Tendinitis vs. Tendinosis: The Actual Rehab Framework (Part 2)
In Part 1, we covered the difference between tendinitis and tendinosis, and why treating one like the other is a common reason tendon pain drags on far longer than it should. This post is the part most people actually want: what does the rehab itself look like once a tendon is past the acute, calm-it-down phase and ready to be loaded back up.
There's nothing flashy here. It's not a 12-week periodized program. It's a framework I use with almost every tendon issue that walks through the door, whether it's a shoulder, an elbow, a knee, or an Achilles.
Start Where It's Boring: Isometrics
The starting point is almost always an isometric hold: a muscle contraction with no movement, held in a neutral, comfortable position. I'll usually start with 30 seconds, for three sets, in whatever range feels the safest and least provoking.
If that's tolerated well, the next step is working that same isometric hold through more of the available range, not just the easy spot. The goal is to distribute load across the full range the tendon actually has to deal with in real life, not just the pain-free portion of it.
Eventually, you're working your way toward holding right at the point where symptoms would normally start. Take a bench press, for example. If someone's shoulder is irritated near the bottom of the movement, they don't get to stay at 12 inches off the chest forever. Over time, that hold moves to 6 inches, and eventually to a full-depth hold. The tendon has to relearn how to tolerate load in the position that's actually giving it trouble, not just in the position that's easy.
Adding Eccentrics Without Dropping the Isometrics
Once someone can tolerate isometric holds through most of that range, that's the signal to start layering in eccentric work. Eccentrics are the slow, controlled lengthening portion of a movement, and they're one of the better-studied tools for actually remodeling tendon tissue.
I don't pull the isometrics out when eccentrics get added in. A typical setup might be one or two sets of isometric holds, followed by a third set of slow eccentrics, something like 5 to 10 seconds per rep, for 5 to 8 reps. Using the same bench press example, that third set becomes slow negatives.
The isometrics stick around because they're still doing a job the eccentrics aren't. You're not graduating away from one phase into the next so much as building layers on top of each other.
The Pain Rule That Actually Matters
People want a hard rule for how much discomfort is acceptable during this process, and there is one, but it's less about a single number and more about two patterns.
During the exercise itself, staying in the 2 to 4 out of 10 range is generally fine. What matters more than that number is whether it's climbing rep over rep, set over set, or staying flat. Pain that's steady at a 3 is a very different signal than pain that starts at a 2 and keeps building. Steady pain is what we're after, not pain that gradually climbs toward the edge of what you can tolerate.
The second piece is what happens afterward. Some soreness after loading a cranky tendon is normal. What's not normal is pain that lingers well past an hour or so after you're done. If you're still feeling it that evening, or it's noticeably worse the next morning, that's a sign the dose was too much for where the tissue is right now, not a sign to push through it next time.
It's Not Just the Tendon, It's the Movement
Here's a piece that gets missed constantly: you can do a technically perfect job rehabbing the tendon itself and still have the problem come right back if the movement mechanics around it are poor.
This matters most for what I'd call stabilizing tendons, things like the rotator cuff, where the tendon's job is less about handling one big load and more about controlling a joint through a wide range of everyday movement. Good scapulohumeral control, meaning how well the shoulder blade and upper arm coordinate through pushing and pulling, is fundamental to protecting that tendon once it's back under load.
Load-bearing tendons like the patellar tendon or Achilles are protected by a different mechanism. Their job isn't stabilizing a joint through a range of motion, it's handling raw force, and that force gets distributed through the whole chain during a movement like a squat or hinge. If the hips and glutes aren't doing their share, the knee or ankle ends up absorbing load that should have been shared out, and the tendon takes the hit. So for these tendons, it's squat and hinge mechanics specifically that matter, not the pushing and pulling patterns that protect a tendon like the rotator cuff.
If the tendon heals well but the underlying movement skill never gets addressed, the fix tends to take much longer to fully resolve, and it tends to come back. So the coordination and skill side of a lift or movement pattern isn't a side note. It's another layer of the rehab itself, right alongside the loading progression.
Judging Progress by the Week, Not the Workout
Figuring out exactly how much rehab work someone should be doing isn't an exact science. It's closer to an ongoing experiment than a fixed prescription. Even a well-structured routine can overload healing tissue if there's simply too much of it.
Because of that, the right time horizon for judging whether something's working is a week, not a single session. If someone's feeling more symptoms 24 to 48 hours after a workout, that's the cue to back off, whether that means taking a day or two off entirely or just scaling back the volume within a session.
One of the most useful markers isn't even in the gym. It's daily life. Morning pain, discomfort going up and down stairs, or whatever that person's specific everyday trigger happens to be. As rehab is working, those everyday symptoms should be gradually fading. If they're staying flat or getting worse instead, that's the real signal to adjust the routine, often before the training itself even tells you something's wrong.
The Takeaway
When it comes to navigating pain, there's no script that works for everybody. But rehab still needs the right starting point to get the result you're after, and that starts with understanding the itis versus osis conversation from Part 1.
From there, the framework is straightforward. Calm things down or load them up, depending on which one you're actually dealing with. Start with isometrics, then add eccentrics without dropping the isometrics. Stay within a pain range that holds steady instead of escalating or lingering. Fix the movement mechanics around the tendon, not just the tendon itself. And judge progress by the week and by daily life, not by any single workout.
Follow this framework and you should find success. From here, what's standing in your way isn't the plan, it's consistency and ego. Keep up with the exercises, and don't be too quick to jump back into the deep end before you're actually ready.
