Isometric exercises for Achilles tendon injuries – How, when, & pitfalls
- Alison Gould
- 17 hours ago
- 10 min read
Isometric exercises for Achilles injuries (whether it's Achilles tendonitis or tendon tears) are useful only in some cases. We demonstrate variations on isometric calf raises and provide guidelines on when and how they would be appropriate for Achilles injury rehab.
The terms tendinitis, tendonitis, tendinosis, and tendinopathy mean the same thing for all practical purposes, and we use these interchangeably in our articles.
In this article:
My colleague Maryke also discusses isometric exercises in this video:
What are isometric Achilles exercises?
Isometric exercises involve a hold or a static contraction (no movement). As you’re reading this, tense your buttocks as hard as you can – this is an isometric contraction. Your muscles contract, but your body does not move.
For the Achilles tendon and calf muscles, an isometric exercise would involve rising up onto your toes and then holding that position. There are many variations that can be used in Achilles rehab, and not everyone needs these exercises – more on this later.
Let’s take a look at the different ways you can do isometrics and to whom they might apply.
👉 Please remember that every person is different and that exercises must be adjusted to suit your specific case (tendon strength + sensitivity) to be effective.
How high should you lift when doing isometric Achilles calf raises?
This is one of the most common questions we get.
The answer depends on what type of Achilles injury you have, what feels comfortable for your Achilles, and what your rehab goal is when doing the isometrics.
Maryke demonstrates the various isometric calf raises:
Neutral lift isometrics
This is when you stand on a step (or something like a thick book) with only the balls of your feet supported. Your heels are suspended over the edge, and you maintain them level with the height of the step – so they’re not hanging down over the edge or raised up.
✅ This can be a particularly useful position if you struggle with pain in the front of your feet (e.g. if you also have metatarsalgia or a neuroma).
❌ It can sometimes irritate insertional Achilles tendonitis or if you have heel bursitis – but this varies between people, so test it and see how your symptoms react in the 24 hours after the exercise session. If it does irritate your injury, doing a lifted version, reducing the load (see below), or switching to isotonic exercises (where you continuously lift up and down) might be a better option.
Heel raised isometrics
This is when you stand on the floor or a step and lift your heels a bit higher, but not as high as you possibly can.
✅ If you’re doing isometrics for pain relief, you can test which range feels most comfortable for you and use that. There is no “ideal” height for Achilles pain relief – it really just depends on what feels best for you.
✅ If you’re doing them to strengthen your Achilles tendon, your physio might ask you to hold the position at very specific heights, depending on which part of your movement lacks the most strength or where they feel it will provide the most benefit.
❌ In most cases – especially if you have Achilles tendonitis or bursitis – it’s not useful to try to do isometric calf raises in a fully lifted tiptoe position (forcing the extreme range), as this often causes a painful pinching sensation. Also, very few people actually need that extreme lift – dancers might be the only exception.
Heel drop isometrics
These are done by standing on a step (or thick book) and allowing your heels to drop over the edge. You usually lower them to around 10 degrees of dorsiflexion – so, not as low as you can go – and then actively contract your calf muscles to maintain that position. Don’t just hang passively; that isn’t an isometric heel drop – it’s just a passive stretch.
✅ Isometric heel drops can be classed as active stretches that can cause permanent lengthening of soft tissue over time and can be useful if you’re trying to improve calf, Achilles, and ankle range of motion. This can be useful in the later stages – only after 12 weeks – of rehab after Achilles tendon rupture repair surgery.
❌ This is not a typical exercise we would prescribe for any type of Achilles tendonitis and will likely make your symptoms worse if you have insertional Achilles tendonitis, heel bursitis, or if your tendon is simply not happy being stretched for long periods at this point in time. The stiffness you experience when you have these types of injury is not something that can be stretched out – it is caused by swelling in the tissue and requires other types of treatment.
🚨 Do not use heel drop isometrics for Achilles tendonitis or tendinopathy without speaking to your physio – in most cases they usually just irritate the tendon and make things worse.
How many, how often, and what weight to use?
The original research (done on patellar tendons) that suggested that isometrics might provide immediate pain relief for tendinopathy used very heavy weights and involved 5 repetitions of 45 seconds (with 2 minutes’ rest between reps) in a single session.
