Opinion: Long-Length Partial Reps Are Overrated for Bodybuilding

At my gym, (and probably at yours, too) there’s an older gentleman who spends his workouts idling on various machines, performing quarter-range-of-motion everything before heading home. Good on him for staying active. I would have scoffed at his “suboptimal” technique in years past. 

But in 2024, this individual is an evidence-based, scientifically optimized muscle-building Gigachad. Long-length partials — let’s call them LLPs — are the hottest thing in bodybuilding since Chris Bumstead.

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But just like the feeling that washes over me on the rare occasion my phone lights up with a notification saying I finally got a new match on Hinge, if something sounds too good to be true, it probably is. The dialogue around LLPs is too good to be true. I’m going to go ahead and hollow out the hype: long-length partial reps are overrated.

What Are Long-Length Partials?

LLPs are regarded as the next big thing in muscle-building science, thanks to a growing body of research and a robust press tour from creators and academics like Milo Wolf. Dr. Wolf is a researcher whose doctoral thesis (1) concerned the hypertrophy and strength effects of training your muscles in stretched (or lengthened) positions. 

Speaking to Dr. Mike Israetel, Wolf defined LLPs as: “…partial reps [of resistance training exercises] performed at longer average muscle lengths.” In more practical terms, Wolf urges you to imagine the bottom half of a biceps curl. 

When your elbow is fully bent, your biceps are contracted and shortened. As you open your arm, your biceps stretch out against the weight of whatever you’re holding. That’s where the magic happens. Simple enough. 

https://www.youtube.com/watch?v=c90y7RQo_lQ

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You can find Wolf all over fitness podcasts singing the praises of LLPs, while thought leaders like Dr. Israetel and Jeff Nippard have pounced on the concept because it’s new. And shiny. And converts nicely into clickable content (BarBend isn’t innocent here either). And, in fairness, the (2) evidence (3) does (4) exist. (5)

Exercise science literature usually plays things pretty close to the chest — lots of “compelling but inconclusive” or “we think this works for some people sometimes, but only under these specific conditions.” Academia may be endorsing LLPs with more zest than usual, but that doesn’t mean we should all stop locking out our knees and elbows during our bodybuilding workouts or only perform bottom-half reps.

Why They’re Overrated

I get why Wolf & Co. are so excited. Sports science isn’t exactly an emerging field of study; the bulk of what works for muscle-building was discovered years back, and while there’s nuance to how to build muscle, it’s mostly settled law. Anyone who says otherwise probably wants to sell you something.

LLPs are very promising, but you’re wise to be wary of any individual or group that will bat a little too hard for any idea. The current discourse surrounding lengthened-partial training tends to ignore some of its limitations: 

1. They may not work for every muscle.
2. The magnitude of change is small.
3. Peak muscle contractions are important for bodybuilders.
4. Full range of motion training has unique benefits. 

I don’t want to give the impression that Drs. Wolf & Israetel, or any other prominent evidence-based voice in the bodybuilding space, might be turning a blind eye to the limitations of LLPs.

To their credit, these guys habitually argue against themselves in the spirit of intellectual honesty, or are candid about where lengthened-partial training falls short. Swords sheathed? Good, let’s dig in.

They May Not Work for Every Muscle

Plenty of studies sing the praises of LLPs, but other research has presented conflicting findings, particularly regarding how individual muscles or muscle groups respond to the technique.

• In 2020, Nunes et al. investigated the effects of long vs. short-length training with the preacher curl. In the abstract, they say, “hypertrophy was similar…whether torque emphasis was carried out in the final or initial degrees of the range of motion.” (6)
• Stasinaski & colleagues carried out a similar study on the triceps muscle in 2018: “These results indicate that muscle strength and architecture of elbow extensors adapt similarly…at either long or short fascicle length.” (7)

It’s premature to declare that LLPs work wonders for all of your muscles, all of the time. In fairness, lengthened partials (or long-duration loaded stretches) might work exceptionally well for the calf muscles. (3)(8) There appears to be variability in both directions.

The Amount of “Extra” Growth Is Small

Remarking on the magnitude of most existing LLP studies, Wolf credits the technique with increasing hypertrophy outcomes by about 3 to 8% compared to using a full range of motion (ROM). In the context of a single study or if you’re a rank beginner, an eight-percent increase can be pretty spectacular. In the real world, it might not be worth your time.

This isn’t to say that any proponent of lengthened partials deliberately obfuscates their merit. No sane person, whether they have a microphone at their lips or not, would suggest that utilizing LLPs will turn you into the next Mr. Olympia. 

The World’s Smartest Muscle Building Technique (https://www.youtube.com/watch?v=ftpH4-xFGQI)

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It’s just something to keep in mind — the technique does appear to move the needle, but banging out some lengthened partials won’t supercharge your muscle-building endeavors, especially if you’ve got a half-baked training plan, recover like crap, or don’t eat properly in the first place. 

Peak Contractions Are Important for Bodybuilders

Shortened partials or emphasizing the “peak contraction”, as Dr. Israetel regards it, may be physiologically subpar for hypertrophy, but doing so is still valuable for any competitively-inclined bodybuilder. 

One common bodybuilding cue during the lat pulldown is to pretend to perform a back-double-biceps pose as you execute each rep. If you only do the first half of the range of motion, you skip opportunities to practice and demonstrate muscular control.

Do you need to fully contract your pecs during machine chest flyes to know how to perform the “most-muscular” pose? Of course not. But you can’t tell me with a straight face that squeezing your pecs together on chest day — along with the pump it provides — isn’t one of the best feelings in bodybuilding.

