Lengthened Partials: The Half-Rep Technique That Might Actually Work

Let's talk about something that sounds completely counterintuitive: doing half-reps on purpose. Sounds like crazy talk, but it might just be a crazy as a fox.

I know, I know. Your gym teacher, your high school coach, and that guy at the gym with the tribal tattoos all told you that half-reps are cheating. And they're right... mostly. But what if I told you there's a specific type of partial rep that might actually be better for building muscle than full range of motion?

Welcome to the world of lengthened partials where everything you learned about "full ROM or you're wasting your time" gets a little bit complicated.

What Are Lengthened Partials?

Lengthened partials (sometimes called "long length partials" if you want to sound smart at parties no one invited you to) means doing only the first portion of a lift's range of motion – specifically, the part where your muscles are at their longest.

In practice, this looks like:

• Squats: Going deep but only coming up halfway (not the bro-science quarter squats where you load up 500lbs and bend your knees slightly)

• Bench press: Touching the bar to your chest but only pressing halfway up

• Curls: Starting from full arm extension but only curling to 90 degrees

• Calf raises: Going into a deep stretch but only coming up partway

Basically, you're doing the hard part and skipping the easy part. Which, admittedly, is the opposite of what most people do in the gym.

Why Would Anyone Do This?

Here's where the science gets interesting. Over the past decade, researchers have consistently found that training muscles at longer lengths produces more hypertrophy than training at shorter lengths. This has been shown through:

Different exercises for the same muscle: Seated leg curls (where your hamstrings are more stretched due to hip position) produce more hamstring growth than lying leg curls, even though both work through the same knee range of motion.

Partials at different lengths: When researchers compare partials head-to-head with the same degrees of motion, initial range partials (lengthened) beat end range partials (shortened) for muscle growth.

Isometric work: Holding contractions at longer muscle lengths produces more growth than holding at shorter lengths.

Exercise variations: Overhead triceps extensions (which stretch the long head of the triceps due to shoulder position) produce more triceps growth than pushdowns, even when elbow range of motion is matched.

So the hypothesis is pretty straightforward: if longer muscle lengths are where the magic happens, why waste energy grinding through the shortened portion of the lift? Just spend all your time in the lengthened zone and profit.

The Evidence (Spoiler: It's Nuanced)

Some studies have found lengthened partials to be absolutely crushing it:

• Kassiano et al. found that lengthened partial calf raises produced more than double the muscle growth of full range calf raises (15.2% vs 6.7% in the medial gastrocnemius). That's not a typo – double.

• Pedrosa et al. showed that lengthened partial leg extensions resulted in similar overall quad growth but more growth in the distal (lower) regions compared to full range training.

• A study on calf training found that just adding some lengthened partials after hitting failure on full ROM sets produced more growth than stopping at full ROM failure.

But then other studies show... not much difference:

• Wolf et al. found similar biceps and triceps growth whether trained lifters used lengthened partials or full ROM

• Several recent studies on various muscle groups showing basically equivalent results

So what gives? Research and the human body are complicated.

The Missing Piece: Tension at Length

Here's the detail that makes everything click: it's not just about reaching a long muscle length it's about producing high tension when the muscle is long.

Let me explain with an example that'll make sense. Consider two biceps exercises:

Incline curls (arms behind your body while seating in an inclined bench): The biceps are super stretched at the bottom due to shoulder position. Great for the biceps brachii.

Preacher curls (arms in front): Not as much stretch on the biceps brachii, but guess what? Because of the arm position relative to gravity, you hit maximum tension when your forearm is parallel to the ground which happens to be when your brachialis (the other elbow flexor) is at a longer length. Result: preacher curls grow the brachialis more.

The lesson: the exercise needs to be challenging when your muscle is long, not just allow you to reach a long length.

When Lengthened Partials Actually Make Sense

Based on the research and logic, here's when lengthened partials are most likely to be worth your time:

Good Candidates:

1. Calf raises – These are hardest at lockout (shortened position). The stretched position is actually the easy part. By doing lengthened partials, you're spending more time and energy in the stretched position without exhausting yourself fighting through lockouts. The evidence here is particularly strong.

2. Machine exercises that are hardest at lockout – Many leg press, leg curl, and leg extension machines have resistance profiles that make them disproportionately challenging when the muscle is short. Lengthened partials on these make logical sense.

3. Cable exercises – Cables provide constant tension, so you can manipulate where the exercise is hardest. For example, cross-body cable lateral raises keep tension on the delts at longer lengths compared to dumbbell raises.

Poor Candidates:

1. Squats and deadlifts – These are already hardest when your muscles are longest (out of the hole, off the floor). Lengthened partials would be redundant. Plus, staying in the deep position without locking out makes breathing harder, which actually limits how many quality reps you can do in that lengthened position.

