On any given day, if you really take a moment to notice what everyone else is doing in the weight room, you will find folks performing a variety of routines, using different numbers of repetitions and sets, different exercises, and different form, like full reps vs. partial reps. What’s so interesting about exercise (and, well, nutrition for that matter) is that some exercises go in and out of favor.
For example, think back to the 1980s when aerobics were in style… think Jazzercise and spandex. Or, maybe not, that’s not an appealing visual.
Moving into the 1990s, fitness videos like Tae Bo and home gyms, like Bowflex were all the rage. The early 2000s brought us P90X and Insanity which emphasized functional, high-intensity training. And, now, we have spinning, yoga, CrossFit, Barre, Zumba, and the list goes on. Between all of these training styles, we often find mutations of sorts, where folks will follow the general premise of the style of training they prefer with some modifications.
My long-winded point is this: it’s hard to keep up with all these trends. The fact that you’re seeing more and more folks not performing reps at their fullest range of motion is not surprising. This has gone in and out of favor since bodybuilding was all the rage back in the 1970s.
Why Perform Partial Reps?
I’ll start by saying there may be good reasons why folks only perform partial reps. Performing a movement through its full range of motion can be painful. For example, when I first train someone to perform a standing squat using just their body weight, I may not have them perform a deep squat so their bottom touches the ground before they stand back up. Instead, I may have them stop halfway so that their bottom is parallel to the ground as if they were attempting to sit in a chair.
This is because it may be too painful or too much stress on their knees to perform a full deep squat. The same goes for performing bench or chest press. I often don’t have folks lower the barbell or dumbbells all the way to their chests; it may place too much strain on their shoulders and elbows. Partial reps can be a nice way to ensure safety and prevent injury or further damage if the person is training after an injury.
But let’s say you do have the ability to use your full range of motion without any aches and pains. Would it provide you with similar strength gains?
What’s unfortunate is that there aren’t many published studies examining the effects of partial reps vs. full reps and strength gains. Much of it has been anecdotal. You’ll get so-called experts talking about the benefits of partial reps based on their experiences training others. But if this analysis is not done systematically, all sorts of biases can pop up.
Some exercise physiologists believe that performing partial repetitions is ideal because it forces you to engage your muscles through that entire repetition. When you reach the full range of motion, the argument is that you’re not engaging your muscles at the very top or at the very bottom of that movement.
Using my example of performing a squat, if we were to perform squats using the full range of motion so that our bottoms have to touch the ground with reach rep, would we really be engaging our muscles at that moment when our bottoms actually touch the ground? Some say, no–that at the point our bottoms touch the ground, we are no longer engaging our leg muscles (more specifically, the quadriceps).
I will say that this is a bit short-sighted. Performing repetitions through their full range of motion, when it’s safe to do so, can potentially prevent injury and promote flexibility.
When it comes to whether strength gains are comparable using partial reps when compared to full-reps, again the data are limited. First, there aren’t many published studies, and second, those that have been published are performed with only a few individuals and for a short period of time. Furthermore, they only examine one or two moves like bench press and squats for example. They don’t study how it effects shoulder presses, or one-arm rows, or lat pulldowns, or exercises performed using machines. We really can’t say with any confidence how effective partial reps can be.
The Bottom Line
If you are willing and able, aim to perform exercises using the full range of motion. If it is uncomfortable to do so, go as far as you can through the range of motion, but stop before you feel discomfort. Then gradually see if the discomfort goes away with time and practice. If it does, increase your range of motion and again stop when it feels uncomfortable.
The key is to concentrate on the work you’re doing–imagine your muscles getting stronger as you perform each rep. Think about how this exercise is going to help you feel your best. This way, you’ll be in tune with your body as you perform every single repetition of every single set to minimize injury, maximize your gains, and help you feel your best.