👉 However, this protocol has so far not been found to be useful or effective in Achilles rehab research. There is also no research that has specifically looked at the best isometric programmes for strengthening tendons.
In practice, we find that – as with all rehab exercises – isometric Achilles exercises should be adapted to suit the individual and are really only useful in very specific cases. We also teach our patients to monitor their response to exercises and give feedback so we can adapt their plans and make sure it fits them well.
Here are some of the ways we use when adapting isometrics.
Weight
We find that people with very sensitive tendons that flare up easily, or who might not be very strong, tend to do better with lower loads – for example, doing isometrics supported on both legs and without any added weight.
More active individuals, whose tendon injuries are less easily irritated, might be able to do them supported on just one leg and with a significant amount of added weight.
Repetitions
In cases where someone has a tendon that flares up easily or they are nervous about starting exercises, we usually begin with around 3 repetitions. In less irritable cases, we might start straight away with 5.
Hold times
Short holds (around 10 seconds) is usually a good starting point for easily irritated tendons or for people who are not very strong – this should then be progressed over time. Stronger or less irritable tendons are often happy to start with 30–45 second holds.
Rest time between repetitions
The longer you hold the contraction and the heavier the load, the more recovery time you should allow.
If you’re only doing 10-second holds on two legs without any added weight, you might need just 10–20 seconds of rest.
If, on the other hand, you’re lifting the maximum weight you can tolerate and holding it for 30–45 seconds at a time, you’ll likely do better with around 2 minutes of recovery between repetitions.
Frequency
In most cases, isometrics can be performed daily, although there are, of course, exceptions.
👉 Your physio might prescribe a very different set of isometric exercises for you – the options listed above are just some of the most common ones we use.
What are the proven benefits of isometric Achilles tendon exercises?
Isometric exercises are often included in tendon rehab because they are thought to:
Help reduce tendon pain.
Help strengthen the injured tendon.
Help reduce pain while maintaining muscle and tendon strength when you’re in a competition phase and want to avoid the muscle soreness and/or exercise-related tissue damage caused by other types of strength training.
Help improve calf and Achilles length or flexibility.
🤷♀️ But do they actually work? What does the research tell us?
Can isometric exercises reduce Achilles tendon pain?
Short answer: Isometrics can contribute to your overall recovery, but they are unlikely to provide immediate pain relief.
Why we say this:
There is a piece of research that got everyone thinking, as it appeared to show that doing isometric exercises for the muscles related to a tendinopathy could cause immediate pain relief. This research was carried out on the knee, specifically for patellar tendinopathy.
More recently, researchers have tried (and failed) to replicate these findings when looking at isometrics for pain relief in a variety of tendon problems across the body, including the Achilles. The results of these studies showed that isometric exercises are no better than exercises with movement (isotonics) for immediate pain relief in tendinopathy. While they helped some patients, they had no effect for others, and in some cases even increased pain immediately after the session.
The key thing to remember is that Achilles tendinopathy or tendonitis is a longstanding condition that takes several months to resolve and usually requires a combination of treatment factors – not just a specific exercise. For Achilles tendinopathy, rehab success should not be measured by immediate pain reduction – that comes with time and perseverance.
👉 That said, this doesn’t mean that isometrics are useless when it comes to injury rehab. They can contribute to your gradual overall improvement – regardless of the type of Achilles injury you have – if used appropriately. More on this later.
Can isometrics help to strengthen your tendon?
Yes, there is evidence that isometric exercises, when used as part of a tendinopathy rehab plan, can improve the injured tendon's ability to carry load.
Are isometrics useful during a competition phase?
We’ve already seen that the research shows inconsistent results when it comes to pain reduction. But should we be adding isometrics at this point to maintain strength?
Short answer: You will likely benefit more from adjusting your general training than from adding isometrics.
Here’s why we say that:
The challenge during your competition phase – the final build-up to an important race or a run of key matches – is that you can’t really take time off to focus on rehab. Achilles tendonitis is an overuse injury, so recovery requires reducing tendon load and then rebuilding it gradually. In our experience, adding extra load through rehab exercises on top of full training is usually not the right approach.
Yes, we've seen earlier that isometrics can strengthen your tendon. However, simply doing your sport already strengthens your tendon. So, if you’re currently in a competition phase, you don’t necessarily need to add extra exercises on top of your training to maintain strength – finding ways to allow better recovery is usually more effective.
