The Great R.O.M. Debate

 In our latest issue if Inside Fitness, we brought you a killer article from Inside Fitness advisory board member, James Grage breaking down the differences between Full Range of Motion vs. Partial and which (if either) is better. Unfortunately, due to the nature of print, we weren’t able to share that story in as much detail as we’d like. Thankfully, what print can’t do, digital can. We’re proud to share with you the original, full-length article. So, without any further adieu let’s get to The Great R.O.M. Debate!

Written by James Grage

So, what’s better for building muscle: Full Range of Motion (Full ROM) or Partial Range of Motion (Partial ROM)? This has been a highly debated topic amongst gym bros, content creators, research professionals, academics, and professional bodybuilders alike, going back longer than I can remember - and I’ve been doing this for a long time.   

Your experienced gym bros will often say that the academics don’t know what they’re talking about because they spend more time in the library than they do in the gym.  I’m sure on the other side there are plenty of academics that feel that the bros are too locked into dogmatic “bro science” and aren’t bothering to look at more evidence-based training strategies. There are even the individuals who have both an academic background and are experienced lifters;  you’d think they’d all at least agree on this topic - but even they don’t. 

One side will argue that they know the truth and everyone else doesn’t know what they’re talking about.  Ironically, the other side happens to be saying the exact same thing (so at least they agree on that, ha.).  The reality is this debate is probably a lot like the old adage, which goes something like this, “There’s always two sides to every story, and the truth is usually somewhere in the middle”.  So, let’s look at both sides and see if there are some truths somewhere in between.

FULL RANGE OF MOTION

Let’s first look at the rationale for using full range of motion.  This philosophy isn’t all broscience.  Sure, Arnold Schwarzenneger was a big proponent of full range of movement, which has often been depicted in photos of him doing dumbbell flyes with such a huge stretch at the bottom, but this idea is also supported by some of the most respected organizations in the world.  For example, textbooks from the National Strength and Conditioning Association state, “When the entire range of motion (ROM) is covered during an exercise, the value of the exercise is maximized” and then goes on to say, “Ideally, an exercise’s full ROM should mimic the full ROM of the involved joint or joints in order for the greatest improvements to occur”.  

There have also been numerous studies conducted comparing Full ROM to Partial ROM and found that full range of motion resulted in statistically significant differences in muscle growth.  Now keep in mind, “statistically significant” may sound impressive but really that just means that there was a measurable difference, and that doesn’t always mean that it translates to noticeable differences in muscle size or strength in the real world.   I also think it’s important to note that studies don’t always include all the right variables or comparables.  For example, if we’re going to compare Full ROM vs Partial ROM, then which range of the movement are we going to use for the partial?  For example, if we’re doing leg extensions for our test, then the partial range of motion could start at 100 degrees flexion at the knee and go to 50 degrees, what we would call the “bottom half of the movement” where the quadriceps is in its most lengthened position.  It could also be the top half from 50 degrees to zero, where the quad is in its most shortened position, OR it could even be the middle, say 75 degrees to 25 degrees.   

These variances can have a big effect on the results due to differences in muscle fiber recruitment at different muscle lengths.  Now, I’m not going to dive too deep into complicated topics like “muscle length tension relationship” but let’s just say that there’s good science that shows that there may be greater muscle fiber recruitment and greater muscle force production when a muscle is in a lengthened or slightly stretched position. In other words, if you’re doing the opposite, training with partials where the muscle is in a more shortened length, then there could be less muscle activation. 

This was the case with several studies comparing Full ROM to Partials.  The group that performed partials did them in the range where the muscle was in a shortened position - not in the lengthened position.  Long story short, the way those studies were designed may have put the partial ROM group at a slight disadvantage.

Another argument in favor of Full ROM is that when training in partial ranges of motion, the whole length of the muscle may contract, but that doesn’t mean that all the individual motor-units within a muscle are being fully recruited.  A simple analogy would be to compare a muscle to an engine in a truck, and the motor units would be the cylinders.  Let’s say that the truck has 8-cylinders but it has an eco-mode where it will only run on 4-cylinders when possible, to conserve fuel.  It’s only going to fire all 8-cylinders when the workload warrants it.   In order to fully recruit all the “cylinders” of a muscle, it is important to train a muscle through its full range of motion in order to fire all those muscle units.

