It seems intuitive that using full reps as opposed to partial ones would lead to greater strength gains. After all, the goal of training is to work a muscle through its entire range of motion. Still, a number of fitness trainers encourage trainees to do partial reps for at least a portion of the total reps they do. Oftentimes, “partials” are added at the end of a set when fatigue is setting in and doing a full rep might be too challenging. Some bodybuilders also use partial reps to work on a weakness or “sticking point” in a lift.
Are there real benefits to doing partial reps or is it better just to stick with full reps? If you’ve ever wondered what role range-of-motion plays in building strength and whether partial reps offer additional benefits, read on.
What Does Research Say about Partial vs. Full Reps?
A number of studies over the years have looked at how range-of-motion impacts strength gains. Strength and Conditioning Research presented the results of these studies. Six of the nine studies showed full range-of-motion reps were superior to partials for strength gains, while three studies showed no difference in strength gains between the two types of reps. The participants in these studies were untrained or were lightly trained and no advanced trainees took part in these studies.
For the most part, these studies showed partial reps enhanced partial range-of-motion strength, but weren’t as effective for boosting full range-of-motion strength. Full range-of-motion reps also appear to be superior for building dynamic strength and power. Based on this, if you’re trying to build strength in a muscle group throughout its entire range-of-motion, full reps are more effective than partials.
This doesn’t mean you can’t build strength using partial reps, but some of the strength gains apply only to the partial range-of-motion that you used to work the muscle. In other words, if you work a muscle over 50% to 75% range of motion you’ll gain the most strength at that level. One study even showed full range-of-motion reps using light weights were superior to partial reps using heavier weights for building strength.
Partial Reps and Muscle Growth
What about muscle hypertrophy? A study published in Strength and Conditioning Research in 2012 found both full and partial reps increased muscle thickness in elbow flexors, however full reps lead to a greater increase in muscle thickness than partial reps. What about upper body versus lower body? Greater gains with full reps apply to both lower and upper body exercises. Full range-of-motion biceps curls showed more significant increases in muscle size than partial curls, while full range-of-motion squats and leg extension were superior to partial squats.
Is There a Role for Partial Reps?
According to the current evidence, most of your training should focus on full reps using good form for strength gains. That doesn’t mean there isn’t a role for partial reps. In one study, trained participants did three sets of partial squats and three sets of full squats. Another group performed six sets of full squats and no partial squats. Although the group who did some partial reps developed more strength and power, the difference was only borderline significant.
Where partial reps will have the most benefits is when you’re trying to correct a weak portion of a movement. For example, when you’re doing overhead presses and you have problems moving the weight through a “sticking point,” you can use partial reps to build more strength at that level. Strengthening the area of weakness will improve your performance when you do full range-of-motion reps. Plus, when you execute partial reps through the mid-range of motion, you’re not relaxing the muscle at the top or bottom of the movement, so you’re keeping the muscle under constant tension. Because it takes less time to do a partial rep, the muscle stays under tension for a lesser amount of time. You can compensate for this by doing more reps when you do partials.
Also, once you’ve built up baseline strength with full-rep training you can use partial reps at the end of a set when your muscles are too fatigued to do full reps as a way to maximize muscle fatigue. Doing this enables you to eke out a few additional partial reps that you normally wouldn’t be able to accomplish.
For some exercises, partial reps increase the tension you place on the muscle. For example, when you do a set of biceps curls, the tension is minimal at the bottom of the exercise when your arms are straight and at the top of the movement. If you eliminate the points of minimal tension by doing a partial rep through the midrange of the movement only, your biceps muscle is under constant tension with each partial rep.
You’re probably familiar with “21s,” a set of three biceps exercises that involve 2 sets of partial biceps curls from bottom to midpoint and from midpoint to top (7 reps each) followed by 7 full reps. This is a good way to work your biceps at all levels and maximize fatigue.
Partial reps also stimulate a greater anabolic response because you’re holding the muscle under tension throughout the movement, leading to a greater build-up of lactic acid. There’s no “lockout” period. Finally, if you’ve always done full reps, your muscles have adapted to full range-of-motion movements to some degree. Adding a few partial reps into your workout gives your muscle a new stimulus for growth.
The Bottom Line
You’ll get more “bang” for your strength training buck if you stick mainly with full range-of-motion reps, using progressive overload, but you can still use partial reps to correct point of weakness. You can also employ them at the end of a set of full reps to maximize muscle fatigue and diversify your workout. If you’re just starting out, stick with full reps for at least 6 months before adding partial reps.
Strength and Conditioning Research. “How Does Range-of-Motion Affects Strength Gains”
J. Strength Cond. Res. 2012. August: 26(8): 2140-5.
“Partial vs. Full Reps – or Both?” Bret Contreras
J Strength Cond Res. 2004 Aug: 18(3): 518-21.
The Journal of Strength & Conditioning Research, 14(3), 241-247.
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