If you’re a climber or boulderer and you constantly find yourself asking questions such as “why do I keep injuring myself?” then this blog post is for you. This post is also perfect for you if you do any sport which involves intense activity in short bursts, especially those in which muscles are tensed to maximal contraction. That includes Brazilian jiu jitsu, judo, weightlifting and even yoga.

This is the first in a series of blog posts about understanding and preventing injuries in climbing. In it I’m going to delve into the cause of a majority of climbing injuries – isometric strains.

Which injuries are likely to be caused by isometric actions?

The types of injury most commonly affected by isometrics going wrong are:

  • Muscle strains or tears, including biceps brachii, finger flexors and rhomboids
  • Wrist joint, ligament or cartilage strains or tears
  • Lateral or medial epicondylitis (tennis and golfer’s elbow, respectively)
  • Rotator cuff strains or tears including PASTA lesions
  • Carpal (wrist) bone displacement
  • Finger pulley injuries
  • Rib strains and periosteal avulsions
  • Shoulder joint dislocations and subluxations (both glenohumeral and acromioclavicular)
  • Some less common shoulder issues including Hill-Sachs lesions, SLAP tears, ALPSA lesions, long head of biceps ruptures

From this list you can see that most upper body injuries which are not caused by direct trauma (you hitting something or something hitting you) have some isometric component. Tendinitis, tendinopathy and enthesopathy are more likely to be chronic issues, though they may be triggered by isometric strains.

So what is an isometric action?

An isometric muscle action is one in which a muscle or a group of muscles is activated without those muscles changing length. The simplest example is the ‘plank’ exercise in the image below. When you plank, your arm, leg, back and core muscles are tensed but they don’t change length.


The Plank

The Plank, an isometric exercise



Isometric actions are really useful. They allow us to:

  • Hold a static posture when lifting something heavy
  • Maintain body tension when climbing and bouldering
  • Actively hang on a straight arm when clipping or shaking out in climbing
  • Prepare for a serve or volley in tennis
  • Do pretty much everything involved in grappling sports like Brazilian jiu jitsu
  • Maintain stability while putting in golf
  • Perform both simple and complex yoga poses

An elegant example of this phenomenon, from 450 BC, is the throwing of a discus, in which the thrower contracts isometrically throughout his body to ready for the coordinated movement to follow. As you look at the discus thrower it’s difficult not to imagine the state of primed tension throughout his body (partly owing to the action of mirror neurons in your brain right now).

Discus thrower

Discus Thrower


So if it’s natural and normal, what’s wrong with isometric action?

Nothing at all, most of the time. The system works so well that many people will never experience an injury from an isometric action. Isometrics are even given as rehabilitation exercises after injury to prevent muscle loss due to inactivity when normal activity is too painful to carry out. Sometimes isometrics are also prescribed to rehabilitate tendinitis (aka tendinopathy) and muscle tears.

But imagine that you’re lifting a 25kg weight or holding your whole body weight while climbing and let’s think about the forces going through the muscles. These larger forces easily cause injury. So we need to think about what might be going on when we are using our bodies under maximal load.

What actually causes the injury during an isometric activity?

Even if an isometrically contracted muscle appears not to be moving, the forces exerted on muscles, joints and tendons are actually higher than in a normal concentric contraction such as bending your arm (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5746261/). This means that if an isometrically contracted muscle is suddenly loaded with more force, it is likely to experience a strain or a tear.

What is it about climbing in particular that causes isometric strains?

Climbing is a sport in which an extremely high level of maximal muscle contraction is used to hold onto bits of rock (or plastic if indoors). Because of the force of gravity – about 9.8 m/s2 – the effort to pull oneself upwards is pretty substantial. In our early climbing days our shoulders and arms feel like lead the day after a climb because we rely too much on upper body strength. As time goes on we learn to move in a more sophisticated way and we utilise our abdominal core and our legs, but as we progress and want to climb more difficult routes, this is where injury is more likely.

When a muscle is isometrically contracted in its most elongated position (a straight arm holding a very small hold), the force going through the muscle fibres is much greater than when the arm is bent. If your foot slips at this point, the resulting shockwave which goes through the muscle attachment points leads to tissue failure, and that equals injury. In the image below, the climber’s left arm is the one at risk of injury should she slip while pulling on this hold. The right arm, bent, is much less likely to experience injury.


Climber demonstrating isometric load (left arm)


A note on ‘Pump’

As a side note, this also explains why a locked off bent arm position is tiring and leads to the concept of ‘pump’, but does not usually cause injury. Muscle fibres which are not at their full length are just not so prone to injury. Furthermore, this is exactly why if you are asked to lift something heavy you will naturally bend your legs or your arms rather than attempt the task with straight limbs.

So how do I avoid isometric injury in climbing?

  • If you feel any pain when pulling yourself up through a difficult move on a straight arm, immediately stop, reset, and think if it could be done a different way. That pain, even if it doesn’t cause an injury, represents at least a strain of your muscle fibres and is likely to lead to relative weakness and continued pain over the following days.
  • If you feel yourself falling when climbing and it’s safe to fall, don’t just hold on with a straight arm as your only point of contact. This is a high percentage injury moment. Better to take the fall and try the move again.
  • Think about difficulty vs conditions when you climb on rock. Slippery routes are likely to cause isometric injuries because of the risk of unwanted body movement while you’re holding that tiny hold. Remember, what we are trying to avoid is sudden unwanted movement on a fully tensed isometrically contracted muscle.
  • Warm up properly. All injuries are less likely when your tissues are warm.

  • Take regular rest days to allow rebuilding of your connective tissues.

  • Use your interoception (the sense of how you are feeling in your body) to determine the right type of climbs for that day, even if they don’t fit your overall training goals. Don’t overstretch yourself and risk injury. If you’re feeling tired or under the weather, don’t push it so much.

  • Focus on the task at hand and try to minimise distraction. Your brain does its best to plan actions and does so best when you aren’t distracted or tired, which is another reason to climb according to how you’re feeling.

  • Get some coaching from a good instructor
  • Climb both on boulders and lead routes. Studies show increased finger strength from bouldering and better forearm endurance from lead climbing.

Thank you for reading. If you have questions or comments please email me via The Practice at 322. As well as running a general osteopathic practice, I am a climber and I also specialise in treating climbing injuries. I’m always happy to help with anything that might be bothering you.


Further related reading

I highly recommend the work of Dave Macleod, whose bibliography is available here: https://www.davemacleod.com

If you want a primer on muscle physiology, here’s a good one: https://www.clinicalkey.com/#!/content/book/3-s2.0-B9780323597128000060