👉 Some of the things we might suggest include increasing recovery time after hard training sessions, switching up the terrain you train on, or replacing some training sessions with cross-training activities that are less demanding on the Achilles.
That said, some patients do find that isometrics help reduce their pain. In those cases, they can be a useful adjunct to regular training during this phase, but you usually still have to adjust the overall training volume or structure.
Can isometrics improve calf and Achilles length or flexibility
Yes, there is evidence that isometric exercises performed in a position where a muscle is lengthened (like with your heel dropped over the side of a step) can cause permanent lengthening of muscle cells over time.
It is not yet clear from the research if isometrics has any permanent effect on the tendon length itself.
When we use isometric exercises for Achilles injuries
The key to a successful rehab plan is to start your exercises at a level that’s right for you, and then progress them by making them more challenging over weeks to months as your tendon’s symptoms improve and function returns.
When we assess an Achilles injury, we look at your tendon’s capacity – in other words, what activities you can do and what they feel like when you do them. We all have different starting points because of our tendon’s current level of injury, our fitness levels, other health issues, and our goals and aspirations.
✅ For strength training, we view isometric exercises as the right starting point for you (regardless of the type of Achilles injury) if:
You find isometric exercises challenging.
They cause no more than an acceptable level of pain.
You can’t yet progress to more challenging exercises (such as isotonic exercises).
Or you can’t do calf raises where you lift up onto your toes because of a different injury affecting the front of your foot.
👎 If isometric exercises are too easy and you’re able to do more challenging movements, you don’t need to start here and will likely benefit more from other exercises.
As you grow stronger and your tendon regains strength, the isometric exercises should also be progressed to become more challenging (examples discussed earlier).
We might also include them as active stretches later in tendon surgery rehab plans ✅, but we don't use them as stretches when someone has tendonitis or bursitis ❌
👉 We have detailed discussion about exercise-based treatment plans for Achilles tendonitis here and for Achilles tendon tears.
Other articles in the Achilles tendinopathy exercise series:
Progressive treatment exercises for Achilles tendonitis/tendinopathy: What, when, and how much?
Is stretching a good idea with an Achilles tendinopathy/tendonitis?
Isometric exercises for Achilles tendon injuries – how, when & pitfalls
Isotonic exercises - What they are and how to use them for treating Achilles tendonitis
Eccentric exercises for Achilles tendonitis - How they work and when to use them
How we can help
Need help with your Achilles injury? You’re welcome to consult one of the team at TMA online via video call for an assessment of your injury and a tailored treatment plan.
We're all UK Chartered Physiotherapists with Master’s Degrees related to Sports & Exercise Medicine. But at Treat My Achilles we don't just value qualifications; all of us also have a wealth of experience working with athletes across a broad variety of sports, ranging from recreationally active people to professional athletes. You can meet the team here.
About the Author
Alison Gould is a chartered physiotherapist and holds an MSc in Sports and Exercise Medicine. You can follow her on LinkedIn, Facebook, Instagram, and Twitter.
References
Gravare Silbernagel K, Vicenzino BT, Rathleff MS, et al. Isometric exercise for acute pain relief: is it relevant in tendinopathy management? British Journal of Sports Medicine 2019;53:1330-1331.
Van der Vlist, A. C., van Veldhoven, P. L., van Oosterom, R. F., Verhaar, J. A., & de Vos, R. J. (2020). Isometric exercises do not provide immediate pain relief in Achilles tendinopathy: A quasi‐randomized clinical trial. Scandinavian Journal of Medicine & Science in Sports, 30(9), 1712-1721.
Bradford, Ben, Ebonie Rio, Myles Murphy, Jacob Wells, Mizanur Khondoker, Celia Clarke, York Chan, and Rachel Chester. "Immediate effects of two isometric calf muscle exercises on mid-portion achilles tendon pain." International Journal of Sports Medicine 42, no. 12 (2021): 1122-1127.
Akagi, R., Hinks, A., & Power, G. A. (2020). Differential changes in muscle architecture and neuromuscular fatigability induced by isometric resistance training at short and long muscle-tendon unit lengths. Journal of Applied Physiology, 129(1), 173-184.