The first thing you need to understand is what exactly is Range of Motion. ROM is basically how much you can stretch a muscle to its maximum, and shorten it to its maximum. Each muscle of our body has one specific position where it reaches its maximum stretch, and another specific position where it reaches its maximum shortening. Now the question is: Why is this important in my training? The answer is not so simple.

When you talk about bodybuilding and training your muscles, wherever your objectives are, you need to train them where they are the WEAKEST. But where would be this point of weakness? In the extremities of the ROM. Our muscles have one “Strength Curve” like this here:

Let me explain you quickly. The muscles are composed of muscle fibers, where inside them we can find filaments of myosin and actin (two proteins), which will slide over each other to make the muscle contraction. 

This is a really simple explanation of a muscle contraction, so you can understand what I will say. In that strength curve picture that you saw, you can notice that the muscle relaxed has no power of contraction, then it reaches its peak, and then the curve descends again. There is a reason for that. In the beginning, where your muscles are fully lengthened, there is not much contact between actin and myosin filaments to produce contraction. Automatically, there is no contraction. You will start shortening your muscle, it will reach its peak of contraction, the curve will rise and will descend again, because there will be too many fluids inside the muscle fibers after one certain point of the contraction, pushing myosin and actin apart, and there will be no room for shortening anymore, making the muscle contraction weaker again.

Contracting and stretching your muscles to the maximum will make sure that you will break more muscle fibers, stimulating more protein synthesis to repair those fibers broken, consequently making the muscle grow bigger and stronger. Is that a definitive answer though? No.

According to Newmire DE, Willoughby DS et. Al 2018, “there is not a definitive consensus on optimal range of motion. It appears that the partial range of motion (pROM) mode of exercise may have some similar benefit on muscle hypertrophy as the conventional full range of motion (fROM)”. 

In the other hand, Schoenfeld BJ et. Al 2020 found that “When assessing the current body of literature, it can be inferred that performing RT through a full ROM confers beneficial effects on hypertrophy of the lower body musculature versus training with a partial ROM. Alternatively, research on the effects of ROM for the upper limbs is limited and conflicting, precluding the ability to draw strong practical inferences.”

My conclusion considering science and my own experience in the weight room: there is a correct moment for everything, and there is a reason why for everything. In terms of functionality and longevity, I don’t see much of a benefit on training in a shortened range of motion. It can actually be detrimental in terms of strengthening the muscles only in that portion of the range of motion, where that person is already strong. Every limitation (mobility and flexibility), since it wasn’t achieved through an injury or accident, is just your body telling you “I don’t feel confident to work beyond this point”, so it is extremely interesting for the trainee to increase their mobility/flexibility levels and start loading those points of the ROM where they used to be weak. That will grant them a whole new perspective regarding quality of life (high performance athletes included, with the objective of preventing injury).

From the hypertrophy point of view (and I mean maximal hypertrophy, not the “50 year-old who wants quality of life” hypertrophy), there can be a benefit to a shortened range of motion during training, but I, Bryan, still prefer to keep most of the training in full ROM (and I mean “useful” range of motion, where you can stretch without breaking form), and utilise specific techniques in short range during specific moments of the training periodisation, that way the trainee won’t lose their capacity to stretch that muscle group, and will also take advantage of the benefits of a shortened range of motion during training.

*sources: Fox’s Human Physiology 12th Edition – Stuart Ira Fox

Schoenfeld BJ, Grgic J. Effects of range of motion on muscle development during resistance training interventions: A systematic review. SAGE Open Med. 2020 Jan 21;8:2050312120901559. doi: 10.1177/2050312120901559. PMID: 32030125; PMCID: PMC6977096.

Newmire DE, Willoughby DS. Partial Compared with Full Range of Motion Resistance Training for Muscle Hypertrophy: A Brief Review and an Identification of Potential Mechanisms. J Strength Cond Res. 2018 Sep;32(9):2652-2664. doi: 10.1519/JSC.0000000000002723. PMID: 29985227.