The first time I ignored outer ankle pain, I was four hours into a mountain race in Slovenia, and I told myself it was just a hot spot from my shoe lacing. By the time I crossed the finish line, the tendons running behind my outer ankle bone were so angry I could barely walk down the stairs to the dining hall. That was my introduction to peroneal tendinopathy, and it cost me eight weeks of running.
Since then I have rehabbed my own peroneals twice more (we ultra runners are slow learners) and worked through this exact issue with dozens of runners I train alongside. The protocol below is what I actually use. It is not glamorous, and it does not rush. But it works, and more importantly, it tends to stay fixed.
What Peroneal Tendinopathy Actually Is
Your peroneal tendons (peroneus longus and peroneus brevis) run down the outside of your lower leg, curve behind the lateral malleolus -- that bony bump on the outside of your ankle -- and attach into the foot. Their job is to evert the foot (turn the sole outward) and stabilise the ankle, especially on uneven ground.
Tendinopathy is what happens when load exceeds the tendon's capacity to adapt, over and over again, until the tissue starts to degrade rather than rebuild. It is not really an "inflammation" problem in the classic sense. It is a capacity problem. The tendon got asked to do more than it could handle, and the structure quietly broke down faster than it could repair.
For runners, the usual triggers are:
- Sudden jump in trail mileage, especially technical or off-camber terrain
- Switching to minimalist shoes too quickly
- Weak hips and glutes (the foot ends up doing stability work the hip should be doing)
- High supinated foot (heel rolls outward, peroneals work overtime to pull the foot back)
- Returning to running after an ankle sprain that never got fully rehabbed
The hallmark symptom is pain along the outer ankle and lower outer shin, usually worst during push-off and on descents. Single-leg balance feels wobbly. The tendon may feel thickened if you palpate just behind and below the lateral malleolus.
Before You Start: A Few Honest Words
I am a physiotherapist, not your physiotherapist. If your pain came on suddenly after a twist or fall, if you have visible swelling, bruising, or instability where the ankle gives way, you need an in-person assessment. Peroneal tendon tears, subluxation (where the tendon snaps over the bone), and fibular stress fractures can all mimic tendinopathy and they do not respond to the protocol below.
If the pain is gradual onset, related to load, no instability, and worse with running but better after warming up -- you are most likely in tendinopathy territory and this protocol fits.
The other thing I want to be upfront about: tendons are slow. The biology of tendon adaptation takes weeks, not days. If you commit to four to six weeks of consistent loading and then quit because progress feels invisible, you will end up restarting from zero. Trust the process.
The Four-Phase Protocol
The framework I use is the one most evidence-based tendon rehab follows: isometrics first, then heavy-slow resistance, then energy-storage (plyometric) work, then a graded return to the sport itself. Each phase has criteria you have to meet before moving on. You do not graduate by calendar; you graduate by capacity.
Phase 1: Isometrics (Pain Modulation and Reawakening) -- Week 1 to 2
Isometric contractions -- holding a muscle tense without movement -- are where I start everyone, including myself. They calm the pain signal down, get the tendon used to load again in a controlled way, and start rebuilding the brain-muscle connection that often goes quiet when something hurts.
The exercise: Resisted isometric eversion
Sit on the floor with your leg out straight. Loop a resistance band around the outside of your forefoot and anchor it to something solid on your inside (a heavy table leg works). Without moving your foot, push outward against the band as if turning the sole away from your other leg. Hold for 45 seconds. Rest 1 to 2 minutes. Repeat 5 times.
Do this twice a day. The contraction should feel firm but not produce pain above a 3 out of 10. If it does, lighten the band and shorten the hold to 30 seconds.
Add: Single-leg standing balance
Eyes open, 30 seconds. Then eyes closed, 30 seconds. Three rounds, twice a day. Yes, it feels too simple. Do it anyway. The peroneals are heavily involved in standing balance and you are giving them a low-grade tonic stimulus.
Criteria to move on: You can do all 5 isometric holds without pain spiking above 3/10 during or after, and morning stiffness in the ankle has reduced.
This usually takes 7 to 14 days. For some of my runners, less. For my friend Petar who tried to run through it for two months before calling me, it took nearly three weeks just to get to Phase 2.
Phase 2: Heavy-Slow Resistance (Building Tendon Capacity) -- Week 3 to 6
This is where the actual rebuilding happens. The principle: load the tendon with heavy resistance through a slow, controlled range. The slowness is the point. Three seconds up, a pause, three seconds down. Heavy enough that the last two reps of a set of 8 are genuinely hard.
Exercise A: Heavy banded eversion (full range)
Same setup as the isometric, but now you move. Slowly evert your foot against the band, pause at the end, slowly return. Three seconds out, one second hold, three seconds back. 3 sets of 8 reps. Use a band heavy enough that rep 8 is a struggle.
Exercise B: Single-leg heel raise with bias
Stand on one foot on the edge of a step. Slowly raise up onto the ball of your foot (3 seconds), pause at the top, slowly lower below the step (3 seconds). 3 sets of 8 to 10 reps.
Here is the peroneal-specific tweak: as you rise up, deliberately push more weight through the outside of your big toe and ball of foot. This biases the lift toward the peroneus longus. If single-leg is too much initially, start with both feet and progress.
Exercise C: Lateral step-down
Stand sideways on a low step (10-15 cm). Slowly lower the opposite foot toward the floor, controlling everything with the leg on the step. 3 sets of 8. The peroneals will fire to keep your ankle from collapsing inward.
