Training at Long Vs Short Muscle Lengths For Hypertrophy
Does more range = more gains?
Spark Notes:
Training at longer muscle lengths tends to promote more muscle growth than when training at shorter muscle lengths
Biarticular muscles (meaning crossing two joints) such as the hamstrings, allow for us to manipulate multiple joints to change the length that muscle is trained at
When directly comparing seated leg curls to lying leg curls, seated leg curls caused more hypertrophy in all the biarticular hamstrings muscles in untrained lifters
This doesn’t mean we should never train at short muscle lengths
If we do train at short muscle lengths, it’s important that position is still loaded (Squats vs leg extensions)
When it comes to training for maximum muscle gains, range of motion always enters the discussion.
Based on the evidence we have to this date, I would say that training with longer range of motions and therefore longer muscle lengths, seems to be the better option here.
What I will say though, is that this probably shouldn’t be a hard rule all of the time.
More appropriately, this is general framework that is supported by the literature.
An example being above. A recent meta-analysis of studies comparing differing range of motions between groups and the hypertrophy outcomes of them did show full ROM to be superior.
The pooled effect size for lower body hypertrophy outcomes was 0.88 in favour of full range of motion training. Which would be considered a “large effect”.
With that being said, you will notice some outcomes did in fact favour the shorter ROM interventions.
All in all though, you will see the overwhelming amount of outcomes were better in the full ROM interventions.
So it is safe to say that in general, longer ranges of motion tend to be superior to shorter ranges of motion for building muscle.
With that out of the way, I wanted to breakdown a cool study that directly compared this with the seated and lying leg curl machine for hamstrings hypertrophy.
The reason this particularly interesting, is that the hamstrings for the most part, are a biarticular muscle.
This means they cross two joints and therefore can act on two joints. The two joints being the hips and the knees.
Because of this, they are hip extensors and knee flexors.
Well, all but the biceps femoris short head, which you can see only crosses the knee joint. This means it can only help out with knee flexion.
An easy way to remember this is hip extension would be a Romanian deadlift & knee flexion would be either the seated or lying leg curl.
Considering that the hamstrings are a biarticular muscle, this allows us to train them at different lengths quite easily and through a full range of motion for that particular exercise.
A lying leg curl would lengthen the hamstrings via knee extension (straight knees) and through minimal hip flexion.
But a seated leg curl would lengthen them fully through a combination of full knee extension and deep hip flexion.
As seen above, the seated leg curl would train the hamstrings (except for the short head of the biceps femoris) in a longer position.
This brings us to the study at hand. As it directly compared the two exercises and how they impacted hypertrophy on the hamstring as a whole and between individual muscles of the hamstring.
The differing factor here is that both exercises are taken through a full range of motion, but due to the position of the hips, they are at different muscle lengths for the hamstrings.
An alternative example is doing half squats vs full squats. It’s the same exercise, but the range of motion is just shortened in the half squats.
Full squats tend to be better than full squats.
But this study compared two hamstrings exercises that are taken through a full range, with the only difference being the actual muscle length of that given exercise.
Let’s see how it panned out.
Study Reviewed: Greater Hamstrings Muscle Hypertrophy but Similar Damage Protection after Training at Long versus Short Muscle Lengths
This study had 20 participants who were deemed “healthy” but had not been regularly resistance training for the last year.
So for all intents and purposes, this was on untrained subjects.
This is important to bring up since we can’t guarantee the same outcomes would happen in more trained lifters. Although, I’m not sure we’d expect drastically different outcomes here.
With that, all subjects had one leg randomized to do either exercise during the trial.
For the seated leg curl, the hip joint was fixed at 90 degrees and for the lying curl, the hip joint was fixed at 30 degrees. Keeping in mind that 0 degrees is anatomical position.
End range for knee flexion was 90 degrees to standardize range across the board.
Here is a breakdown of how the training program went:
The measurements to assess muscle growth were from using MRI. They measured the whole hamstrings muscle and also the individual heads.
Other muscles were also measured but we’re going to stick to the hammies here.
Results
When it came to the results of this study, they were pretty on par with what we’d expect.
As mentioned above, training with longer ROM tends to be better than training with a shorter ROM for building muscle.
This was the case here in regards to the whole hamstrings muscle.
See below.
The average increase in muscle volume for the seated curl was 86.7 CM cubed, which was a 14.1 % increase.
The average increase in muscle volume for the lying curl was 56.8 CM cubed, which was 9.3 % increase.
Both increases were statistically significant from baseline, but the difference between groups was also statistically significant in favour of the seated leg curl.
When it came to each head of the hamstrings, all the heads that were biarticular did favour the seated curl over the lying curl.