There’s even a valid argument that greater range of movement also equals greater overall workload. Think of pushing that same truck if it ran out of gas.  Which is more work - pushing it 2 blocks or pushing it 4 blocks?   This is the concept of force multiplied by distance, which results in greater volume, which is another factor for muscle growth.   So greater workload may equal greater hypertrophy in the muscle (growth).   

Now there’s no science that proves what I’m going to say next (although there’s not much concrete science that proves ANYTHING related to muscle building - just a lot of ideas) but any very experienced lifter is going to tell you that the extra squeeze and peak contraction they get at the end of a movement absolutely makes a difference.   Whether it’s simply the extra isometric squeeze that you’re getting or the fact that you’ve literally contracted the muscle to the end of its range of movement, intuitively you know that you’re really working that muscle to its fullest.  All science aside, I am a big believer in using intuition in your training.  The amazing machinery that makes up our own body is far smarter than we are - learn to listen to it.

PARTIAL RANGE OF MOTION

So, let’s now talk about the other side of the story - the argument for partial range of motion.  Just like full ROM there’s evidence in both the world of bros and academia that support the idea that partial range of movement may have some advantages, even possibly over full range of movement.   Old school bodybuilding legends like Mike Menzter and Dorian Yates were known to have implemented partial rep training strategies into their training regimen, as well as many modern-day bodybuilders.  There also happens to be compelling evidence from a science perspective that supports the idea.

One of the most common arguments relates to the contractile units of the muscle, or the machinery if you will, of what makes a muscle contract or shorten in length.   There’s data that shows that this “machinery” (called the sarcomere) is strongest in the middle range of a contraction and weaker at both the beginning and end.  (If you’re interested in geeking out on the science you can look up “sliding filament theory” and “actin and myosin overlap”).   This has led many to theorize that there’s no need to train the muscle through its full range of motion and it’s only necessary to train in this middle range.   

Now the one problem I see with this idea is that this idea may be true for an individual sarcomere, but that doesn’t necessarily mean it translates to a full muscle.   There can be more than 100,000 of these sarcomeres in a single muscle cell and more than 250,000 muscle cells in a single muscle such as the biceps.  You don’t need to do the math to understand that is a shit-ton of these little contractile units all working in concert together to take a muscle through its full range of motion. 

Therefore, I find it difficult to believe that a muscle moving through its natural range of movement is going to have these glaring weak points, where it’s no longer worthwhile to train in that range of movement. Nature is a better engineer than that. A muscle is obviously fully capable of contracting strongly at both the beginning and the end of a movement, so in my opinion it’s very debatable whether this argument holds any value in a real-world training environment.    

Now there has been one study, published in 2017, in the Journal of Strength & Conditioning Research that compared full range of motion to different variants of partial ROM.   What made this particular study different was the thoroughness of including all different ranges, variants and combinations of movement to compare against full range.  In this study they found that partial ROM, with longer muscle lengths, resulted in greater muscle growth than the full ROM group.  Results also looked promising for combining Partial ROMs at both long muscle lengths as well as shorter muscle lengths.  Imagine doing squats one day only in the lower half of the movement and then the next leg day doing partials in the upper range of the movement.   Now although the study showed some promise for partial ROM training, it’s still only one single study and it needs to be replicated, requiring additional studies from other groups.

Another argument for partials is that if you train in a range of motion where you’re stronger, then you can use heavier weights, more mechanical tension, more stress to your nervous system, and therefore more possible growth and increases in neural strength. The counter-argument to this would be that if you’re lifting heavier weights then you’re also increasing risk of injury when you could potentially get the same muscle building benefits using slightly lighter resistance levels but increased volume through full ROM, and not have the same risk for injury.  Some of this risk could be offset by the fact that the range of motion where you are at most risk for injury is often when a muscle is in its fully stretched position.  For example, most of the biceps tendon tears that I see are when the arm is fully extended in say a preacher curl, as opposed to the peak of a contraction or even midway through. If your partials only included the middle or upper range of movement then you would be avoiding this possibility.    

