Treating tendinopathy: A clinical framework: part 2
Rehab Progressions
Research papers and protocols for tendon rehab often show a general progression starting with isometrics in the first phase then progressing to isotonics, plyometrics, return to running, and eventual return to sport. I think it's helpful not to think of these early phases as mutually exclusive. Often you can have a patient perform isometrics and isotonics concurrently, without necessarily performing isometrics in isolation. I try to follow in one of my co-workers, Dan Pope at FitnessPainFree’s shoes: have the patient perform the hardest variation of something they can safely perform and progress from there. With all of that as background, I will lay out a general framework for exercise progressions for patients with tendon pain.
Stage 1: Isometrics
As I said in the previous paragraph, very rarely do I start with isometrics in isolation and have no other exercises coincide with them. If the specific tendon of concern is not tolerating isotonics, we can generally train joints above and below without much pushback. But for our purposes let’s focus on isometrics. There are two distinct protocols, and they serve different purposes:
Long-duration, low-intensity isometrics (classic protocol: 5 sets × 30–45 seconds) The proposed mechanism here is analgesic. Rio et al.(7) showed that this protocol reduced cortical inhibition and increased maximal voluntary contraction by approximately 18.7%. Pain during a single-leg decline squat dropped from 7.0/10 to 0.17/10 immediately post-exercise in patients with patellar tendinopathy. However, results have been inconsistent across populations, and the analgesic effect appears to be more reliable in patellar tendinopathy than achilles. This approach is usually worth trying if it provides pain relief, if not, I generally skip it.
Short-duration, high-intensity isometrics (5 sets × 4 reps, 3s on/3s off) This is the protocol I lean toward more heavily, particularly for tendon remodeling. The mechanism is different: brief explosive contractions create what Keith Baar (8) describes as stress relaxation, a property of viscoelastic tissue where force decreases over time during static loading. In a tendon with pathology, healthy collagen fibers often "stress-shield" the injured region, preventing it from receiving adequate mechanical stimulation. Isometric stress relaxation reduces stiffness in the healthy tissue, allowing load to transfer through the damaged area. This is the theoretical basis for why high intensity isometrics may be uniquely suited to early-stage tendon remodeling.
Neuromuscular benefits are also well-documented. Short-duration explosive isometrics improve neuromuscular activation and rapid force development. I also tend to think that our return to play tests require short, maximal contractile efforts. So, why not train them throughout the rehab process.
Stage 2: Heavy Slow Isotonics
As pain allows, we progress to heavy slow resistance training. This is where the bulk of tendon structural remodeling occurs.
The mechanism is primarily increased tendon modulus (material stiffness) rather than cross-sectional area, meaning the tendon becomes stiffer through improved material properties, not just by getting bigger. Stiffness here is actually a good thing. We tend to relate the term stiffness to muscular stiffness, which we view as a negative. Again, the spring analogy is useful here. A stiff spring functions better than a loose spring. Effect sizes are meaningful: moderate increases in stiffness and large increases in modulus.
Parameters I use:
Frequency: 3x/week on non-consecutive days (max)
Volume: 3–4 sets, 4-12 reps depending on the phase
Tempo: 3–6 seconds per repetition (slow and controlled)
Load: Progressive, targeting high tendon strain over time
An important note on load magnitude: a recent study comparing heavy (90% 1RM) versus moderate (55% 1RM) protocols showed similar clinical outcomes when volume is equalized (9). The theoretical optimum is high strain magnitude (≥4.5–6.5% tendon strain, roughly 90% MVC), applied at low frequency. But in practice, the most important variable is often tempo and progressive overload rather than an exact percentage of 1RM. Starting moderate and building is safer and more sustainable.
Stage 3: Plyometrics and Change of Direction
This stage is where we often undersell ourselves clinically. I tend to think of building strength as “the thing that is remodeling the tendon”. Heavy slow strength training is challenging the tendon in a way it isn’t good at. Re-introducing plyometrics is where we allow the new mechanical properties of the tendon to shine. Tendons are extraordinary energy storage devices, their primary function in activities like running and jumping is elastic energy utilization through the stretch-shortening cycle (SSC). Heavy slow resistance is a stimulus for remodeling; plyometrics are the expression of tendon function.
The type of plyometric we use really depends on the tendon we are rehabbing. I tend to lean on Matt McInness Watson’s work (The Plyo Guy) to inform my plyometric prescription. As a general rule, I think it is best to build volume first before adding intensity. As intensity increases, we should drop volume.
In this phase, I also start gentle change of direction drills. I like the agility ladder because we are working on motor planning and controlled movements. We can easily progress this with increasing effort over the course of time. I also work on deceleration drills (starting slow and increasing speed and momentum), and 45 degree → 90 degree → 180 degree cuts.
Stage 4: Return to Running / Agility
Running is both a goal and a form of tendon loading in its own right. I frame return to running as:
Build volume first, then intensity. This mirrors ACWR-based load management principles.
Pull back on plyometric volume as running volume increases. Total tendon load is additive — don't stack too many high-demand activities simultaneously.
Maintain HSR throughout. Strength training doesn't stop when running returns; it continues as the long-term strategy for tendon health.
In terms of running prescription, it depends what type of sport the athlete is getting back to. If they are a runner, they really only need to get back to sagittal plane running. In most cases, I will start with walk:run progressions, reducing walking and increasing running until we are able to perform continuous runs. Once this is well tolerated, I will add in speed and tempo work.
For field or court sport athletes we need to get back to acceleration runs, top-end speed / build up runs, and continuous running as well as curvilinear running. We also turn out change of direction work into more traditional agility drills, with reaction to stimuli and changing environments.
Again, in this phase we try to maintain the qualities we built up in the previous stages, not stop them all together. But as running volume increases, we can’t also keep lifting and plyometric volume high. We just need to be calculated here and not layer stress on top of stress.
Modifying Aggravating Factors
Alongside the loading program, we need to address what's driving the tendinopathy in the first place. Tendons experience three types of load:
Tensile: Longitudinal pull along the collagen fibers. This is the dominant load and what tendons are built to handle.
Shear: Fibers gliding past each other; relevant in peritendon pathology.
Compression: Perpendicular force at entheses and bony prominences. This is the most clinically underappreciated — and often the primary driver at insertional sites like the insertional Achilles and proximal hamstring origin.
For insertional tendinopathies, compressive loads (stretching into end-range dorsiflexion for insertional Achilles, hip flexion for proximal hamstring tendinopathy) often need to be modified early. This is sometimes counterintuitive for patients who have been told to "stretch more." But there isn’t much sense in starting a loading program (adding stress), if we haven’t removed the proverbial ‘rock from the patient's shoe’.
Summary
Tendinopathy rehab is not complicated in principle. The hard part is managing patient expectations, keeping people moving when their instinct is to stop, and resisting the urge to chase passive interventions when the evidence keeps pointing back to progressive loading. Tendon rehab takes time, and fully resolving issues requires persistence.