As you’ll see, only the short head of the biceps femoris had similar increases in hypertrophy with both groups.
Which isn’t surprising since it’s only a knee flexor. Making hip position irrelevant to taking the short head through a full range of motion.
Takeaways
When it comes to takeaways from this paper, an easy one is that if you want the most bang for your buck when it comes to growing your hamstrings, the seated leg curl is probably your best option.
The hamstrings are also hip extensors, so of course you’ll still want to train your hamstrings with movements such as Romanian deadlifts.
But keep in mind that there are several other large and strong hip extensors that the hamstrings will be competing with in hip extension movements. Such as the glutes and the adductor magnus.
So if you feel you really need to beef up your hammies in particular, then you’d be wise to train them through knee flexion.
The calf will also be competing with the hamstrings for knee flexion, but research has shown that the strongest position for the calf to act on knee flexion is when the knee is extended. From there calf activity dramatically decreases during the first 15 degrees of knee flexion and continues to at a slower rate as the knee continues to bend.
So in summary, when it comes to training your hamstrings, knee flexion is a great option to isolate them better.
From there, when training the hamstrings with knee flexion, the seated leg curl seems to have the upper edge.
Now, with that in mind, this doesn’t mean you should never use the lying leg curl.
Remember, the seated leg curl does train the hamstring in the more lengthened position, but it also keeps your hamstrings in hip flexion.
This doesn’t allow for your hamstrings to fully shorten.
While the lying leg curl doesn’t allow you quite fully shorten your hamstrings, it does allow you get much closer to the fully shortened hamstring position.
In fact, it seems to be the shortest position you could realistically train your hamstrings in.
And for building general tolerance of your tissues and joints, I do think it’s wise to train your muscles through diverse ranges. This would include also taking a muscle to it’s shortest position — even if it isn’t the absolute greatest position for peak hypertrophy gains.
I think this especially matters more if the shortest position is still loaded. Which it is in both the lying and seated leg curls.
This is why machines can be so useful.
Let me use an example with training your quads.
When it comes to training your quads, I assume you’d think of an exercise like the squat.
Which is cool because it’s a great exercise.
But it doesn’t load the shortened position of your quads really at all.
If we look at the example above, we’ll see the bottom of the squat (lengthened position of the quads) and the top of the squat (the shortened position of the quads).
As we can see, the quads are only loaded when in the lengthened position here.
The beige line represents the line of force and the white dot and smaller dots represent the perpendicular distance from the joint being loaded (the knee) and the line of force.
This is otherwise known as the moment arm.
At the top, zilch. At the bottom, gainz.
If we compare this to say, the leg extension, we get an entirely different story.
We can see the moment arm is the same in both the long and the short position of the quads here.
One caveat is that this does not mean the line of force is equal in both positions. That would depend on the shape of the cam. Which is the oval-ish thing underneath my knee in the second picture with the yellow knob on it. The cable moves around the cam during the movement. The distance from the cable to the middle of the cam will dictate the load as well.
So with the squat, the short position has relatively no load placed on the quads, but with the leg extension it does.
This is pretty intuitive as we all know how easy the top of a squat is and that holding the top of a leg extension can be quite grueling.
With this in mind, we can see that both leg curls load the hammies in their short position, but the lying curl does so more.
We can think of the seated curl as being better for total hypertrophy and for loading a deeper stretch on your hamstrings. And we can think of lying curls still being decent for hypertrophy, but also exposing your hamstrings to load in their shortest position.
My final takeaway is that, this does hold up the idea that training a muscle at a longer length is better for hypertrophy.
You should keep this in mind when it comes to your training — especially if you want to build more muscle and expose your joints to deeper ranges.
I also hope this brought some more nuance into this conversation. Training in short positions is not useless. If that short position is unloaded or very minimally loaded (say a quarter squat), then it does become less useful.
But if that shortened position is still loaded (like in a leg extension), there is a use to it.
If you have access to machines and diverse ways to train your muscles, I’d advise using them.
Especially if you’re not a powerlifter (or other iron sport athlete) who inherently will have less room for variety with their competition movements taking priority.
Make sure you’re getting those precious gains, but don’t forget to explore the options within the gym.
Keep lifting and stay strong. 💪🏽
Cheers,
Coach Dylan 🍻
References:
1. Effects of range of motion on resistance training adaptations: A systematic review and meta-analysis
https://onlinelibrary.wiley.com/doi/10.1111/sms.14006
2. Greater Hamstrings Muscle Hypertrophy but Similar Damage Protection after Training at Long versus Short Muscle Lengths
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7969179/
3. The function of gastrocnemius as a knee flexor at selected knee and ankle angles
https://www.sciencedirect.com/science/article/abs/pii/S1050641102000494?via%3Dihub