials as an occasional technique to focus the tension of one or two exercises per body part, but you should maintain a full range of motion on the other exercises for that body part.


Partial reps and full reps can be combined in the same set. The classic way to do this is the 21-curl—a set of biceps curls that starts with seven reps of bottom-half curls, then goes to seven reps of top-half curls, and ends with seven full reps. Numerology aside, there’s nothing magical about 21. You can do a variety of half-rep and full-rep combinations, and you can do these with various exercises. Leg extensions and leg curls are two good candidates for “21s” or “18s” or whatever number you hit. The important thing is to start with half reps and end with full reps. FLEX