Quality Of Reps VS. Quantity Of Reps

For quite a while now, it has been the consensus by both professionals and researchers in the fitness industry that performing exercises with full range of motion (FROM) is superior to doing them with a partial range of motion (PROM). Despite this, if you go to any gym, you will likely see a large number of people doing dozens of fast half-repetitions (reps) or even quarter-reps on all of their exercises. When I was speaking about this topic to someone at a gym I visited, he told me emphatically that all that matters is lifting heavy enough to get the “pump” and that what you read in the textbooks doesn’t actually carry over to real life application. In this article, I will explain to you why FROM is superior to PROM, while also considering any of PROM’s possible benefits.

PROM VS. FROM

First, to gain a basic understanding of the underlying principles behind range of motion (ROM), we must understand the physiology involved. Within the muscles, there are motor units, which you can think of as “gears” that spin when you contract a muscle. These motor units exist throughout the muscle and each works interdependently to the others. This is important because it shows that, if you were to do an exercise with PROM, you wouldn’t be activating all of the motor units. This can be detrimental to both strength and hypertrophy (muscle building) in the long run. In order to get the most out of each exercise you do while getting the maximum amount of motor units to activate, you need to go through the FROM. Dr. Mike Israetel explains in one of his videos that, by using FROM, “all of the motor units on the muscle get hit, all of them potentially grow,” going on to say that doing PROM is “screwing yourself over by not targeting parts of the muscle.”

Another factor to consider is volume. Many people, such as the gym-goer I mentioned before, make the argument that when you do partial reps, you are able to lift significantly heavier weights. Of course, one of the main drivers of muscle growth is the total amount of volume, which is your workload throughout the week and is generally measured in sets per muscle group per week. Volume can be increased by doing more sets, more reps per set, lifting more weight for the same number of reps, etc.: anything that increases the overall amount of work the muscle group does throughout the week. This means that logically, lifting heavier while using PROM sounds like it could be beneficial. However, in reality, doing PROM decreases total volume. Israetel gives another great description to explain this; volume is literally “the force times distance,” meaning that by decreasing the distance the weight is traveling, you’re significantly lowering the overall work generated, creating less total volume.

Mechanical Tension In Practice
Not only are partial reps not as beneficial to volume as reps done with FROM, but they are also less effective at creating mechanical tension. In The Mechanisms of Muscular Hypertrophy by Dr. Brad Schoenfeld, Schoenfeld characterizes mechanical tension as one of the three main muscle building mechanisms. Dr. Bret Contreras, writing to expand on Schoenfeld’s article, explains that mechanical tension is caused in the two main phases of the ROM, the stretch and the flex. This follows the common theme in Scott’s videos in which he emphasizes the importance of the stretch and flex in each rep. Contreras explains that the reason this is so important is due to the presence of passive tension in the stretch portion of the rep and active tension in the flex portion. Basically, if you were to exclude either of these potions from the rep, you would be missing out on either the passive or active tension, creating less total mechanical tension.

Although this all makes sense in theory, it’s important to look into whether it actually works in practice. In an article written by Dr. Brad Schoenfeld, two studies done on ROM were cited. In the first study, the subjects either did partial or full reps of preacher curls, while also making sure to have them employ progressive overload by increasing the number of sets and decreasing the number of reps. The group that had done FROM achieved significantly more muscle and strength increases than those doing PROM over the 10-week study, even though those doing FROM had less total training volume. In the second study, subjects were told to either do deep squats or shallow squats. Heavier loads were used in the shallow squat group to equate volume. In this study, the subjects doing deep squats saw statistically significant increases in the lean body mass in their legs. Overall, Schoenfeld concluded that “greater ROM produces more complete overall muscular development.”

Can PROM Be Advantageous?
Despite the obvious advantage FROM has over PROM, there are instances in which adding in some PROM exercises can actually benefit your program. For example, in doing Cheat and Recover, a method off of which Scott has built an entire program, you skip the concentric phase of the movement in order to overload the eccentric phase. In a bicep curl, this would look like cheating the weight up and then lowering it down slowly. Cheat and Recover takes advantage of the fact that our muscles are approximately 40% stronger in the eccentric than in the concentric. Generally, it is difficult to overload the muscles in the eccentric phase when using a weight that can be handled properly in the concentric. Another example of this is lifting in 21 rep style, in which you lift 7 reps in the lower half of the ROM, 7 reps in the upper half of the ROM, then 7 full reps. Instead of just lifting in the bottom half, you will also be working the upper half of the ROM, which, followed by going through the FROM, still allows for activation of all the motor units within the muscle.

Another beneficial way to add PROM exercises into your routine is by using them to help strengthen a specific part of the ROM. If there is an exercise in which you have a sticking point, this is especially beneficial. For example, if you have a sticking point at the bottom of the bench press, meaning that you struggle to get the weight out of that position, training a couple of extra sets in the bottom of the ROM when you work out your chest can help to overcome it. This also applies well to exercises like side lateral raises or front delt raises, both of which are significantly harder in the second half of the movement. In this example, instead of adding extra sets on to the end of a workout, you can simply do 1½ rep style, in which you raise the weight to the top of the ROM, lower it halfway down and then bring it all the way back up before fully lowering it to the bottom. This also allows for a longer contraction and more time in the hardest part of the ROM, creating more mechanical tension and muscle damage.

Conclusion

In summary, both physiology and practical application have proved that FROM is more effective for building muscle and strength than PROM. Although PROM can be applied to a program consisting primarily of FROM movements to help overcome sticking points and strengthen ROMs where you are weaker, they should only make up a small part of your program.

References:

https://bretcontreras.com/training-for-maximum-muscle-growth-explained/
https://musculardevelopment.com/training/15566-partial-vs-full-range-of-motion-reps-which-is-best.html
https://www.jtsstrength.com/fitness-myths-with-dr-mike-partial-range-of-motion/
http://img2.tapuz.co.il/forums/1_158907702.pdf