Should you bin LLPs altogether just to savor the ecstasy of a pumped-up posing session? Hard telling, but probably not. It’s just something to consider.

Full Range of Motion Training Has Other Benefits

Bodybuilding is about growing as much muscle as possible. But most of us don’t train under the supervision of professional coaches or in a laboratory setting where it’s reasonable to analyze or pursue one adaptation while ignoring others.

In simpler terms, even if you’re a bodybuilder, you’re still lifting weights, and full-ROM resistance training provides all sorts of tangential benefits that inadvertently help you put on mass. Studies tend to show that strength gain is specific to range of motion; if you only perform the bottom half of a bench press, your lockout strength will undoubtedly suffer come max-out day. (2)(9)(10) 

https://www.youtube.com/watch?v=griLcprPfvY

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Furthermore, deliberately omitting a portion of your ROM probably isn’t conducive to joint integrity and postural control. Who wants to lose confidence in their ability to hold something heavy overhead because it’s a single-digit percentage “better” to only do the first half of the shoulder press? 

Never mind that arbitrarily cutting your range of motion short (or long, in this case) makes it more difficult to track progress. When you train with a full ROM, the “start” and “end” of each repetition are clearly defined; on the bench, touch your chest and then lock your elbows. This makes it easy to standardize and measure your strength.

A Measured Approach

Long-length partials are quite compelling on paper. In practice, diving headfirst into a training technique that endorses not mastering a full range of motion isn’t wise. If your favorite content creators want you to implement LLPs throughout your bodybuilding program, go for it. You might eke out a bit of extra muscle.

But take a measured, practical approach — bottom-halving your bench presses may be scientifically optimal or whatever, but from the outside, it kind of looks like a new flavor of ego-lifting. If you ever want to compete in a powerlifting meet, you’ll have a lot of ground to make up. 

Remember: Science is meant to inform, discover, guide, and rationalize. It’s not religious dogma. Hell, Tommy Lee Jones said it best almost three decades ago in Men In Black:

“Fifteen hundred years ago, everybody knew the Earth was the center of the universe. Five hundred years ago, everybody knew the Earth was flat.

Imagine what you’ll know tomorrow.” 

References

1. Wolf, M., Androulakis-Korakakis, P., Fisher, J., Schoenfeld, B., & Steele, J. (2023). Partial Vs Full Range of Motion Resistance Training: A Systematic Review and Meta-Analysis. International Journal of Strength and Conditioning, 3(1). 
2. Pedrosa, G. F., Lima, F. V., Schoenfeld, B. J., Lacerda, L. T., Simões, M. G., Pereira, M. R., Diniz, R. C. R., & Chagas, M. H. (2022). Partial range of motion training elicits favorable improvements in muscular adaptations when carried out at long muscle lengths. European journal of sport science, 22(8), 1250–1260. 
3. Kassiano, W., Costa, B., Kunevaliki, G., Soares, D., Zacarias, G., Manske, I., Takaki, Y., Ruggiero, M. F., Stavinski, N., Francsuel, J., Tricoli, I., Carneiro, M. A. S., & Cyrino, E. S. (2023). Greater Gastrocnemius Muscle Hypertrophy After Partial Range of Motion Training Performed at Long Muscle Lengths. Journal of strength and conditioning research, 37(9), 1746–1753. 
4. Pedrosa, G. F., Simões, M. G., Figueiredo, M. O. C., Lacerda, L. T., Schoenfeld, B. J., Lima, F. V., Chagas, M. H., & Diniz, R. C. R. (2023). Training in the Initial Range of Motion Promotes Greater Muscle Adaptations Than at Final in the Arm Curl. Sports (Basel, Switzerland), 11(2), 39.
5. Maeo, S., Huang, M., Wu, Y., Sakurai, H., Kusagawa, Y., Sugiyama, T., Kanehisa, H., & Isaka, T. (2021). Greater Hamstrings Muscle Hypertrophy but Similar Damage Protection after Training at Long versus Short Muscle Lengths. Medicine and science in sports and exercise, 53(4), 825–837. 
6. Nunes, J. P., Jacinto, J. L., Ribeiro, A. S., Mayhew, J. L., Nakamura, M., Capel, D. M. G., Santos, L. R., Santos, L., Cyrino, E. S., & Aguiar, A. F. (2020). Placing Greater Torque at Shorter or Longer Muscle Lengths? Effects of Cable vs. Barbell Preacher Curl Training on Muscular Strength and Hypertrophy in Young Adults. International journal of environmental research and public health, 17(16), 5859. 
7. Stasinaki, A.-N.; Zaras, N.; Methenitis, S.; Tsitkanou, S.; Krase, A.; Kavvoura, A.; Terzis, G. Triceps Brachii Muscle Strength and Architectural Adaptations with Resistance Training Exercises at Short or Long Fascicle Length. J. Funct. Morphol. Kinesiol. 2018, 3, 28. 
8. Warneke, K., Brinkmann, A., Hillebrecht, M., & Schiemann, S. (2022). Influence of Long-Lasting Static Stretching on Maximal Strength, Muscle Thickness and Flexibility. Frontiers in physiology, 13, 878955. 
9. Graves, J. E., Pollock, M. L., Jones, A. E., Colvin, A. B., & Leggett, S. H. (1989). Specificity of limited range of motion variable resistance training. Medicine and science in sports and exercise, 21(1), 84–89. 
10. Bazyler, C. D., Sato, K., Wassinger, C. A., Lamont, H. S., & Stone, M. H. (2014). The efficacy of incorporating partial squats in maximal strength training. Journal of strength and conditioning research, 28(11), 3024–3032. 

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