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Tendon Recovery · Load It, Don't Just Rest It
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In one pass The collagen in the core of a tendon is laid down during the years when you are growing, and it barely renews in adulthood.
Educational content, not medical advice — consult a clinician.
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Chapter 1
Why tendons heal slowly
The collagen in the core of a tendon is laid down during the years when you are growing, and it barely renews in adulthood. That is the structural reason an injured tendon heals slowly.
A pulled muscle can mend in two or three weeks, while tennis elbow or Achilles pain can drag on for months. That is not because you are not trying hard enough; this tissue simply has few cells, a poor blood supply and a slow metabolism. Slow does not mean it cannot be repaired: the switch that drives its repair surprises many people — it is not rest, but the right amount of load.
One situation is not a matter of healing slowly: a sudden, severe pain, a pop you hear or feel, and then being unable to push off or rise onto your toes, or feeling a gap in the tendon. Suspect a tendon rupture (an Achilles rupture, for example). That is an emergency: seek care promptly, and do not try to train through it.
A pulled muscle can mend in two or three weeks, while tennis elbow or Achilles pain can drag on for months. That is not because you are not trying hard enough; this tissue simply has few cells, a poor blood supply and a slow metabolism. Slow does not mean it cannot be repaired: the switch that drives its repair surprises many people — it is not rest, but the right amount of load.
One situation is not a matter of healing slowly: a sudden, severe pain, a pop you hear or feel, and then being unable to push off or rise onto your toes, or feeling a gap in the tendon. Suspect a tendon rupture (an Achilles rupture, for example). That is an emergency: seek care promptly, and do not try to train through it.
Mechanism · Why tendon is strong but slow to mend
The bulk of a tendon is dense type I collagen, laid down in parallel bundles built to pass the pull of a muscle on to the bone. It is one of the connective tissues with the highest tensile strength in the body.The cells that maintain it, called tenocytes, sit sparsely in the collagen matrix: few in number and low in metabolism. Compared with muscle, tendon has a poor blood supply — few vessels, little oxygen, a low metabolic rate. That is the first reason it heals slowly.
So tendon does not fail to heal; it renews extremely slowly. And precisely because it is slow, it is fussy about what you use to stimulate repair. This was later pinned down at the molecular level by a natural experiment.
Evidence · How bomb carbon-14 dated tendon collagen
Heinemeier and colleagues in 2013 used a natural experiment. The nuclear bomb tests of 1955-1963 sharply raised the carbon-14 in the atmosphere, and every living thing recorded those years' carbon-14 levels in its body, like a timestamp. The researchers measured carbon-14 in the core of adult Achilles tendons from forensic samples, and the levels matched the atmosphere from before each person turned 17 — the years of growing taller.What it means: collagen in the core of a tendon is laid down while you grow and is barely renewed in adulthood, in sharp contrast to muscle, which turns over continuously. That explains at the molecular level why tendon heals slowly once injured and becomes more brittle with age. And the switch that stimulates its repair surprises many people: not rest, but load.
Articular cartilage is a similar tissue without blood vessels, and it too is fed and repaired by load (see Exercise as medicine).
Chapter 2
Chronic tendon pain isn't inflammation
Cut open a tendon that has hurt for months and you find few of the classic inflammatory cells. What you see is disorganized collagen, a matrix that is breaking down, and abnormal blood vessels and nerves growing in. This is a failed repair, not inflammation.
So the more accurate name is not tendinitis but tendinopathy, or tendinosis. This is more than a change of label: if the lead actor is not inflammation, then ice, anti-inflammatory drugs and repeated steroid shots can only damp the symptoms; they cannot fix the disordered collagen.
Nor does the damage appear overnight. It is more like a spectrum, from an early reaction that can still settle down to degeneration that is very hard to reverse; and carbon-14 measurements show that a diseased tendon had already been turning over abnormally for several years before the pain appeared.
So the more accurate name is not tendinitis but tendinopathy, or tendinosis. This is more than a change of label: if the lead actor is not inflammation, then ice, anti-inflammatory drugs and repeated steroid shots can only damp the symptoms; they cannot fix the disordered collagen.
