Eccentric heel drops are the most studied and widely recommended exercise for Achilles tendonitis. The original protocol, developed by Swedish researcher Hakan Alfredson, calls for 180 repetitions per day over 12 weeks. But “best” depends on where your pain is located, how long you’ve had it, and what you can tolerate. Several exercise approaches have strong evidence behind them, and the right one for you may not be the most famous one.
Why Exercise Works for Tendon Pain
Achilles tendonitis (more accurately called tendinopathy) involves a breakdown in the tendon’s internal structure rather than classic inflammation. The tendon’s collagen fibers become disorganized, and the tissue loses its ability to handle load efficiently. Exercise works because mechanical stress on tendon cells triggers them to produce new type I collagen, the primary structural protein in tendons. This process leads to a stiffer, thicker, more resilient tendon over time.
The key is that the load has to be appropriate. Too little stress and the tendon doesn’t get the signal to rebuild. Too much and you overwhelm already compromised tissue. That’s why structured loading programs, not rest alone, are the foundation of treatment. The tendon needs controlled, progressive stress to remodel itself.
Eccentric Heel Drops: The Standard Protocol
Eccentric heel drops remain the most researched exercise for midportion Achilles tendonitis, the type that causes pain in the middle of the tendon a few centimeters above the heel bone. The exercise is simple: you rise up on your toes using both feet, then slowly lower your heel below the edge of a step using only the affected leg. The lowering phase is the eccentric portion, where the calf muscle lengthens under load.
The standard protocol is demanding. You perform 3 sets of 15 repetitions twice daily, once with a straight knee and once with a bent knee, totaling 180 repetitions per day. This continues for 12 weeks. A five-year follow-up study published in the British Journal of Sports Medicine confirmed lasting benefits from this program, though the time commitment is significant. You can add weight using a loaded backpack once the exercises become pain-free at body weight.
One important caveat: this protocol was designed for midportion tendonitis specifically. If your pain is right at the back of the heel where the tendon attaches to the bone, you have insertional tendonitis, and the standard heel drop can actually make things worse.
Insertional vs. Midportion: Location Changes Everything
The Achilles tendon can develop problems in two distinct zones, and the exercises that help one can aggravate the other. Midportion tendonitis affects the body of the tendon, typically 2 to 6 centimeters above the heel. Insertional tendonitis affects the point where the tendon anchors to the heel bone.
With insertional tendonitis, dropping your heel below a step creates compressive force where the tendon presses against the back of the heel bone. This compression at the insertion point tends to increase pain rather than reduce it. The fix is straightforward: perform your heel drops from the flat ground instead of a step, so your heel never drops below neutral. Research on eccentric training without dorsiflexion (that below-step stretch) has shown good outcomes for insertional cases. If you’re unsure which type you have, the location of your tenderness when you pinch the tendon will usually tell you.
Heavy Slow Resistance Training
Heavy slow resistance (HSR) training is an alternative that some people find more practical and equally effective. Instead of high-repetition bodyweight exercises, HSR uses heavier loads at slower speeds, typically gym-based calf raise variations performed with a 6-second tempo per repetition (3 seconds up, 3 seconds down).
The principle behind HSR is that tendons need to be loaded above roughly 70% of your maximum capacity to trigger meaningful adaptation. Common HSR protocols use a progression across sets, starting with higher repetitions and lighter weight and building toward heavier loads with fewer repetitions over the course of several weeks. Recent biomechanical analysis suggests that keeping repetitions below 6 per set at that slow tempo ensures you’re actually hitting the intensity threshold tendons need. One practical approach uses small clusters of 3 repetitions with short 15-second rest periods between them, allowing you to maintain about 85% of your maximum load while accumulating enough volume.
HSR takes less total time per day than the Alfredson protocol and is performed three times per week rather than daily. For people who find 180 daily repetitions unsustainable, this can be a more realistic long-term option. Clinical trials comparing HSR to eccentric training have found similar outcomes at 12 weeks.
Isometric Holds for Early Pain Relief
If your Achilles is too irritable for dynamic exercises, isometric contractions (holding a position without movement) can serve as a starting point. A typical approach involves 5 sets of 45-second holds: 2 sets seated with the knee bent, followed by 3 sets standing with the knee straight. You hold a calf raise position, either on your toes or in a neutral ankle position, and sustain the contraction against resistance.
Isometric exercises were initially promoted as providing immediate pain relief for tendon problems, but a clinical trial specific to Achilles tendinopathy found the analgesic effect was not as reliable as once thought. They still have value as a way to begin loading the tendon when it’s too sensitive for repetitive movement. Think of them as a bridge to the more demanding programs rather than a standalone treatment.
How to Manage Pain During Exercise
Some discomfort during tendon-loading exercises is expected and acceptable. A pain-monitoring approach has been tested in clinical trials, where patients continued activities like running and jumping alongside their rehabilitation as long as they stayed within tolerable pain levels. Researchers found no negative effects from maintaining activity with this model compared to complete rest from sport.
A practical guideline many clinicians use is a 0 to 10 pain scale. Pain up to about 3 or 4 out of 10 during exercise is generally considered acceptable. If pain spikes above 5 during the session, or if your baseline pain is worse the morning after exercise compared to the morning before, you’ve likely done too much. Dial back the load, the number of repetitions, or both, and build up more gradually.
Realistic Recovery Timelines
Achilles tendonitis is not a quick fix. In a clinical trial tracking patients through exercise therapy, all groups met a clinically meaningful improvement in symptoms by 8 weeks. By 16 weeks, patients showed improvements across symptoms, physical function, tendon structure on imaging, and psychological factors like confidence in their tendon. The duration of your symptoms before starting treatment didn’t significantly change the trajectory at 16 weeks, which is encouraging if you’ve been dealing with this for months.
That said, 16 weeks represents an average improvement point, not a finish line. Many people continue to see gains for 6 to 12 months. The tendon remodeling process is slow because tendons have limited blood supply and low metabolic activity compared to muscle. Consistency matters more than intensity in the early weeks. Skipping sessions or abandoning the program at week 4 because you don’t see results yet is the most common reason people don’t improve.
Putting Together a Practical Plan
Start by identifying whether your pain is at the insertion (right at the heel bone) or in the midportion (a few centimeters higher). For midportion tendonitis, standard eccentric heel drops off a step are your first-line option. For insertional tendonitis, perform the same movement from flat ground so your heel stays at or above neutral.
If the full Alfredson protocol of 180 daily repetitions feels overwhelming, heavy slow resistance training three times per week is a well-supported alternative. If your tendon is currently too irritated for either approach, begin with isometric holds for 1 to 2 weeks to build tolerance, then transition into a progressive loading program.
Whichever approach you choose, plan for at least 12 weeks of consistent work before evaluating whether it’s helping. Expect noticeable improvement around 8 weeks, with continued gains through 16 weeks and beyond. The exercise itself is the treatment, not a supplement to some other intervention. Loading the tendon progressively and patiently is the single most effective thing you can do.