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A2 Pulley Injuries in Rock Climbing

Updated: Jun 15, 2020

There’s a project you’ve been working on with strenuous crimpy moves. You’ve been climbing pretty aggressively for the past 3–4 weeks not allowing your hands to recover. You crimp down, sink the weight into your fingers and all of a sudden you hear and feel a big “POP”. The adrenaline rushes and initially you don’t really feel anything in your finger. But a soreness begins to creep in at the base of that finger. Squeezing it hurts. There’s a constant throbbing sensation. It’s starting to swell. Clearly something’s not right. What could it be? Most likely with the symptoms and mechanism of injury listed above, you may have injured one of your flexor pulleys. In order to know for certain refer to this post on how finger injuries are tested: Common Finger Injuries from Rock Climbing

The A2 pulley is stressed up to 3–4 times the amount of load applied compared to the fingertip

This post will be focusing on flexor tendon pulley injuries. How does it happen? Why is it the most common injury to climbing? How long will it be before you can climb again? Can you keep climbing? How are you unknowingly contributing to this injury? What can be done to prevent it?



Annular Pulleys

The fingers have 5 annular ligaments (A1–5) and 4 cruciate ligaments (C1–4) that hold the flexor tendons tightly close to the bones. This helps to give the finger maximum leverage and strength. When the muscles in the forearm are flexed the annular pulleys holds the rope like tendon in place and curls the finger in.

Location of A1-A5 pulleys. From Neumann DA. Kinesiology of the Musculoskeletal System.St. Louis: Mosby, 2002.

Injury to these pulleys occur when the load applied to the system is far too great for the pulleys to bear. Failure occurs and the pulley is partially torn or there is a complete rupture. A complete rupture of the A2 and A3 pulley will result in a bowstringing of the tendon as depicted in the figure below. In some cases the A4 pulley will also blow out.


Injury to the A2 flexor pulley. From Neumann DA. Kinesiology of the Musculoskeletal System. St.Louis: Mosby, 2002.

With a complete rupture of only the A2 pulley, the tendon popping up against the skin can be very subtle.

If that finger is opposed with the thumb like when pinching, you might be able to feel a greater separation of the tendon to the bone. Compare right to left. The Bowstringing will be more apparent if more than one pulley is ruptured. Still with good history taking and a thorough clinical examination, a good clinician should be able to diagnose a flexor pulley injury.

A2 Pulley

The most common pulley that gets injured is the A2 pulley. This happens because of the immense pressure with the closed hand crimp position in climbing. In this position, the second joint from the fingertip is flexed past 90 degrees and the first joint from the fingertip is hyper extended. This causes the flexor tendons to apply the greatest amount of stress on the A2 pulley, up to 3–4 times the amount of load applied compared to the fingertip. A simple slip of the foot or dynamically loading that hand in attempts to make the next move in your climb can cause a dramatic increase in stress and possibly failure of the A2 pulley.

Why is the ring finger the most common victim?

Schöffl explains the mechanism of injury well in his article, Injuries to the Finger Flexor Pulley System, The Journal of Hand Surgery / Vol. 31A №4 April 2006. He explains when you are in the closed hand crimp position, your wrist slightly supinates (motion of turning your thumbs up) and side bends towards the pinky finger. This angle places greater stress on the ring finger. The middle finger is protected on both sides by fingers of about the same length. The index fingers is supported by the middle finger and the strong thumb. The ring finger has the middle finger to support it on one side, but only has the short pinky finger to support it on the other side. Thus the ring finger is more prone to injury.

Single pulley ruptures are generally treated non surgically

Surgery? The standard procedure for a single pulley rupture is to treat the injury conservatively. Getting physical therapy for about 4–6 weeks will significantly help to reduce the risk of re injury and you will learn what is safe and what is dangerous to perform in the early stages of healing. But when there is more than one pulley blown out, the chances of surgery goes up. Look at the chart below.

How long will it be before you can climb again? That depends on how severe your pulley injury is. Below shows a general guideline on how to go about measuring your return to climb. But if you heard and felt a pop, you should still go see a doctor. Don’t self diagnose by reading what google says.