Nor does the damage appear overnight. It is more like a spectrum, from an early reaction that can still settle down to degeneration that is very hard to reverse; and carbon-14 measurements show that a diseased tendon had already been turning over abnormally for several years before the pain appeared.
Mechanism · Under the microscope, degeneration
For decades we called it tendinitis and assumed it was inflammation, so the first reflex was ice, anti-inflammatory pills and rest until it stops hurting. That approach is fine for an acute strain, but for chronic tendon pain that has dragged on for months it is aimed at the wrong target from the start.Cut open a chronically painful tendon and there are few of the classic inflammatory cells. The collagen is disordered, the matrix is breaking down, abnormal vessels and nerves have grown in, and the tenocytes have changed shape. This is degeneration, not inflammation. The core mechanism is a failed healing response: the tendon is hit again and again by loads beyond its capacity to repair, and the half-repaired collagen is disorganized and weak.
Because the lead actor is not inflammation, anti-inflammatory approaches on their own — long-term anti-inflammatory drugs, repeated icing, steroid injections — are pressing on a fire that is not there: symptom relief at best, and possibly harmful. The long-term cost of steroid injections has its own chapter, Treatment and the cost of steroid shots. What actually needs fixing is the failed repair and the disordered collagen.
Evidence · Years of failed repair before the pain
In 2009, Cook and Purdam proposed a much-cited model that places tendinopathy on a continuous spectrum, explaining why the same kind of tendon pain clears up in weeks for one person and becomes stubborn chronic pain for another. It is a model built from pathology and clinical presentation, not a trial:Reactive stage: a short-term spike in load triggers a stress response in tenocytes and matrix that can still reverse; cut the load back and wait, and it can settle down.Dysrepair stage: the body attempts repair but fails, and the matrix starts to become disorganized.Degenerative stage: large areas of collagen lose their order, cells die and abnormal vessels appear. This stage is largely irreversible, and the goal shifts to making the surrounding healthy tissue stronger to compensate.
Heinemeier and colleagues in 2018 used carbon-14 again, with a more sobering result: healthy adult tendon barely turns over, but diseased tendon showed a great deal of collagen turnover, and modeling suggested this abnormally high turnover had been running for several years before pain appeared. The pain you feel today is a signal that surfaces only after the tendon has been quietly struggling to repair itself for a long time. No wonder it does not clear up in a few days, and no wonder it stopped hurting, so it has healed is so often an illusion.
The tool for repairing it is controlled mechanical load.
Chapter 3
Why load drives tendon repair
Tenocytes can sense stretch. Mechanical load, passing through the cell's internal skeleton and force-sensitive channels, is translated into a biochemical signal to make more collagen and rearrange the matrix. This process is called mechanotransduction.
So for chronic tendinopathy, complete rest while waiting for it to heal on its own often backfires: immobilization and long unloading make a tendon build less collagen and become thinner and weaker. What you do not use, you lose.
That does not mean training hard through pain. In the first few days of acute, severe pain you can rest relatively, cutting out the excess load that set it off, but do not stop moving altogether; after that, add load back little by little, using discomfort that is mild, bearable and no worse the next day as the upper limit of the dose.
So for chronic tendinopathy, complete rest while waiting for it to heal on its own often backfires: immobilization and long unloading make a tendon build less collagen and become thinner and weaker. What you do not use, you lose.
That does not mean training hard through pain. In the first few days of acute, severe pain you can rest relatively, cutting out the excess load that set it off, but do not stop moving altogether; after that, add load back little by little, using discomfort that is mild, bearable and no worse the next day as the upper limit of the dose.
