Lab Notes · 4 min read
People tell me they have gotten tight and they need to stretch more. The tightness is real. The tool is wrong. So here is what range of motion actually is, and where you get it back from.
Put your arm overhead. The furthest point you can reach is your range of motion at that shoulder. It is a place, and it is measurable.
Now ask the second question. At that furthest point, how much force can you produce? That is a different number, and on most people it is close to nothing.
Those two numbers are the whole subject. You can move the first one on its own and leave the second one where it was. A joint that travels further than your muscle can control is a joint your body has to protect, and the way it protects it is by refusing to go there. That is what tightness usually is.
When you stretch for a few weeks and your reach improves, the muscle has not gotten longer. What changed is the point at which the stretch becomes uncomfortable. Researchers call this stretch tolerance, and it is the mechanism they credit for the range you gain from a short stretching program.
Weppler & Magnusson, Physical Therapy 2010;90(3):438–449
That is a genuine change and it is worth having. It is also only half of the thing you came for. Your nervous system now lets you into a position you were kept out of, and you arrive there with nothing to do once you get there.
Strength does not spread evenly across a joint. In a review of the partial-range and full-range training studies, the strength gains showed up in the range that was actually trained, and testing outside that range showed less.
Wolf, Androulakis-Korakakis, Fisher, Schoenfeld & Steele, International Journal of Strength and Conditioning 2023
So if every rep you have done for ten years stopped short of the bottom, your bottom position never got a training stimulus. The range is available. The strength in it was never built, because nothing ever asked for it.
That is why a stretched range disappears within a week of not stretching. Nothing is defending it.
Fifty-five studies were pooled to ask whether lifting improves range of motion, and the answer was yes, by about as much as stretch training does. The reviewers drew a line under one detail: the gains came from the trials that used external load.
Alizadeh et al., Sports Medicine 2023;53(3):707–722 (55 studies)
An earlier review that put strength training head to head with stretching on range of motion found no difference between them.
Afonso et al., Healthcare 2021;9(4):427 (11 studies)
Then a controlled trial ran both for eight weeks and measured the second number as well as the first. Flexibility improved the same amount in both groups. Strength improved far more in the lifting group, and it improved at the far end of the range, not only in the easy middle.
Rosenfeldt, Stien, Behm, Sæterbakken & Andersen, BMC Sports Science, Medicine and Rehabilitation 2024;16:142
Same range. One group could produce force in it. That is the whole argument, and it is a narrow one. Loaded full-range work builds range and strength at the same time.
Three things decline in order as you get older. Power and strength go first. Muscle goes second. Cardiovascular capacity goes last. Flexibility is not a fourth item on that list.
Flexibility sits on the other side of the ledger. It is an outcome of the strength work, which is why we train it by loading the bottom of every movement instead of scheduling it separately. A deep squat that you own under a bar is a hip and ankle range you keep, because you built the force to defend it.
Getting into the range is the easy half to see. Producing force there is the half that decides whether you keep it, and you cannot judge that by watching someone move.
The whole gym runs on an AI-based strength measurement system. It reads every repetition you do, so we know what you produced at the bottom of the range and not just in the part that felt easy.
That is the reading that tells us whether the range you just gained is yours. The load goes where the force is missing, rep by rep. No junk reps.
Twenty-five minutes. No charge. You walk out with your numbers.
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