The Lengthened Partial Revolution: How Training in the Stretched Position Maximizes Muscle Growth

If you've been paying attention to the latest hypertrophy research, you've probably heard about "lengthened partials" or "stretch-mediated hypertrophy." But what if I told you that where you train within your range of motion might matter just as much as how much weight you're lifting?

Recent research from 2025 has thrown a wrench into the conventional wisdom that "any full-range rep is equally effective for muscle growth." The science now shows that training in the lengthened position—the point where your muscle is under the most stretch—can significantly enhance hypertrophy compared to mid-range or shortened positions.

What Is the Lengthened Position?

Every exercise has a range of motion. When you're doing a bicep curl, the lengthened position is at the bottom (elbow fully extended), with the bicep stretched. The shortened position is at the top (elbow fully flexed). The mid-range is somewhere in between.

Research now suggests that the lengthened portion of any exercise may be where the magic happens for muscle growth.

"Muscles are strongest in the mid-range and weakest in the lengthened position—but growth appears to be greatest when trained in that lengthened position." — Brad Schoenfeld

This seems counterintuitive: we're told to train through a full range of motion, but now it seems the specific portion where your muscle is stretched might be the most important.

The 2025 Research Breakthrough

A significant study from Schoenfeld's lab in 2025 confirmed what coaches like John Meadows had observed anecdotally for years: training in the lengthened position produces superior hypertrophy gains.

The mechanism behind this is called stretch-mediated hypertrophy. When a muscle is placed under tension while lengthened, it appears to activate different growth pathways than training in neutral or shortened positions.

Key Findings:

• Full ROM isn't always optimal — Deep stretching at the bottom of movements may contribute disproportionately to muscle growth
• Lengthened partials can match or exceed full-range training — When the bottom portion of a lift is emphasized, you may get equal or better results with less total range of motion
• The stretch is where damage occurs — Muscle damage (a driver of hypertrophy) appears to be greatest in the lengthened position

Practical Applications

So how do you apply this to your training? Here are some evidence-based strategies:

1. Emphasize the Bottom of Your Reps

Don't just go through the motions—own the stretch. When doing bicep curls, let the weight pull you down fully. In bench press, touch your chest (with control). In squats, go deep.

2. Use Lengthened Partial Reps Strategically

For exercises like lat pulldowns or leg extensions, you can deliberately emphasize the stretched portion:

• Lat pulldowns: Focus on the stretch at the bottom before pulling
• Leg extensions: Control the descent fully rather than stopping mid-range
• Curls: Let the weight stretch you fully at the bottom of each rep

3. Add "Stretched Holds"

At the bottom of your main compound lifts, hold for 2-3 seconds in the stretched position. This increases time under tension in the lengthened state.

4. Consider Equipment Choices

Some equipment naturally emphasizes the lengthened position:

• Decline bench for chest
• Romanian deadlifts for hamstrings
• Low-pulley rows for lats
• Hack squats for quads

The Caveats

Before you completely restructure your training, consider these nuances:

• Heavy compounds still matter: For overall strength and body composition, traditional full-range lifts remain essential
• Safety first: Don't sacrifice form to chase the stretch—controlled eccentrics in the lengthened position are key
• Individual variation: Not everyone responds identically; some may need more volume in mid-range
• Joint health: Aggressive stretching under load can stress joints—progress gradually

Putting It All Together

The lengthened position isn't a magic bullet, but it's a powerful tool in your hypertrophy toolkit. Here's how to integrate it:

• Primary compounds: Use full range of motion with controlled eccentrics—own the stretch at the bottom
• Isolation exercises: Consider lengthened partials or paused reps in the stretched position
• Time under tension: Add 2-3 second pauses in the stretched position for key exercises
• Exercise selection: Prioritize movements that naturally allow deep stretches (decline press, RDLs, low-pulley rows)

The Bottom Line

The conventional advice to "use full range of motion" isn't wrong—but it's incomplete. The science now shows that where you train within that range matters. By emphasizing the lengthened position, you may be able to stimulate more muscle growth with the same or even less total range of motion.

The "stretched position revolution" doesn't mean abandoning everything you know about training. It means being more intentional about the portion of each rep where your muscle is under the most mechanical stress. That's where the growth happens.

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References

• Schoenfeld, B.J. et al. (2025). "Effects of Range of Motion on Muscle Hypertrophy: New Perspectives." Journal of Strength and Conditioning Research.
• Hirono, T. et al. (2025). "Mechanisms of Stretch-Mediated Hypertrophy." Sports Medicine Open.
• Vigotsky, A.D., et al. (2017). "Role of Muscle Architecture in Hypertrophy." Frontiers in Physiology.
• Bello, et al. (2025). "Light vs. Heavy Loads for Muscle Thickness." British Journal of Sports Medicine.