Mechanism · How tension becomes a repair signal
Here is the most counterintuitive sentence about tendons: their repair signal comes mainly from mechanical load itself. Khan and Scott's 2009 review described the mechanism as mechanotransduction: tenocytes sense stretch, and mechanical load is translated into a biochemical signal that switches on collagen synthesis and remodeling of the matrix. In other words, tension tells the cells to repair, to build and to line up straight. The name they gave this framework is mechanotherapy: when a physical therapist prescribes exercise, they are essentially using controlled force to stimulate the tissue to repair itself.The reverse also holds: immobilization and long unloading lower a tendon's collagen synthesis, and it becomes thinner, weaker and less stiff. Keeping it still does not repair it; it lets it degenerate. That is also why the consensus on acute injuries has moved from complete immobilization (RICE) to early, controlled loading (details: see Training injuries).
In practice · Balancing rest and load
The right version of rest or load is this: in the first few days of acute, severe pain, rest relatively and cut out the excess load that set it off (de-load), rather than lying completely still. After that, add load back gradually and progressively, using discomfort that is mild, bearable and no worse the next day as the upper limit of the dose. The goal is not to wait until it stops hurting, but to actively rebuild the alignment and strength of the collagen.One piece of side evidence shows that a tendon's collagen machinery can be mobilized. Doessing and colleagues in 2010 gave healthy young adults recombinant growth hormone for 14 days: expression of the type I collagen gene in tendon rose to about 3.9 times its earlier level, actual collagen protein synthesis rose to about 1.3 times, and synthesis of the muscle's contractile (myofibrillar) protein did not change. This shows that tendon collagen is alive and can be stimulated, only with a different key from muscle. It is not a cue to inject growth hormone; it is a mechanism study, not a treatment recommendation.
Articular cartilage works the same way: moderate load feeds it, and long unloading makes it degenerate. Use it or lose it is the general rule of connective tissue (see Exercise as medicine).
Tendon is slow because it renews slowly; but it can be repaired, and the key is the right amount of tension, not the bed. How to use that key has already been turned into specific protocols by .
Chapter 4
How to load a tendon step by step
Tendon remodeling runs on controlled mechanical load. There are two main ways to turn that key into a prescription: eccentric training, where the muscle produces force while it is being lengthened (for example, standing on a step and slowly lowering the heel with the painful leg); and heavy slow resistance, strength training with fairly heavy weights, a very slow tempo and few repetitions.
This is not a slogan. In a of 58 people with chronic Achilles tendinopathy, both methods clearly improved symptoms over 12 weeks, and the gains held for a year; the heavy-slow group completed a higher share of its sessions. Pick the one you can stick to — sticking to it is part of what makes it work.
If it is too painful to train, you can start with isometric holds, such as a wall sit; training with a little pain that is bearable and no worse the next day is allowed. Tendons improve over weeks to months, not days.
This is not a slogan. In a of 58 people with chronic Achilles tendinopathy, both methods clearly improved symptoms over 12 weeks, and the gains held for a year; the heavy-slow group completed a higher share of its sessions. Pick the one you can stick to — sticking to it is part of what makes it work.
If it is too painful to train, you can start with isometric holds, such as a wall sit; training with a little pain that is bearable and no worse the next day is allowed. Tendons improve over weeks to months, not days.
Evidence · Eccentric and heavy slow resistance
Eccentric training, Alfredson's heel drop (1998, *AJSM*): a classic small study (n=15) without randomization. It had people with chronic Achilles tendinopathy do heavy-load eccentric calf raises every day: standing on a step, slowly lowering the heel with the affected leg. After 12 weeks, all 15 were back to running. Eccentric means the muscle produces force while it is being lengthened, and it is a particularly effective remodeling stimulus for tendon. Note the caveat: the sample was small, and it is a pioneering study rather than a final answer; but it sparked the whole approach of treating tendons with load.Heavy slow resistance (HSR): strength training with fairly heavy weights and a very slow tempo (for example, 3 seconds down and 3 seconds up) for few repetitions.
