Fitness is science: How and why does the range of motion in any given strength exercise matter?.
Let us dive down into a range of motion and squat study.
Right now, if you enter any given gym, the wonderful world of barbells and healthy fit living will conjure up as many opinions as there are fitness girls on Instagram, no matter the subject.
And plenty of opinions are exactly that, personal opinions, formed by peer pressure in the gym, on social media, or by fit vixens looking to make a bigger following by posting daily stuff which may or may not be factually correct.
There are out of date school gym coaches still living in the past, badly informed parents, friends, big brothers, big sisters, commercial interests only looking out for the next conference call, as well as uninformed health experts, pt´s and writers working for big tabloids which just happened to draw the assignment to make a puff piece on fitness.
So let us instead look at current fitness science and what it actually has to teach us about the range of motion for any particular exercise. And for the purpose of this article, let us focus on a Squat centric use case since legs and ass are thankfully all the rage anyway :).
And to do this, we´ll load up some decent weights on a barbell and take two groups of people and have them train squats seriously 3 times per week for 12 weeks in total.
And while they do this we´ll measure not just their strength development but their actual hypertrophy and lean muscle mass progress too before we make a nice little summary at the end of it all.
The only difference between these two groups is the length of the actual squat.
One group will do a full range of motion squat, sitting as far down as 120° of knee flexion, while the other group will reach their bottom level at roughly 60° of knee flexion.
In reality, when you are at the gym doing your own squats this would mean that the 120-degree group would have their upper thigh (femur ) parallel to the floor, which is about as low as you should go. There is really no need for most people to do ass to the grass squats as far as hypertrophy and strength development goes, unless you have a specific sport related reason to go ass to the grass.
There is most of the time nothing wrong with going that deep, except that doing ass to the grass squats can increase injury risk by a little bit, and perhaps, especially so for the lower back area, and while we all love progress and pushing it in the gym, injuries are best left alone.
Not to mention that they have a tendency to flatline your progress so to say.
As such, my own recommendation for the deepest part of the squat is for most clients about the 120-degree mark.
The full range of motion party increased their strength with 20% across the entire range of motion, and the other group increased their strength with 36% across the more limited range of motion ( but only 9% across the entire range of motion ).
Other measurable observations are that the full range of motion group increased lean muscle mass in the entire quadriceps to a higher degree than the limited range of motion group managed to do.
“Training deep squats elicited favorable adaptations on knee extensor muscle size and function compared to training shallow squats.”
Making it more or less a clean sweep for the full range of motion group, right?.
And that almost is equally important to take with you when we conclude the scientific reason why the range of motion matters when you are at the gym and why you should probably include both. So continue reading to get the low down of it all.
Most of the time you should thrive to do your exercises with a full range of motion because it forces the targeted muscle(s) to develop their strength and fat-free muscle mass in the entire range of motion and the entire length of the muscle itself.
Which is obviously not just good for your progress but it also eliminates weak points in real life movement and thus, lowers the risk for injuries to develop.
But, this is where the proverbial but also happens to show up.
And this time our cute little but has to do with the fact that the limited range of motion group managed to increase their strength levels within that limited range of motion far more than the full range of motion group did ( while developing their strength in the full motion range to a lesser degree ).
In other words, there are obvious but highly specific strength gains to be made from training with a limited range of motion for certain periods or just a few sets per workout.
But never do so at the expense of getting your full range of motion reps in, unless you have a very specific use case tailoring your workouts for a set period of time. Perhaps lifting weights is just one compound in your pro sports career, and in that case a limited range rep might be what suits your specific sport the best for a specific amount of time.
One such example could be an ice hockey player, or a MMA fighter.
And in that case explosive and heavy high rep squats with a limited range of motion such as Anderson squats in combination with a seriously overloaded barbell might very well push your fitness levels and explosive strength through the roof in ways that would benefit your specific sport-related performance in a useful way, far better than doing full range of motion squats might ever be able to do. But consequently training with a partial range of motion all the time will also increase the risk for injury by quite a margin, so you are more likely better off mixing your range of motion even in the case of pro athletes specific needs.
In other words, generally speaking, even pro athletes should make sure to get some full range of motion sets in their workouts too, just to make sure that they develop their entire range of motion strength and decrease the chance of developing injuries and muscular imbalances. After all, injuries will shorten any pro career no matter talents, genes, stubbornness and sport so while we chase progressive improvements and PB´s, staying healthy and injury free is without a doubt the best way to keep on improving.
Allowing us to wrap this up with this short summary.
Summary: Most people should almost always do full range of motions exercises, but everybody can benefit in clear measurable ways from some amount of limited and heavier, range of motion training.
And if you have specific sports or health-related needs that also factors in.
And for the gym people that´s quick at shooting down others execution and knowledge whenever they see something that is outside of their own perceived norm. Next time around, if you see an obviously fit person performing partial reps try to keep in mind that they are most likely just executing an advanced fitness plan.