Strength deficits from the injured finger to the non injured side disappears after 3–6 months

How long will it be until my strength comes back? The good news is that your strength will come back. Single A2 pulley ruptures, If treated non surgically, you should still be able to return to full climbing. The idea that climbers will not be able to return to full climbing if not surgically corrected is a false notion. A Study that Schoffl conducted showed that strength measurements demonstrated no significant deficits in the injured finger. (SCHOFFL V. R., F. EINWAG, W. STRECKER, and I. SCHO¨FFL. Strength Measurement and Clinical Outcome after Pulley Ruptures in Climbers. Med. Sci. Sports Exerc.,Vol. 38, №4, pp. 637–643, 2006) However, the relatively bad news is that it will take a long time. Strength deficits from the injured finger to the non injured side disappears after 3–6 months. And almost completely after one year. (Schoffl V, Hochholzer T, Winkelmann HP, Strecker W. Pulley injuries in rock climbers. Wilderness Environ Med 2003;14:94–100.) Does this mean you won’t be able to climb for 3–6 months? Absolutely NOT. It means you probably shouldn’t be climbing very aggressively until your fingers feel equal in strength. Less water equals less elasticity which means more rigid tissues and maybe… pop!

Why did this happen to me??? It depends on a combination of multiple factors such as how aggressive are you? The more aggressive, the more risk. If you’re throwing for every hold and cutting feet, the wear and tear of your fingers will happen a lot faster. On a similar note, how smooth and precise are you? Some people climb almost like it’s a dance. they flow from one hold to the next like water. Their foot placement is on point and glued to that rock momentarily. It’s almost like every climb is an expression of art. With the transfer of weight from limb to limb and using your entire body to climb, this decreases the stress on just your fingers.

Repetitive stress diminishes tissue integrity

How long have you been climbing?

If you’ve been climbing for less than a year, your fingers have yet to adapt to the weight of your body hanging on them. Although your muscles are getting stronger, ligaments and tendons (there are no muscles in your fingers!) need more time to reinforce itself.

How monotonous are your climbing sessions?

If you get stuck doing the same climb over again, you are repeatedly stressing vulnerable areas multiple times over. There is no time for those tissues to recover. The same thing happens when you attempt that single crux several times. Repetitive stress diminishes tissue integrity.

If you’ve been climbing for less than a year, your fingers have yet to adapt to the weight of your body hanging on them.

How often do you train?

Not giving yourself ample recovery time makes your fingers more susceptible to injury.

How much water do you drink?

Your body’s elastic properties have a lot to do with how hydrated you are. Less water equals less elasticity which means more rigid tissues and maybe… pop! And sometimes freak accidents are inevitable. But by following some of these basic guidelines below we want to lower the chances of freak accidents.



Here are some easy guidelines to follow and lower the risk of rupturing a pulley. Always practice safe climbing!

Open Hand Crimp Crimping with an open hand will decrease the stress in your fingers and distribute the force evenly. Closed hand crimping is not wrong. There are times when that’s the only way you can grab the rock. Howeverl ike we already described above, with a closed hand crimp you are just putting more stress on the A2 pulleys. Practicing to climb with better technique will prevent a lot of injuries. It may feel awkward at first and you may not trust the open hand crimp, but keep practicing and it will help you in the long run.

Don’t let your ego get the better of you

2–3 attempts and STOP

When you come to that crux move and it doesn’t go after 2–3 attempts, just stop. Don’t let your ego get the better of you, it’s not worth all the pressure on your fingers. Save the problem for another day after the stress is resolved. Come back to it when your fingers are rested.


(This section has been updated on 4.13.2018)

The research does not look too favorably on taping. It has shown that taping will only decrease the amount of bowstringing of the flexor tendon by no more than about 5%. And taping around the A2 pulley may absorb only about a 10% of the force that is being applied to the A2 pulley. This does not result in a very effective injury prevention method. Protective pulley taping will be minimally effective in preventing a full pulley tendon rupture. However if taping is to be done, it’s more effective to tape closer to the distal end of the proximal phalanx!

