Where isotonic exercises fit into Achilles rehab
- Maryke Louw
- 17 hours ago
- 7 min read
Isotonic calf raise exercises form an essential part of most Achilles injury rehab plans, because they closely mimic how you will be using your calf muscles and Achilles tendons once you get back to your normal activities. Learn the various ways of doing isotonic calf raises and why a "one size fits all" approach is not the way to go for your Achilles rehab.
Remember, if you need help with an Achilles injury, you're welcome to consult one of our team via video call.
The terms tendinitis, tendonitis, tendinosis, and tendinopathy mean the same thing for all practical purposes, and we use these interchangeably in most of our articles.
In this article:
What are isotonic Achilles exercises?
Isotonic exercises can be defined as any exercise that makes the muscle work through its full shortening (concentric) and lengthening (eccentric) cycle.
Let’s use the calf raise exercise as an example. As you lift up on your toes, the calf muscles shorten as they contract to lift your heel (concentric muscle contraction), and as you lower your heel down to the floor, the calf muscles lengthen while contracting to control the downward movement (eccentric muscle contraction).
👉 Isotonic calf raises are popular in Achilles rehab plans because they closely mimic the action of how our calf muscles and Achilles tendons work when we walk, run, or jump and have a proven track record in treating Achilles tendonitis. But, like with isometric and eccentric Achilles exercises, isotonic exercises must be adjusted to suit your specific case (tendon strength + sensitivity) to be effective.
So, let’s look at how you can adapt them.
The basic isotonic calf raise
One basic version of an isotonic calf raise is when you stand with equal weight on both legs, and slowly lift up onto tiptoes, pause for a moment, and then lower back down. If you perform it with straight knees, it targets the gastrocnemius muscle more and with bent knees, the soleus.
You can adapt isotonic calf raises in various ways:
Do them on double legs vs. single leg
Add weights
Change the speed of the movement during both lifting and lowering, or only during one part
Work into a stretched position (doing them over a step) vs. intentionally limiting the amount of stretch by doing calf raises to floor level or even wearing shoes with heels
Limit how high you lift.
What version should you do?
Isotonic calf raises are very versatile, and the benefits change depending on how you do them. So, the type or version of calf raise you do should match your current rehab goal. Your rehab goals will change as your injury recovers, so your exercises should also change as you progress.
It’s also important that your rehab exercises match your tendon’s current strength and sensitivity otherwise they can either make your symptoms worse or have no effect.
So let’s look at how you can adapt them depending on what is needed in different scenarios.
Sensitivity
If you currently have a very sensitive and painful Achilles tendon or are very worried that doing any exercises will make things worse, then we often find low-load calf raises, where you’re supported on both feet or sitting down, are the best option.
💡 Doing these low-load exercises daily can help to reduce pain, improve circulation, get you used to the calf raise action, and boost confidence to progress to more challenging versions.
But it might also be that we decide isometrics are a better option – there’s no recipe that always works for everyone – we decide what exercises on a per case basis. I share some options that work well for very painful Achilles tendons in this article.
Weights
If your physio determines that the main aim at the moment is to build more strength in your Achilles and calf, they may progress your plan to start using weights. If you’ve only been doing low-load exercises, they’ll slowly ease into things and build up to heavier weights over time.
If you’re pretty active already and your tendon can currently tolerate quite a lot of work (we determine this through our assessment), they might immediately prescribe a plan that includes single leg calf raises using heavy weights, performed 2 to 3 times a week — having recovery days between heavy strength training sessions are very important to avoid overloading the Achilles.
What weight is seen as “heavy” is different for every person and relative to their current strength as well as their own body weight. Your physio can help you understand how to decide what weight is right for you.
💡 To prevent Achilles injuries recurring, it’s important for the rehab plan to build the level of strength needed for the type and amount of activity you eventually want to do.
The ultimate strength training goal for a walker will look very different from that of a runner or triathlete for instance.
Speed
Your physio may get you to change the speed at which you perform the movements — lifting explosively but lowering very slowly to develop explosive power, or focusing on taking at least 3 seconds to lift and 3 seconds to lower to work on better overall control. If you do jumping or hopping sports, you’ll likely be given plyometric type isotonic exercises.
Working into stretch
When you lower your heel over the side of a step, the calf and Achilles tendon is stretched and the lower part of the tendon also compresses against the heel bone. If you have insertional Achilles tendonitis, this position can often irritate the injury — a bit like pressing on a bruise — in which case calf raises to floor level is the better option.
In contrast, midportion Achilles injuries often respond better to doing the calf raises over a step.
👉 If you want help with figuring out the best exercises and progressions for your specific case, this is exactly the sort of thing our team can assess and provide via Video Consultation. You can read more about how our online treatment process works here, or feel free to email me (Maryke) if you have any questions contact@treatmyachilles.com.
The rigid-programme trap
I often get emails from people asking whether our treatment programme is right for their specific case. Here’s the thing: Our team doesn't use any specific “plan” – there is no set programme! Instead, we use the research to guide our choices but assess each person’s case individually, and then design their plan for what they specifically need. And we update the plan as they recover and their situation changes.
A rehab plan should never be a rigid thing. Yes, for some people the type of exercise (isotonic vs. isometric vs. eccentric) might remain broadly the same throughout their recovery, with the only change being what weights they use. But often, the types of exercise will change and evolve as they progress depending on what we assess is the next element that needs to be addressed.
A person might start with isometrics to help settle their pain. They might then move on to low-load isotonic calf raises to help get them used to the movement and test their tendon’s tolerance to moving through the full range of movement.
They might move on to heavier loads and even include slow eccentric lowering exercises if they struggle to lift in certain parts of the range. If they’re a runner, we might add in plyometrics before easing them into running. Walkers can usually skip plyometrics and simply ease back into walking.
At the same time, we might include other exercises that strengthen the rest of the body. Or other types of cardio.
💡 The most important thing is that the plan must start at a level that the tendon can currently tolerate and slowly progress and rebuild tendon capacity to the level needed for that person’s goals. It must also be realistic and fit in with their life and other responsibilities.
👉 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
Where isotonic exercises fit into Achilles rehab (this article)
Eccentric exercises for Achilles tendonitis - How they work and when to use them
How we can help
Need help with your Achilles or related 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 or at least 10 years' experience in the field. All of us have a wealth of experience working with athletes across a broad variety of sports and ranging from recreationally active people to professional athletes. You can meet the team here.
About the Author
Maryke Louw is a chartered physiotherapist with more than 20 years' experience and a Master’s Degree in Sports Injury Management. Follow her on LinkedIn and ResearchGate.