At most health facilities in the world if you were to look out on the weight room floor I’m sure of two things… people will be doing curls, and people will be doing partial range of motion. Usually these go hand in hand, but people can do partial range of motion (ROM) in many different exercises; the most common being pushups, squat, & pullups/chinups.
I’m sure many of you have great reasons for only doing half of the motion; starting back in the 80’s some research even came out to say that you can have the same benefits from doing half reps as the full rep. Many people say that their bodies react to it better, it’s safer on their joints, they are stronger and can workout harder etc. etc. Well let me tell you what the science says about partial range of motion exercises:
- Partial range of motion can be used to gain strength & size, especially if you have plateaued. They go on to state that it is not a workout regiment you do every day, more of a once every two weeks and it must be accompanied by a full range of motion exercise using the same muscle groups within the same workout. Partial ROM is also supposed to be utilized AFTER a base strength has been achieved!
- The strongest muscle fiber is a fully elongated (stretched) and fully hydrated. If we take that first concept, a fully elongated muscle fiber means working a muscle through the full ROM. If you do partial reps, you are strengthening only one half of the muscle fibers. Let’s take pushups, if you just push yourself up halfway off the floor, or only lower your body halfway down…what happens when you fall and need to catch your body with that muscle fiber that is never worked. My guess would be injury. This may not happen right away, but I guarantee if all you ever work is partial ROM severe injury will plague you at some point.
- What happens with muscle fibers that are continually contracted but never stretched or relaxed? They become very tight and shorten up. A prime example of this would be with the bicep curl. For those of you who curl the weight up to your shoulders and then as you lower it shoot your elbows backward keeping a large bend in the arm, you will end up with locked elbows. Ever see those people who cannot straighten their arms out all the way? Well your bicep can actually fuse to your arm if you do too many partial ROM exercises and never incorporate straightening your arms all the way. The only way to have this fixed once it happens is surgery where they have to tear the muscle off the humerus… doesn’t sound like too much fun to me! (Women are allowed to have a soft elbow, meaning an ever so slight bend in their arm, when doing curls because of a hyperextension issue only with females).
- Now the big question, squats…should someone go below parallel? Isn’t it bad on the knees? Here is my opinion on this topic; since the science goes back and forth with some research stating it is bad on the knees & others stating it is just fine. One…when we were born could we squat our hips below our knees? If you are ever in the SAC go check out the day care; I bet you a dollar you will see kids squat down their diapers below their knees to pick up toys! Two…look at other countries like China and Japan, everyone there sits with their knees below their hips to do everything. You will see people of all ages reading newspapers, eating, holding a conversation sitting in a deep squat. So if we were born able to do it and other counties do it (and they have a lot less knee/hip issues than the USA) I would assume it would be ok to perform a deep squat, but even smarter to utilize a trainer to help you get going first.
- Are there exercises it is ok to do partial ROM? Yes there are, but for the general population who workout in the gym, there is no need for them to do them; and if you really want to know what they are, come find me ill let you know which ones. A hint is they are usually associated with the shoulder complex!
All in all, if I was to recommend someone do partial ROM it would be to get over that plateau in strength, but I would still make them do that same movement full ROM within the same workout. Women may have a soft bend during curls to prevent hyperextension of their elbows; other than that there is no solid evidence of any full ROM exercise (to my knowledge) being a safety concern. If you have questions about your form on an exercise, grab a PFT in a red shirt and ask them to check out your form; we would gladly assist you in correcting any unsafe movements!