A summary of “How do tendons adapt? Going beyond tissue responses to understand positive adaptation and pathology development” (Docking & Cook, 2019).
The short version (for busy humans)
– Tendons do respond to load — but they adapt slowly and on their own timetable.
– Feeling “fitter” in a few weeks doesn’t mean your tendons are ready for more; that mismatch is when injuries happen.
– Pathology ≠ pain. Many people have “abnormal” scans and no symptoms. Your load capacity can improve even if the scan doesn’t look perfect.
– The goal of rehab isn’t a pretty image — it’s better load tolerance: doing more, more often, with fewer symptoms.
What do we mean by “adaptation”?
Adaptation is simply your body getting better at handling what you ask of it. With tendons, that mainly happens through loading — tensile (pulling), compression, and shear. You can think of your capacity like a dial: appropriate load turns it up; long periods of no load turn it down.
Scientists sometimes describe a tendon “mechanostat”: a shifting threshold where load triggers either a positive response or a negative one. Good programming nudges that threshold upwards over time; under-loading or big spikes can nudge it down.
What actually changes in a tendon?
1) Size (cross-sectional area)
– In younger people (before/around puberty), tendons may grow thicker with years of sport.
– In adults, size changes are small or inconsistent — and a lack of size change does not mean you’re not adapting.
2) Mechanical properties (how stiff/compliant it is)
– Right after a hard session, tendons are temporarily less stiff (hours to ~24h). That’s a normal, reversible response.
– Over months of good training, tendons often become stiffer/stronger — useful for power and force transfer.
– The “best” stiffness is sport-specific: power athletes often benefit from more stiffness; endurance athletes may benefit from some compliance.
3) Internal structure (what imaging sees)
– Short-term loading can change ultrasound/MRI signals (water content, fibre wave/organisation). These shifts don’t automatically mean harm — they can be normal responses.
– With months of progressive training, some studies show more organised patterns — but again, images don’t tell the whole story.
4) Blood flow
– Blood flow in and around tendons can increase immediately after exercise and then return to baseline. On its own, this isn’t a diagnosis of injury.
Key point: tissue changes ≠ guaranteed performance change. What matters most is whether you can do more, more often, with fewer symptoms.
Why scans don’t tell the whole story
Lots of active people have asymptomatic tendon “pathology” on imaging and function perfectly well. In painful tendons, structure often doesn’t fully normalise, yet people still get stronger, perform better, and stay pain-free.
How? Your body compensates and adapts — the healthy parts of the tendon, the muscle, and the nervous system pick up the slack. That’s why rehab can succeed even if a scan still looks “imperfect”.
What this means for training and rehab
1) Progress slower than your lungs want
Cardiovascular fitness improves fast; tendon adaptation is months, not weeks. Respect the lag.
2) Use minimum effective dose and build
– Start with loads your tendon tolerates without next-day flare-ups.
– Add small steps (volume or intensity, not both) each week.
– Keep 48–72 hours between heavy tendon sessions early on.
3) Prioritise heavy, slow strength work
– Isolated, single-joint loading (e.g., calf raises for Achilles; knee-dominant loading for patellar tendon; wrist/finger loading for lateral elbow) has the strongest effect on tendon properties.
– Think 3–4 sets of 6–10 reps at a challenging effort, 2–3×/week, progressed gradually.
4) Plyometrics are great — at the right time
– Introduce hops/jumps/changes of direction after a base of heavy slow work.
– Start with low contacts and short ground times, then build.
5) Don’t chase a perfect scan — chase capacity
– Your north star is: Can I do more, more often, with symptoms under control?
– Use pain as information, not an emergency brake. A 0–3/10 discomfort that settles within 24 hours is usually acceptable; persistent >24–48h flares mean you progressed too fast.
6) Consistency beats intensity
– If you miss a day, don’t miss a week. If you miss a week, don’t miss two.
– Modify when irritated; don’t abandon everything.
When to get help
– Pain that doesn’t settle within 24–48 hours after easy loading.
– Repeated flare-ups when you increase either volume or intensity.
– You’re unsure how to progress without going in circles.
We’ll test your current load capacity, design an appropriate loading plan, and help you build strength, tolerance and confidence.
Last updated: 24th October 2025
