Phil heath side laterals

Phil Heath focuses on the crucial upper half of side lateral reps for his medial deltoids.

Sometimes halfway is the best way. Most bodybuilding training advice prescribes full ranges of motion, and generally this is the best strategy. However, if done correctly, limiting your range of motion (ROM) can focus more tension on the targeted body part. We’re not speaking here about partial reps done after reaching failure with full reps, though those too can be very effective. Our focus this month is on sets that consist of only half reps or those that start with half reps but end with full reps. This kind of “half-stepping” can make sets both harder and more effective.


The reason to do half reps is to focus more on a specific part of an exercise’s range of motion. Sometimes this is done with compound lifts to increase your strength during a sticking point. For example, powerlifters may work on only the top halves of bench presses in order to get stronger lockouts—the area where many bench presses fail. Bodybuilders can do the same thing in order to target their triceps, which are the prime movers during lockouts (pectorals play a greater role during the bottom halves of reps). Because multiple muscles are stimulated during a compound lift, it’s crucial to select the right segment of such an exercise to work the targeted area. For example, top deadlifts eliminate most lower-body movement and thus focus more on the back and traps than full deadlifts.

You can also do half reps during some isolation exercises. Select a lift with a long ROM. Shrugs, for example, would be a poor choice because their ROM is short. By contrast, leg curls have a long ROM. You also need to be aware of when the muscle is most engaged. You might assume this is always during the top halves of reps when the muscle maximally contracts, but sometimes it’s during the bottom halves when the muscle stretches. For example, the biceps are most engaged during the lower halves of preacher curls. Therefore, doing only the top halves would be inefficient.


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Leg extensions are good candidates for half reps and 21s.


Reps of varying lengths can be combined within a set. The best-known way of achieving this is via 21-curls, which consist of seven reps from the bottom to halfway, seven reps from halfway to the top, and seven full reps. Numerology aside, there’s nothing magical about either 21 or seven. You could accomplish the same with subsets of six or eight or similar amounts. Also, 21s are not exclusive to biceps routines. They work with other long-range-of-motion isolation exercises. Triceps pushdowns, leg extensions, leg curls, and pec-deck flyes are among the best candidates for 21s. Instead of doing both halves plus full reps, you can do half reps followed by whole reps or alternate half reps with whole reps. For example, do leg extensions for eight top-half reps in succession, followed, without rest, by six full reps. You can also alternate slow half reps with fast full reps throughout a set. Partial reps can feel easier after complete reps, and vice versa, breaking up the monotony of a standard set. Ideally, the halves and wholes will complement each other, allowing you to keep the muscles under tension longer than you could with only straight reps.


The key to successfully using half reps is to make certain they apply more stress on the targeted area, not less. Often, bodybuilders limit their range of motion in order to hoist more metal. Invariably, anyone doing this focuses more on the easiest portion of reps (such as the shallow top of leg presses or the bouncy bottom of incline presses) and skips the hardest segment entirely. Utilize half reps to make your sets harder and more efficient, not easier and less effective.


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  • Select compound exercises that allow you to focus on specific muscles over a limited ROM, such as triceps, during the lockouts of bench presses.
  • Select isolation exercises that have a long ROM, such as biceps curls.
  • Combining half reps with full reps in the same set allows you to better target muscles and expand your time under tension.
  • 21s can be done with many more exercises than curls, and they don’t have to total 21 reps.


  • We’ve designed an arm routine of only half reps to illustrate what can be done. Generally, only one exercise per body part should feature half reps.
  • For safety and to assure you hit the precise depth, use a power rack when doing half reps of chest presses or deadlifts.
  • To better target half reps of compound exercises, do them after isolation exercises for that muscle.
  • Slow down your half reps.


  • Pushdown 21s: 4 sets, 21* reps
  • Overhead Extension 21s: 4 sets, 21* reps
  • Bench-press Lockouts**: 4 sets, 10 reps
  • Barbell Curl 21s: 4 sets, 21* reps
  • Preacher Curl Half Reps***: 4 sets, 10 reps
  • Dumbbell Curl 21s: 4 sets, 21* reps

*7 reps from bottom to halfway, 7 reps from halfway to top, 7 full reps.

**Perform in a power rack. Go halfway down on each rep.

***Go from the bottom to halfway up.