Learn pocket holds in bouldering: grip two- and three-finger pockets cleanly, build up mono pockets in doses and protect your hand from tendon and muscle tears.
A pocket (German: Lochgriff or Fingerloch) is a small hold that looks like a hole and that you can hold with one or two fingers [1]. The honest answer to "Isn't that just a small hold?": no. Here your body weight hangs on one, two or three fingers, and that is plain arithmetic: the fewer fingers, the more load per finger.
The same is true on the injury side. In a one-finger pocket the finger joints stand at roughly 20–40° of flexion and the neighboring fingers are flexed almost fully, which triggers the so-called quadriga effect [2]. If you hold the pocket with the ring or little finger, the deep flexor tendons shift and a hand muscle, the lumbrical, can tear [2]. In a cadaver model, the connection at the little finger tore at a mean load of 11 kilograms, roughly a full ten-liter bucket of water [3]. That was a lab test, not a climber, but it shows the direction. In the open-hand grip you flex the middle finger joint only about 39° on average, in the crimp about 87° [6]. So the hand stays much more open, but the load is spread over fewer fingers once the pocket is small.
Expect to grip two- and three-finger pockets cleanly after a few sessions. Mono pockets take much longer to build up, in months (an experience value, not a measurement).
Entry criteria (practice standard):
Check how many fingers fit, how deep the pocket is and in which direction you can pull. Biomechanics lists deep and flat two-finger pockets among the open and half-open hand grips [5]. You do not need to squeeze the fingers in.
Milestone: For every pocket on the wall you can say how many fingers fit.
Place index, middle and ring finger and unload the pocket with your feet. Grip loosely, because biomechanics calls it "soft gripping": grip force should not be higher than necessary [5].
Milestone: You hang three times for five seconds with foot support and no pain.
Use index and middle finger or middle and ring finger and make sure the wrist stays straight. The joints stay in an open posture.
Milestone: You hold a two-finger pocket three times for three seconds and continue under control.
Pockets are not long-hang holds. Let the legs pull, set the hand briefly and unload as soon as the next hold is secure. The load on the pocket stays short.
Milestone: You climb a boulder with two pockets without hanging on one for longer than three seconds.
The one-finger pocket is the territory of the case series. Use the middle finger, not the ring or little finger [2], and keep it short and low. Build up over weeks to months and get out at the first pain.
Milestone: You hold a mono pocket with the middle finger under foot support twice for three seconds and feel no pain.
I found no study that measures injury risk per move on a pocket. What exists: a case series of 60 patients with a lumbrical tear, 57 of them climbers, with three grades (grade I: 18, grade II: 32, grade III: 10). All recovered and returned to climbing, grade III healed noticeably longer [4]. Such studies say nothing about risk per move, only about what injured people experience. Warning signs are pain in the palm or at the base of the finger; stop at once and have it checked by a doctor. Build up pockets over weeks and start with three- and two-finger pockets. This guide explains and motivates but does not replace supervised training or medical advice.
Do the open-hand check: when you grip the pocket, the hand should stay open and not cramp. Ask yourself: could I still move my thumb a little? If not, you are gripping too hard. This is practical experience and not proven.
A pocket or finger hole is a small hold that looks like a hole and is held with one or two fingers [1]. There are one-, two- and three-finger pockets; the fewer fingers fit, the more load lies on each finger.
Usually index and middle finger or middle and ring finger. In a one-finger pocket the middle finger is the better choice, because pockets held with the ring or little finger are described as a risk for the lumbrical muscle [2].
Pain in the palm can be a sign of a lumbrical tear, which has been described after pockets held with the ring or little finger [2][4]. Stop and have it checked. Most patients in a case series recovered fully [4].
They are demanding, but doable with a build-up. No study measures the risk per move. The case series show muscle and tendon injuries, mostly in the mono pocket [2][3]. Build up over weeks and start with more fingers in the pocket.
Kneebar: Resting With Your Thigh