Are Partial Reps “Cheating” or Can They Help You Gain Strength?

Are Partial Reps “Cheating” or Can They Help You Gain Strength?

(Last Updated On: April 10, 2019)

image of Cathe Friedrich doing Partial Reps Dips with a barbell on a step during Fit Split Push day.

 

Ask any fitness trainer and they’ll tell you to get the full benefits of an exercise you need to use good form and focus on the movement throughout its full range-of-motion – without cheating. When you don’t keep the muscle under tension throughout the full path of the movement, it will, as they say, keep you from getting the full benefits of the exercise – so will using sloppy form and momentum. But, as with most weight training rules, there are exceptions you can use to work your muscles differently and one of those exceptions is partial reps.

What Are Partial Reps?

Partial reps are when you intentionally limit the range-of-motion of an exercise. For example, with biceps curls, you’ve probably done a series of biceps curls called “21’s” where you concentrate on a specific range-of-motion of a bicep curl and switch that focus every seven reps. For example, during the first seven reps, you go from the bottom of the curl where your arms are extended to the midpoint where your arms are at a 90-degree angle. During the second seven reps, you focus on the range-of-motion from the halfway point to the top of the curl. Finally, for the last set of seven, you do full, range-of-motion biceps curls.

Why would you want to use the partial rep approach? It can help you break through strength plateaus. With every exercise, you have a “sticking point” and this point limits the amount of resistance you can lift. When you take the sticking point out of the picture, you can handle more weight. The sticking point limits you by acting as a barrier that keeps you from using heavier resistance. That’s where partial reps can help. With partial reps, you can start the rep beyond the sticking point, so you can use a heavier weight. Being able to use a heavier weight is an advantage if you’re trying to gain strength as it forces your muscles to recruit higher threshold motor units, ones with the greatest capacity for growth. Plus, hypertrophy of high-threshold, fast-twitch fibers enhances strength and power skills more. That’s important if you play a sport that involves strength and power.

So, partial reps have some advantages over full range-of-motion repetitions. They increase the amount of weight you can use since you’re starting the range-of-motion above your sticking point. Plus, partial range-of-motion movements using heavier weights strengthens the connective tissue that supports your muscles, making it easier for you to do full-range-of-motion reps. They help you build a foundation for lifting heavier.

But, Are Partial Reps Effective?

By now, you’re probably wondering whether partial reps as effective as full range-of-motion for building muscle strength and size. In one study, participants, performed three sets of eight triceps extensions while lying on a bench. The first group did full range-of-motion reps moving the weight from 0 to 120 degrees. A second group did partial reps, moving the weight through a range from 45 degrees to 90 degrees.

The results? Surprisingly, the group that did the partial reps experienced a greater increase in muscle cross-sectional area, 48.7% (partial) versus 28.2% (full). As an aside, the researchers also measured higher levels of blood lactate in the partial range-of-motion group and there was greater intramuscular hypoxia. So, partial reps are effective for increasing muscle size and, in this study, were superior to full range-of-motion triceps extensions where the participants did partial, mid-range reps.

What about Strength?

Gains in muscle size are one thing. With partial reps, you’re working the muscle through a limited range-of-motion and you would expect strength gains to be specific to the range-of-motion worked.  A study compared full ROM preacher curls with partial reps using the same exercise. One group did full range-of-motion preachers curls, moving the weight from 0 degrees to 130 degrees of elbow flexion. Another group did the same exercise but used partial reps, moving the resistance from 50 to 100 degrees of elbow flexion. A third group, serving as a control, did nothing. Both groups did two workouts a week for 10 weeks and used progressive overload. They encouraged the participants to do the same number of reps whether they were doing partial or full ROM curls.

The results?  Since you can handle more weight when you do partial reps, the participants who did partial ROM preachers curls used heavier weights to complete the designated number of reps and still, fatigue the muscle. In fact, the weight they used was 36% heavier than the full ROM participants. Despite this, the participants who did full range-of-motion enjoyed strength gains, on average, of 25.7%. The partial reppers only experienced a 16% increase in strength. Yet both groups experienced measurable gains in muscle cross-sectional area. The full ROM group increased muscle cross-sectional area by 9.5% and the partial ROM 7.4%. In this study, both strength and hypertrophy gains were less in the partial rep group.

This study shows why it’s important to include full range-of-motion reps in your training. Yes, you can build muscle size and strength with partial reps, but full range-of-motion reps are superior for building muscle strength and size, at least based on most studies. In fact, an analysis carried out by Strength and Conditioning Research found that full range-of-motion reps outperformed partials for strength gains in 6 out of 9 studies. You can expect some variation, depending upon the exercise but, in general, full range-of-motion leads to greater gains in muscle strength and size.

Of course, this doesn’t mean there isn’t a place for partial reps in your routine. It’s important to diversify your workouts so that you’re challenging your muscles in different ways. So, don’t shy away from partial reps or think they’re worthless. You can use a heavier resistance if you do a partial rep and start the rep beyond your sticking point. That, in turn, forces your muscles to work a little harder. In turn, you’re building a foundation for lifting heavier.

 

References:

VPS Sports. “Want Bigger Arms? Try Partial Reps”
J. Strength Cond. Res. 2012. August: 26(8): 2140-5.
J Strength Cond Res. 2004 Aug: 18(3): 518-21.
“Partial vs. Full Reps – or Both?” Bret Contreras
The Journal of Strength & Conditioning Research, 14(3), 241-247.
PhysicalLiving.com. “Are Partial Reps Better For Strength and Hypertrophy Than Full ROM?”

 

Related Articles by Cathe:

Full Reps Versus Partial Reps: Should You Do Both?

5 Advanced Strength-Training Techniques to Help You Push Past Failure

What Does Research Show about Partial Reps vs. Full Reps for Strength Training?

Resistance Training: Maximize Muscle Growth and Break Through Plateaus by Staying in the Mid-Range

 

Related Cathe Friedrich Workout DVDs:

STS Strength 90 Day Workout Program

All of Cathe’s Strength & Toning Workout DVDs
Total Body Workouts
Lower Body Workouts
Upper Body Workouts

 

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