For the past couple of years, evidence-based fitness influencers have been hyping lengthened partials, claiming you can make better gains by swerving full-ROM training and focusing exclusively on lifting at long muscle lengths.

At first glance, the claims seemed to hold water. Several studies backed the idea that training muscles in a stretched position stimulates more growth.

But there was a catch: these studies only involved beginners, and many skeptics wondered whether the results would apply to seasoned weightlifters.

This question spurred some of the biggest names in YoutTube fitness—specifically, Jeff Nippard, Dr. Pak, and Dr. Milo Wolf—to conduct a study to find out.

The researchers recruited 30 experienced “natty” weightlifters for the 8-week study.

Each lifter split their upper body training into two styles: one arm performed full-ROM exercises, while the other did lengthened partials. This way, differences between the participants’ diets, genetics, and sleep couldn’t skew the results because each person served as their own “control.” 

Throughout the study, the weightlifters also used a strict rep tempo that involved pausing for a second in the stretched position on every rep, and they took all sets to failure (the point when they couldn’t perform another rep with good form). 

The results?

Clear but underwhelming: both groups saw the same muscle gains.

Depending on your biases, you either cheered or sighed at the sight of this data. Fans of YouTube fitness felt deflated—another hyped-up strategy seemingly debunked. 

Meanwhile, skeptics felt vindicated for calling out influencers hawking lengthened-partials programs that overpromised.

I’ll skip this comment-section kerfuffle and share my takeaway instead:

Plenty of research shows that placing tension on a muscle while stretched drives muscle growth. Likewise, passive tenison—the kind generated when you lift a weight—is also paramount for hypertrophy. 

(That’s why squats—which stretch the glutes—and hip thrusts—which don’t—build your butt equally well.)

The results from this study suggest that full-ROM training delivers the benefits of lengthened partials, especially when you “sit” in the stretch for a beat on each rep. In other words, provided you train through a full ROM using a controlled cadence, you’ll get all the muscle-building benefits on offer.

Plus, training like this comes with an extra perk: you also strengthen your muscles through their full range of motion—at short and long lengths—which is key for well-rounded strength.

Win-win.

That’s why full-ROM training is the style I use, advocate in my books for men and women, and recommend to clients on my body transformation coaching program—and there’s plenty of proof it works.

Physique Transformations