Beyer and colleagues 2015 (*AJSM*): 58 people with chronic midportion Achilles tendinopathy were randomly assigned to eccentric training or heavy slow resistance for 12 weeks. Both groups improved clearly in function, symptoms and pain during activity, and the gains held at the 52-week follow-up, equally well. The heavy-slow group completed a clearly higher share of its sessions; satisfaction was also slightly higher at 12 weeks, but by one year the two groups were about the same. Heavy slow resistance uses simpler movements and fewer sessions a week.Kongsgaard and colleagues 2009: 39 men with patellar tendinopathy were randomly assigned to a steroid injection, eccentric training or heavy slow resistance for 12 weeks. All three improved in the short term, but at the half-year follow-up the eccentric and heavy-slow groups had held their gains while the injection group had slipped back; heavy slow resistance also came with increased collagen turnover.
The practical takeaway: eccentric training and heavy slow resistance both work, so pick the one you will actually stick to — adherence is itself part of the effect.
In practice · How to set the loading dose
When it is too painful to train, start with isometrics (Rio and colleagues 2015, *BJSM*): a small crossover study. In people with patellar tendinopathy, isometric holds (the joint stays still while the muscle keeps working, as in a wall sit) brought immediate pain relief — the paper reported it lasting about 45 minutes — which let people get into the training that followed. To be honest: later attempts to repeat it gave mixed results, so do not treat it as magic; but as a stepping stone when it hurts too much to train, it is a reasonable choice.Dose principles that run through every protocol:
Load while monitoring pain (pain-monitoring): pain during training and in the 24 hours after, if it stays bearable and is no worse the next day, is acceptable. Tendon rehab allows training with a little pain, unlike a muscle strain.Progressive overload: add a little weight or a set every 1-2 weeks, to keep the remodeling signal reaching the collagen.Slowly: tendons improve over weeks to months, not days. A common mistake is it feels a bit better, so push hard and rush back to competition, which drops the tendon back into the reactive stage.
Midportion Achilles tendinopathy has a formal physical-therapy clinical practice guideline (*JOSPT* 2018) that lists progressive loading exercise as a recommendation at its highest grade, the one backed by strong evidence. This is load beats rest written into a guideline.
Chapter 5
How much collagen and vitamin C help
Collagen you eat is digested into amino acids; it does not travel intact to the tendon and patch itself on. Vitamin C, on the other hand, is an essential helper (cofactor) in making collagen: without it, collagen's triple helix — three strands twisted together — is unstable.
So eating enough protein and not being short of vitamin C is the nutritional foundation of tendon repair, and that layer is certain, cheap and applies to everyone.
One layer up, the evidence gets weaker. A small study found that eating vitamin C–enriched gelatin before exercise raised a blood marker of collagen synthesis; but it measured blood markers and ligaments grown in the lab, not tendon pain getting better faster. It is also a long way from the claim that bone broth fixes tendons. Nutrition plays a supporting role; load is the main treatment.
So eating enough protein and not being short of vitamin C is the nutritional foundation of tendon repair, and that layer is certain, cheap and applies to everyone.
One layer up, the evidence gets weaker. A small study found that eating vitamin C–enriched gelatin before exercise raised a blood marker of collagen synthesis; but it measured blood markers and ligaments grown in the lab, not tendon pain getting better faster. It is also a long way from the claim that bone broth fixes tendons. Nutrition plays a supporting role; load is the main treatment.
Mechanism · Protein and vitamin C as the foundation
Tendon is made of collagen, so eat collagen, drink bone broth to fix your tendons sounds self-evident. The honest version neither dismisses it outright nor lets marketing turn it into a myth.Making collagen needs plenty of amino-acid raw material, especially glycine and proline, and that comes first from eating enough total protein each day, not from a magic powder (the full picture of protein: see Protein & Amino Acids).
Vitamin C is an essential cofactor in making collagen: the two enzymes that add hydroxyl groups to proline and lysine (prolyl hydroxylase and lysyl hydroxylase) both depend on it. Without it, hydroxyproline cannot be made and the collagen triple helix is unstable. That is exactly why scurvy makes wounds split open and connective tissue fall apart (the full vitamin C mechanism: see Vitamin C).
So eating enough protein and not being short of vitamin C is the nutritional foundation of tendon repair. This layer is certain, cheap and applies to everyone.
