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Achilles tendinopathy treatment - understanding tendon capacity

Updated: Jun 2, 2022

If you’ve been following us for a while, you’ll know that we’re forever talking about the “capacity” of your Achilles tendon to cope with load and exercise. But what does capacity mean and why is it important to understand this concept/term when you’re recovering from Achilles tendonitis or tendinopathy?

Achilles tendinopathy treatment - why understanding tendon capacity is important.

Every part of your body (heart, lungs, muscles, tendons, bones etc.) has a certain capacity to cope or handle a certain amount of work/force/impact. I guess you could think about it as a measure of how “strong” that part of the body is. This capacity changes depending on what you do.

Maryke also discusses capacity in this video:

Exercise increases the capacity of your tendon to cope with load

When you run or jump, you develop micro-trauma in your Achilles tendon (and muscles etc.). This is normal. The body then uses the recovery period after exercise to replace the injured fibres with stronger ones. If you allow your tendon to recover fully between bouts of exercise, you’ll have a stronger tendon – you’ve now increased your tendon’s capacity to cope with the load from running and jumping.

Follow this link to find out how our online physio service for treating Achilles tendonitis/tendinopathy works.

Inactivity decreases your tendon’s capacity

If you have a long period of lazing around and not doing much exercise or you just have a break from running, the capacity of your muscles, tendons, bones etc. decreases. It’s literally a case of if you don’t use it, you slowly start to lose it.

This is why it’s important to ease back into running if you’ve not done it for a while.

Injury happens when you exceed your tendon’s capacity by too much

Achilles tendonitis or tendinopathy develops when you do exercise that exceeds the capacity of your Achilles tendon and do not give it enough time to repair itself. This causes the micro-trauma to accumulate, sending your tendon into disrepair.

Once injured, your Achilles tendon’s capacity to cope with work and load dramatically decreases. Before the injury you may have been able to run up hills, but once injured you may struggle to walk up a flight of stairs without aggravating your tendon pain.

Your Achilles tendon's capacity to cope with different training loads decreases dramatically when it's injured.

That’s why the first step in our treatment process is always to establish exactly what your Achilles tendon’s capacity is at this moment in time. We don’t just look at your ability to run, but also at all the other activities that load the Achilles, including things you do in your daily life and work.

I often see people mention on Facebook that they’ve tried strengthening their Achilles tendon, but that the exercises had made their pain worse. This usually happens when you are prescribed the wrong volume of exercise – that exceeds the capacity of your injured Achilles tendon.

There is no one-size-fits-all and you have to work out the total volume of load that the exercises + other activities in your life will place on your tendon. This then allows you to design a strength training programme that is at the right intensity for your injured tendon.

Let us know if you need any help with this. You can consult us via video call for a thorough review or your injury, general strength, current training and goals and a tailored treatment plan.

Best wishes


About the Author:

Maryke Louw is a chartered physiotherapist and holds an MSc in Sports Injury Management. You can follow her on LinkedIn, Facebook, Twitter or Instagram.


  1. Cook J, Docking S. “Rehabilitation will increase the ‘capacity’ of your …insert musculoskeletal tissue here….” Defining ‘tissue capacity’: a core concept for clinicians. British Journal of Sports Medicine 2015;49(23):1484-85. doi: 10.1136/bjsports-2015-094849

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