The last, and possibly the best argument for partials is that by training in the middle range of the movement; with many exercises (not all) you are keeping constant tension on the muscle, never giving it a chance to rest at the beginning or end.  This constant tension not only ups the intensity of your workouts but it forces you to control your negatives (eccentric contraction), having to slow the weight and bring it to a stop while under tension and then start the concentric phase.  Think of it this way - the weight is trying to forcibly lengthen the muscle while you’re trying to contract and shorten the muscle.  This can create a lot of stress and damage to the muscle, which can be more stimulus for muscle growth.  Keeping the muscle under constant tension, with no rest at the top or bottom, also gives you greater Time Under Tension in the muscle, which is a key contributor to muscle growth.  That constant tension tends to trap a lot of blood in the muscle, along with a build up of metabolites like lactate, which acts as a signal for hypertrophy.  Now keep in mind that as lactate levels rise, the ph balance of the muscle becomes acidic and that’s why your muscle starts to burn.   So that burn does relate to muscle growth but it also requires some mental grit and toughness.

WHICH IS BETTER?

So, at this point, you may be thinking it’s no wonder there’s so much confusion around this topic. Top level athletes disagree, fitness experts disagree and there’s no clear answer from a science perspective. So, how should you be working out? 

Well, like we talked about earlier, I believe the answer is somewhere in the middle. Now, this is just my personal opinion, based on my personal experiences in 30+ years of training combined with a lot of research, discussions with experts through the years, together with a ton of good old-fashioned trial and error to figure out what worked best for me. Now opinions are like a-holes - everyone has one - so this is mine for what it’s worth.

First off, I don’t believe there’s only one way to achieve something. If someone chose to only do partials in all their training, they could probably get great results. I also believe that someone doing only full range of motion can get equal results. However, I don’t think the answer is so black and white and I think there is a lot of benefit in combining the best of both.   

I personally believe in using a modified form of full ROM. Let me explain. You don’t have to train the “full range of motion” of the joint in order to train the full effective range of motion for the muscle. It’s important to train in the range of motion where you have ideal tension in the muscle and within a range of motion that doesn’t cause strain or overstretching.  This range of motion is where there is the most mechanical tension, or when the muscle is exerting the most force. In other words, training the muscle at longer muscle lengths, but not overstretching the muscle where there is an increased risk of injury. 

A good example would be preacher curls. There’s no need to fully extend your arm at the bottom. I don’t believe there’s a muscle-building benefit to doing it and definitely a high-risk for a tendon tear. In other words, low return and high-risk. I would say the same about Arnold’s chest flyes. I personally think he could have built the same massive chest with less risk for injury.  His huge chest had less to do with his technique and more to do with his exemplary drive and work ethic, combined with great genetics - not from getting extreme ranges of movement in his exercises.

Now, although I don’t believe it’s beneficial to train in this overstretched position, I don’t buy into the idea of avoiding the extreme peak of the concentric contraction. There’s little to no risk in doing it and only potential benefit, so why rob yourself of that. The only thing to be conscientious about is making sure that you’re focused on that full range of motion where there’s ideal tension on the muscle.  

If you’re doing chest flyes as an example, there’s no need to move your arm so far across your body past the point of your chest being fully contracted.  Once that muscle is in its peak contraction there’s no reason to go further than that. The moral of the story: you don’t need to focus on extreme endpoints.  

Another reason for a modified version of full ROM is the same argument I would use if I were in favor of partials, which is the benefit of constant tension and controlled eccentrics. By stopping just short of the bottom you’re still getting that same benefit of partials, while also getting the benefit of the increased muscle length (muscle length/tension relationship).  Combine all this with full recruitment of all motor units and the increased workload, you now have the best of both worlds.   

With all that being said, most of your muscle building results, and injury prevention are going to come from disciplined form, hard work, consistency, and some good old-fashioned grit.   There’s no amount of science that can shortcut that.

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