Evidence · What pre-exercise gelatin actually showed
Shaw and colleagues in 2017 ran a small crossover study: participants took 15 g of vitamin C–enriched gelatin 1 hour before exercise, and afterward a blood marker of type I collagen synthesis (a propeptide) doubled. When the participants' serum was used to grow engineered ligaments in the lab, the ligaments' collagen content and mechanical properties also improved. The authors' proposed mechanism: supplying raw material and vitamin C before loading catches the window in which exercise stimulates collagen synthesis.An honest label: this is mechanistic evidence based on (blood markers, ligaments grown outside the body), not a clinical outcome such as tendon pain getting better faster; the sample was small, and bigger trials are needed. It is modestly promising, but far from a must-take.
Drawing a line against the bone-broth and collagen myths: claims such as bone broth heals joints and tendons, along with the promise that collagen reverses aging, mostly run far beyond the evidence. The collagen content and amino-acid makeup of bone broth are inconsistent, a long way from Shaw's measured dose of gelatin plus vitamin C timed with loading. The key difference: collagen you eat is digested into amino acids and does not arrive intact at the tendon; its value is raw material plus a possible timing effect, not like-fixes-like.
A practical way to eat, if you want to try it:
Build the foundation first: enough protein every day (for example 1.2-1.6 g/kg), and no shortage of vitamin C (food first; most people do not need large doses).To add Shaw's timing strategy: about 30-60 minutes before a rehab session, take about 15 g of collagen peptides or gelatin together with a little vitamin C. It is a bonus on top, not a replacement for the training.
Do not expect a supplement to work on its own: no nutrient can replace progressive loading as the main treatment. Nutrition plays a supporting role; load is the treatment.
Chapter 6
Treatment and the cost of steroid shots
The main treatment for chronic tendon pain is progressive load plus patience — not lying still, and not treating an injection as a repair.
In the first days of sudden, severe pain, cut the load back relatively but do not immobilize completely; after that, add load a little at a time, accepting discomfort that is bearable and no worse the next day.
As for injections: a systematic review of found that steroid (corticosteroid) injections relieve pain clearly in the short term (weeks), but at six months and a year the results are actually worse than with no injection. The reversal is clearest in the trials on tennis elbow. So an injection can occasionally be used for short-term pain relief, but it should not become routine treatment, and certainly should not be repeated.
Sudden severe pain with a pop and being unable to rise onto your toes, or a joint that is red, hot and swollen with a fever, needs prompt medical care. This site is popular science and does not replace a doctor.
In the first days of sudden, severe pain, cut the load back relatively but do not immobilize completely; after that, add load a little at a time, accepting discomfort that is bearable and no worse the next day.
As for injections: a systematic review of found that steroid (corticosteroid) injections relieve pain clearly in the short term (weeks), but at six months and a year the results are actually worse than with no injection. The reversal is clearest in the trials on tennis elbow. So an injection can occasionally be used for short-term pain relief, but it should not become routine treatment, and certainly should not be repeated.
Sudden severe pain with a pop and being unable to rise onto your toes, or a joint that is red, hot and swollen with a fever, needs prompt medical care. This site is popular science and does not replace a doctor.
In practice · A rehab route, and the cost of steroid shots
A general rehab route:1. The first days of sudden, severe pain: cut the load back relatively (drop the movement that overloaded it), but do not immobilize completely; keep moving within a pain-free range.
2. Move on to progressive loading: eccentric training or heavy slow resistance (HSR), whichever you can stick to; if it hurts too much to train, start with isometric holds to ease the pain.
3. Set the dose by pain: if pain during training and in the 24 hours after is bearable and no worse the next day, carry on; if it gets worse, drop back a step.
4. Progress over weeks to months: do not push hard just because it feels a bit better, and do not rush back to competition.
5. Nutrition as support: eat enough protein and do not run short of vitamin C; if you want to add more, try about 15 g of collagen peptides with vitamin C 30-60 minutes before a session.