2. Most pressing movements – Bench press, overhead press, dips these are typically hardest in the stretched position already. The lockout is basically a rest period for your muscles.

3. Romanian deadlifts – Already emphasizing the stretched position of the hamstrings. Making them lengthened partials would just be called "not finishing your reps."

How to Actually Implement This

If you want to experiment with lengthened partials (and you should, because experimentation is what separates lifters who make progress from lifters who do the same thing for 10 years), here's my recommendation:

Start small: Pick 1-2 exercises per muscle group. Don't overhaul your entire program.

Prioritize safety: Use machines, cables, or exercises where you won't get pinned. A lengthened partial leg press? Smart. A lengthened partial back squat where you get stuck in the hole? Less smart. Your physical therapist will not be impressed.

Try it where the evidence is strongest: Calf raises are the obvious starting point. The evidence here is really compelling, and they're incredibly safe to take to failure.

Use mechanical stops if possible: Many machines let you set safety pins or stops at specific ranges. Use them. This lets you confidently train to failure without worrying about getting crushed.

Combine with full ROM work: You don't have to choose one or the other. You can do full ROM until failure, then bang out some lengthened partials. Or do some movements with full ROM and others with lengthened partials. Personally, I often do the former.

Expect more soreness initially: Training with more emphasis on the stretched position tends to cause more muscle damage initially (DOMS). Your first few sessions might leave you walking like a newborn giraffe. This will improve.

The Practical Reality Check

Here's the thing nobody wants to admit: even if lengthened partials do provide an advantage, it's probably a small one. We're not talking about doubling your gains (despite that one impressive calf study). We're talking about potentially optimizing things by maybe 2-10% at best.

For most people, most of the time, the bigger priorities are:

• Training consistently

• Pushing close to failure (it is all about effort)

• Eating enough protein

• Getting enough sleep

• Progressive overload over time

Lengthened partials are a tool in the toolbox, not a magic bullet. They're for people who already have the basics dialed in and are looking for that extra edge.

The Broader Principle

Really, the whole lengthened partial conversation is part of a bigger, more important principle: training with an emphasis on longer muscle lengths is beneficial for muscle growth.

You can achieve this through:

• Lengthened partials (one option)

• Choosing exercises that load muscles at long lengths (overhead triceps extensions, Romanian deadlifts, deep squats)

• Pausing in the stretched position

• Training to failure (your last attempted rep is basically a lengthened partial)

• Full ROM on exercises that are already hard in the stretched position

Lengthened partials are just one way to apply this principle. They're not the only way, and in many cases, they're not even the best way.

Why Do Studies Keep Contradicting Each Other?

Quick sidebar because this confuses everyone: you'll notice that every few months, a new study comes out that seems to completely contradict the previous one on lengthened partials. This isn't because science is broken or researchers don't know what they're doing.

It's because we're looking for small effects in small samples. Welcome to exercise science! When you're trying to detect a difference that might only be 5-10% better, and you're testing on groups of 10-15 people for 8-12 weeks, random variation can easily mask or exaggerate effects.

Think about it: just by chance, one group might have slightly better genetics, better sleep, or harder work ethic. These factors create "noise" that can drown out the "signal" we're looking for. This is called sampling variance, and it's a huge factor in exercise science.

A massive meta-analysis on protein intake (66 studies, 2,665 participants) found that in 92% of individual studies, the effect of extra protein wasn't statistically significant even though we all agree protein helps. The same principle applies here. You need lots of data to consistently detect small effects.

So when you see studies going back and forth, that's actually normal. It doesn't mean lengthened partials don't work it means the effect is small enough that not every small study will detect it.

The Bottom Line

Lengthened partials are a legitimate technique backed by a reasonable amount of research, particularly for certain exercises like calf raises. They're based on the well-established principle that training muscles at longer lengths tends to produce more hypertrophy.

Should you completely overhaul your program? No. Should you panic if you've been doing full ROM? Absolutely not. Should you experiment with them on a few select exercises? Yeah, probably worth a shot.

My actual recommendation:

1. Keep doing full ROM on most exercises, especially those already challenging at long lengths

2. Consider lengthened partials for calves (strong evidence)

3. Maybe try them on leg extensions or leg curls if your equipment makes sense

4. Don't stress about it too much

And most importantly: if someone tries to tell you that you MUST do lengthened partials or

you're leaving gains on the table, they're overselling it. If someone tells you that lengthened partials are bro-science nonsense, they're not reading the research.

The truth, as usual, is somewhere in the middle: NUANCE is king.

Now stop reading and go lift something heavy (through whatever range of motion makes sense for the exercise).

References & Further Reading

For the nerds who want to dive deeper:

• Wolf et al. Meta-Analysis on Range of Motion

• Wolf et al. Lengthened Partials in Trained Individuals

• MASS Research Reviews - The best resource for in-depth research analysis

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