What’s the Best Range of Motion for Muscle Growth?

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The term “range of motion” (ROM) has two main definitions:

• The displacement of the implement you’re using, which is the difference between Position A and Position B achieved by a barbell, dumbbell, or cable from the start to the end of a movement
• The extent to which a body part can move around a joint

 
As a muscle goes through its range of motion around a joint, it changes length from a shorter to a longer length, and vice versa. For this reason, the second definition of ROM is the more relevant to this article.
 
But why would you care about muscle length?

Interestingly, according to some emerging research, muscle length can affect hypertrophy.
 
And, by manipulating the ROM of any exercise, you can train at different muscle lengths.
 
Specifically, you can take an exercise through either a full ROM or through a partial ROM at two different muscle lengths.
 
Let’s use the squat as an example.

To perform a full ROM squat, you lower yourself down on your haunches as low as you can, thus lengthening the quads as much as possible, then stand up and straighten your legs fully, which in turn shortens the quads as much as possible.

As a side note, everyone has a unique build, so your full ROM can look different from someone else’s. For instance, not everyone can squat deeply enough to touch their hamstrings to their calves.

So, if you plan to take a movement through a full ROM, it’s important to figure out what your own full ROM looks like.

To perform a partial ROM squat, you can:
 

• Start in a standing position and stop half-way through the descent (the eccentric portion of the lift) before standing up straight again, thus training the quadriceps through a partial ROM at shorter muscle lengths; or
• Start from a half-squatting position and lower yourself all the way down to the bottom, also known as “the hole”, then push through the heels back up into a half-squat, thus using a partial ROM at longer muscle lengths.

 
In the first instance, the muscle fibres of the quads are shortening fully, but they’re not lengthening to the same extent because you’re only lowering yourself into a half-squat position rather than going “ass to grass”.
 
In the second instance, the muscle fibres have to lengthen completely at the bottom of the squat, but don’t shorten as much, because you’re not straightening the legs at the top of the rep.
 
So what’s the best ROM for hypertrophy?

A recent meta-analysis from September 2022 sought to address this very question.

In research, a meta-analysis can provide valuable evidence when conducted properly, as it aims to provide a high-quality summary of the results of all the studies conducted to date on a specific topic.

The results of this particular meta-analysis seem to be generally in favour of full ROM training for hypertrophy of both the upper and lower body.

As for partial ROM training, it seems like training at long muscle lengths may be equal to or better than full ROM training, and likely better than training at short muscle lengths.

However, only six of the 23 studies included in the review involved partial ROM training at long muscle lengths, so my current view is that we need more research to confirm these hypotheses.
 
Even so, these results paint a promising picture for partial ROM training at long muscle lengths, so I’ve already been implementing this method in my coaching practice for several months.

How can you apply this to your own training?

I don’t think you must choose between full ROM and partial ROM, as I’m not sure we have enough evidence to state with confidence that one is so superior as to make the other redundant.

Given these research results, a combination of full ROM and partial ROM at long muscle lengths seems to be a great strategy to stimulate hypertrophy.

In practical terms, you could take some exercises for a certain body part through a full ROM and others through a partial ROM at long muscle lengths: for example, you could program barbell squats with a full ROM in one quad session and Smith machine squats with a partial ROM at long muscle lengths in a different session.

In addition, you could try a higher-intensity technique I’ve been experimenting with in my own and my clients’ programs, called “lengthened” or “stretched” supersets, a term coined by Milo Wolf, one of the authors of the previously cited meta-analysis.
 
Lengthened supersets include a standard set of an exercise taken through a full ROM, immediately followed by a set of the same exercise taken through a partial ROM at long muscle lengths.

Lastly, although research appears to suggest that training through a partial ROM at short muscle lengths only may be less beneficial for hypertrophy compared to both full ROM and partial ROM training at long muscle lengths, I wouldn’t discard it altogether just yet, as we likely need more studies to glean greater insight into its potential benefits and uses.
 
Thanks for reading. May you make the best gains.
 
If you want to learn more about the practical applications of long muscle length training from none other than Milo Wolf himself, you’re in luck because I interviewed him in this podcast episode, which you can also find on all audio platforms by searching for the title “Fit to Transform Podcast”.
 
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