Do this routine three days a week, with at least 48 hours between sessions. Tendons respond to load but they also need recovery to adapt.
Between sessions: This is where I recommend an ankle compression sleeve. Not as a brace or a fix -- the rehab is the fix -- but as a way to manage load on the days you are walking around, standing in your kitchen, going to work. Mild compression supports proprioception, can take the edge off mid-day soreness, and helps with the low-grade swelling that often hangs around in early rehab. I have my callanetics students who run on the side wear the HYKLE Ankle Compression Socks on rehab days specifically for this reason. Off during sleep, off during your loading sessions, on during regular daily movement.
Criteria to move on: You can complete all three exercises at a meaningful load (heavy enough that rep 8 is hard), pain stays at or below 3/10 during and within 24 hours after, and you have done at least 9 sessions (3 weeks).
Phase 3: Energy Storage and Plyometrics -- Week 6 to 9
Running is not a slow controlled exercise. It is a series of rapid loading and unloading cycles where the tendon stores and releases elastic energy roughly 180 times per minute. If you go from heavy-slow rehab straight back to running, you will skip the link in the chain that prepares the tendon for sport-specific stress. That is when reinjury happens.
This phase trains the tendon to handle rapid loading.
Exercise A: Pogo hops in place
Two-foot small bouncing hops, staying tall, contacting the ground with stiff but springy ankles. 3 sets of 20 to 30 seconds. The peroneals are highly active in keeping the ankle from collapsing on each landing.
Exercise B: Lateral skater hops
Hop sideways from one foot to the other, landing softly, holding the landing for 1 second before springing back the other way. Start small. 3 sets of 10 reps each side.
Exercise C: Single-leg hops in place
Once skater hops feel solid: small bouncing hops on one foot, 3 sets of 15-20. This is the closest single exercise to running mechanics for the peroneals.
Exercise D: Forward-backward hops on a line
Hop forward over a line on the floor, then immediately backward. 3 sets of 20. Then sideways the same way. This adds the multi-directional demand trail running puts on the ankle.
Two sessions per week. The other days, keep doing your heavy-slow resistance work because you are not done building capacity -- you are just adding a new layer on top.
Criteria to move on: All plyometric exercises performed with pain at or below 2/10, no soreness lingering more than 24 hours, single-leg balance with eyes closed is solid for 30+ seconds.
Phase 4: Return to Trail -- Week 9 Onward
I see runners blow this phase more than any other. They get to week 8, the ankle feels great, and they go out for "just an easy 10K on the trails." A few days later, the pain is back, they blame the rehab, and they message me asking what went wrong.
What went wrong is they skipped the graded return.
Week 1 of return: Flat surface only -- track, smooth path, treadmill. Run-walk intervals. I usually start runners with 5 x (3 min run, 2 min walk). Two sessions, three days apart.
Week 2: Same flat surface, continuous easy running. Start with 20 minutes. Add 5 minutes per session. Three sessions per week, never on consecutive days.
Week 3: Introduce gentle rolling terrain -- nothing technical, no scree, no off-camber paths. Forest fire roads are perfect. Same volume as week 2.
Week 4: Mild technical trails. Roots and rocks, but nothing where the foot is forced into deep lateral angles.
Week 5+: Gradual return to your normal trail terrain. Add steep descents last -- they load the peroneals hardest.
Throughout this return, keep doing the heavy-slow resistance work twice a week. Forever, honestly. I do mine year-round now and have not had a peroneal flare in over four years.
Rules during the return phase:
- Pain during a run that climbs above 3/10: stop, walk home, take 48 hours off, drop back a step in the progression.
- Pain the morning after that is worse than the morning of the run: same response.
- Pain that fades within 5 minutes of running and stays gone: keep going, you are fine.
What Else Matters
Footwear. I am a barefoot shoe wearer myself and a believer in foot strength, but if you developed peroneal tendinopathy partly from switching to minimalist shoes too fast, do not do your rehab and return-to-run in barefoot shoes. Use a neutral, modestly cushioned trainer through the return phase. You can transition back to your minimalist preference once you are running pain-free for 6+ weeks. I have written more about getting that transition right in our winter barefoot shoe article -- the timing principles apply year-round.
The hip and glute side of the equation. Weak hip abductors and external rotators force the lower leg to do stability work it was not designed for. If you have not been doing lateral hip strength work, add it. The knee strengthening exercises I give every runner overlap heavily with what your peroneals need from the hip -- the same chain of stability runs from glute through to foot.
Sleep and stress. Tendons heal during sleep. If you are sleeping 5 hours a night and burning the candle at both ends, your rehab will stall. I noticed this in my own body after my second baby -- I was doing the right exercises but recovering at half speed because I was running on broken sleep.
Patience. I keep saying this because it matters. Twelve weeks is a realistic minimum to get from "this hurts every run" to "I am back on technical trail without thinking about it." Some people take 16. Almost nobody does it in 6.
A Note on When to Get Help
If you are 4 weeks into Phase 1 and isometrics are still painful at 5+ out of 10, something else is going on. Get an in-person assessment. The same is true if you ever feel a popping or snapping sensation behind your outer ankle bone -- that can be peroneal subluxation and it is a different beast that sometimes needs surgical input.
For everyone else: the protocol works because tendons respond to load, full stop. Give them the right load, in the right order, for long enough, and they rebuild. The hard part is not the science. The hard part is doing boring isometric holds for two weeks when what you want is to be running on a ridge somewhere.
Do them anyway. You will get back to the ridge. And next time, your ankle might just hold up.