Stand at the base of any bouldering wall for ten minutes and count the grips. On the warm-ups, open hands and lazy half crimps. On the hard moves, knuckles stack up and thumbs come over. Full crimp is what most climbers reach for the moment a hold gets small and a move gets desperate.
Now go and read the training plan those same climbers follow. Half crimp on a 20mm edge, maybe an open-hand day, maybe some three-finger drag work. The grip they use on every hard move they've never once loaded on purpose.
The taboo is not stupid
There is a real reason full crimp got the reputation. In a full crimp, knuckles high and the fingertip joint slightly hyperextended, the force through the A2 pulley can reach several times bodyweight, and modelling work shows the middle and ring fingers carrying consistently higher pulley load than the index or little finger. The ring finger is the most common site of an A2 rupture. Our pulley post covers that mechanism, the survey data behind it, and the extensor gap that sits underneath it. None of that is in dispute here, and none of it is repeated here.
What the taboo gets wrong is the conclusion. "Full crimp is dangerous, so exclude it from training" leaves the position in your climbing and removes it from the only place you control the load.
The reframe: where you build it, not whether you use it
This is a general principle before it is a full-crimp one, and it is worth stating in the general form: the moment you need a hard position is not the moment to develop it. That applies to a drag on a rounded hold, to a back-three pocket, to a comeback after time off, and to anything else your hands are going to be asked to do badly under pressure. Full crimp is just where it bites hardest.
Think about when your fingers actually meet a hard full crimp. It is move six of a project attempt. The edge is whatever the rock decided. The load is whatever the move demands. Your fingers are on their fourth session of the week and the last twenty minutes were spent falling off the same move. You didn't choose the depth, the weight, the angle, or the day.
That's not training the grip. That's finding out about it.
The alternative is dull by comparison, which is the point. You pick the edge. You pick the load. You pick a day when your fingers are fresh, which for max-intent work means before you climb or on its own day, per our session order post. Then the full crimp you hit on rock spends capacity you already built instead of trying to manufacture it under duress.
Who this is not for
Loading a position deliberately only helps if there is something underneath it to load. The people who should leave this alone for now:
Tendons do not like surprises. A new grip position is a surprise.
- Anyone without a half-crimp base. Half crimp is the base position and the test position for good reasons, and if you haven't built a year or so of consistent, progressive loading in it, adding your most demanding grip on top is stacking intensity on nothing. Start with a structured base like our 8-week no-hang program.
- Anyone newer to finger training than the tissue timeline allows. Tendon, pulley, and bone adaptation runs on a clock measured in months and years, not weeks. Our timelines post lays out why your nervous system can drive your fingers harder than your pulleys are ready for, which is exactly the failure this whole idea is trying to avoid. See also the V4 rule post for the beginner version of the question.
- Anyone with a tender A2, a recent tweak, or pain the day after a session. That is a reason to get assessed, not a reason to add load in the position that stresses it most.
The dose, and it is smaller than you expect
Here is what we actually do, and it's deliberately unglamorous.
That is the whole prescription. Not a session, not a block of sets, not a percentage scheme. A handful of near-maximal singles in the position, once, and then you leave it alone and go do your half-crimp work.
Two things about that are worth dwelling on. The first is how little of it there is. Full crimp produces the highest pulley forces of anything your fingers do, and the honest way to train the highest-stress position is at the lowest possible frequency and volume that still asks for an adaptation. Heavy and rare beats moderate and often here, and it is not close.
The second is who it is for. This assumes a climber with a solid half crimp and years of load history behind them. If the previous section applied to you, this dose is not a smaller version of something you can start now. It's a thing you get to later.
What we're not going to print is everything past that. No set counts beyond "a few", no percentages, no eight-week progression. Those would be inventions, and a prescription that specific should come from someone's actual coaching practice or from a study. Plenty of places on the internet will hand you the full scheme. Take the ones that tell you where the numbers came from.
Where the work sits in a week
The dose above answers how much. This answers where, which is a structural question and matters just as much:
- Alongside half crimp, never instead of it. Half crimp stays the base and the number you track. Full-crimp work is an accessory, in the same sense our weird-grip post treats rolling edges and claws: a second, lighter exposure, not a second max day.
- A minority of your finger volume. If most of your loading is happening in the grip with the highest pulley forces, you have swapped one imbalance for another.
- Fresh, and progressed slowly. Frequency follows load, which our frequency post covers. Heavier work needs more room around it, and this is the heaviest thing your fingers do.
- Logged separately. A full-crimp number and a half-crimp number are different tests. Keep them in different columns or you will confuse a position change for progress. Our testing post covers why position consistency decides whether a number means anything.
What this does not buy you
Training the position on purpose does not make the position safe. It makes your tissue better prepared for a load it was going to meet anyway. Climbers who train crimp, half crimp, and open hand tend to stay healthier than climbers who only train the one they reach for when a move gets hard, but there is no clean trial proving it and we're not going to pretend otherwise.
There is one piece of evidence pointing the same way, and it is worth being precise about what it is. An ultrasound study of uninjured recreational climbers found that the people producing the highest fingertip forces had measurably thicker A2 and A4 pulleys, and that measurements above the usual 2mm threshold for calling a pulley injured turned up in plenty of hands with nothing wrong with them. That is consistent with pulleys adapting to load rather than only being damaged by it. It is also cross-sectional, which means it cannot tell you whether the loading built the tissue or the tissue permitted the loading. Direction, not proof, and we would rather hand you the caveat than the headline.
It also does not mean more full crimping on the wall. If anything, the argument runs the other way: build the position deliberately, off the wall, and you can afford to be more relaxed about how often you go to it while projecting.
The honest close
Full crimp is not a moral failing and it is not free. It is the position with the highest pulley forces in climbing, which makes it the position most worth preparing and the one least forgiving of being discovered mid-move. If you have the base, load it deliberately, in small amounts, on your terms. If you don't have the base yet, build that first, and keep full crimping on the wall exactly as much as you already do while you wait.