Taping generally gives climbers a greater boost of confidence when making crux moves. So if the research states that taping won’t do much to prevent a pulley rupture and yet you’re mentally feeling stronger to make the move, it begs the question of how much more force are you really applying to your pulleys just by taping? There’s no easy answer. I rarely use tape myself. Now a days I’ll only use it if my fingers are too raw to even grab onto jug holds because I’ve been training too hard and there’s no more skin left. But those days are very rare…

With that being said, if that edge is so thin that the closed hand crimp is the only method that works, then make sure you reinforce that finger and tape it up before attempting it again.

Taping to support the A2 Pulley

You want to tape it loose enough where you don’t start to lose circulation but tight enough it will actually provide support to your pulleys. The tighter the better. It’s good to keep it tight, attempt the climb and take off the tape right away if you think it’s too tight. Keep practicing and it will get easier to tape. Be on the lookout for a separate post on how to tape!

Being a weekend warrior is one of the best ways of getting injured

Consistency Being a weekend warrior is one of the best ways of getting injured. If you’re only able to climb once a week, make sure you climb very easy routes for the first 30 mins of your climb to allow your tissues to adapt. And then for the remainder of your climb, 80% of it should still be at an easy to medium level difficulty. If you’re climbing pretty regularly, most of your climbs should still be between easy to medium level. The consistency of climbing at this easy going pace will help promote good adaptation to your fingers. Injuries occurs when there is failed adaptation. Failed adaptation happens when you are climbing too hard too fast too much.

For example, if your hardest redpoint climb on top rope is a 5.10, then you should be consistently climbing multiple 5.8 routes and a couple 5.9 route in order to condition your body. The next time you attempt another 5.10 route, it’ll be a piece of cake for your fingers to handle the stress. This is a simple example of how to properly condition your body. We only see the amazing climbs the pros redpoint. But it takes a lot of consistent training to get there.

your urine should be clear or have just a hint of yellow

Drink Water If at any point you go to the bathroom and your urine is yellow, you are not drinking enough water. Besides people who take a lot of supplements (bright yellow urine), your urine should be clear or have just a hint of yellow. otherwise you are not supplying your body with the water it needs. Try to break a dried up sponge. And then try to break a sponge full of water. You want to be that sponge full of water!

Collagen turnover rate in your body is 300 days. So it will take up to a year for those pulleys to bulk up and keep you safe

Take Vitamin C

Without having to get too technical, collagen is the essential matter that makes up the pulleys in your fingers as well as all other tissues such as muscles, tendons, ligaments, etc. Collagen is designed to resist tensile loads. Vitamin C play a very essential role in helping to keep the collagen fibers in your pulleys well lubricated and also will help to formulate new collagen fibers to reinforce your pulleys and make them stronger. But don’t expect this to happen overnight. Collagen turnover rate in your body is 300 days. So it will take up to a year for those pulleys to bulk up and keep you safe.


Suspect a pulley Injury?

Apart from that horrible snapping sound you never want to hear or feel when you’re crimping down, there might be other clues as to whether your pulleys are strained. Below are a couple methods that may help.

Tenderness Squeeze the base of your finger and compare right to left. If it hurts, there’s a good chance your A2 pulley is being overly stressed and cannot tolerate the climbs you are putting it through. Do lighter climbs for 2 weeks until there is no more pain with palpation. Or take a couple days off to give your hands rest. Obviously you can apply the same method for feeling the A1 to A5 pulleys.

Swelling With A2 pulley strains, there might be swelling around the base of your finger. You find it very common for there to be swelling for ligament tears. Compare right to left, if there is swelling, take it easy for 2 weeks, climb easier routes, tape you finger up, work on your technique and footwork to give your hands a break.

Stay off of crimpy routes If you are suspecting a strain of your A2 pulley, then it’s best if you hold off on all crimpy routes for 2 weeks. Get on jugs, slopers, pinches… anything but crimps! No other grip will stress your A2 pulley like that closed hand crimp. There are plenty of climbs out there you can work on. In fact you probably should work on slopey pinchy routes because those are everyone’s weakness.


Videos of Popping Pulleys:

Now for the fun stuff. I have gathered several videos where people have ruptured a pulley and it makes your spine tingle. I hope this never happens to you. practice safe climbing at all times!



All content within this column is provided for general information only, and should not be treated as a substitute for the medical advice of your own doctor or any other health care professional. Lee Physical Therapy is not responsible or liable for any diagnosis made by a user based on the content of this site.


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