An honest word on injections (Coombes and colleagues 2010, *The Lancet*): this systematic review pooled on the effectiveness and safety of corticosteroid injections and several other injections for tendinopathy. Many high-quality trials agreed: steroid injections clearly relieve pain in the short term (about 4 weeks), but in the intermediate and long term (roughly 6-12 months) that advantage reverses and the results are worse. The reversal is clearest in trials on tennis elbow (lateral epicondylalgia); for rotator cuff tendinopathy even the short-term effect is unclear. Serious adverse events were rare, but tendon rupture was reported. The review also found that several injections for Achilles tendinopathy, including platelet-rich plasma (PRP), did no better than placebo.
The mechanism makes sense: steroids suppress an inflammation that was never the lead actor, while possibly interfering with collagen repair and weakening the tendon. So an injection is not absolutely off-limits — short-term pain relief is useful in some situations — but it should not be the routine treatment for tendinopathy, and certainly should not be repeated. This is the real cost of thinking it is inflammation when it is degeneration.
Red flag · When to see a doctor
Signs to see a doctor or physical therapist (this site is popular science and does not replace a doctor): pain lasting more than 6-8 weeks, getting in the way of daily life or training, and not improving with your own progressive loading — see a physical therapist for an individual loading plan; to confirm whether it really is tendinopathy and not something else, you need a clinical assessment.Red flags (seek care promptly, and do not load it yourself): sudden severe pain, together with a pop, together with being unable to push off or rise onto your toes, or a gap you can feel — suspect a tendon rupture (such as an Achilles rupture); this is an emergency. A joint that is clearly red, hot and swollen, together with a fever — infection or inflammatory joint disease must be ruled out; this is not ordinary tendinopathy. Pain that wakes you at night, unexplained weight loss, or persistent pain unrelated to load — other causes must be ruled out.
Tendon heals slowly because it renews slowly and has a poor blood supply; chronic pain is failed repair, not inflammation. So the answer is not lying down and waiting, nor repeated anti-inflammatories, but well-judged, gradual, patient loading that presses the switch from tension to collagen remodeling back on. Once you know this mechanism, you will stop swinging between complete rest and pushing through the pain, and stop paying again and again for a needle that only treats the symptom.
References · 12
- Heinemeier, K. M., Schjerling, P., Heinemeier, J., Magnusson, S. P., & Kjaer, M. (2013). Lack of tissue renewal in human adult Achilles tendon is revealed by nuclear bomb 14C. The FASEB Journal, 27(5), 2074–2079. Bomb-pulse 14C in 28 forensic Achilles tendon core samples and 4 muscle samples: the tendon core retained 14C levels matching the atmosphere several decades before sampling, showing very limited tissue turnover, while muscle showed continuous turnover (abstract, PMID 23401563). 10.1096/fj.12-225599
- Cook, J. L., & Purdam, C. R. (2009). Is tendon pathology a continuum? A pathology model to explain the clinical presentation of load-induced tendinopathy. British Journal of Sports Medicine, 43(6), 409-416. 10.1136/bjsm.2008.051193
- Heinemeier, K. M., Schjerling, P., Ohlenschlaeger, T. F., Eismark, C., Olsen, J., & Kjaer, M. (2018). Carbon-14 bomb pulse dating shows that tendinopathy is preceded by years of abnormally high collagen turnover. The FASEB Journal, 32(9), 4763-4775. Diseased Achilles collagen had been renewed for years before pain; healthy adult core barely turns over. 10.1096/fj.201701569R
- Khan, K. M., & Scott, A. (2009). Mechanotherapy: how physical therapists' prescription of exercise promotes tissue repair. British Journal of Sports Medicine, 43(4), 247-252. 10.1136/bjsm.2008.054239
- Doessing, S., Heinemeier, K. M., Holm, L., Mackey, A. L., Schjerling, P., Rennie, M., Smith, K., Reitelseder, S., Kappelgaard, A.-M., Rasmussen, M. H., Flyvbjerg, A., & Kjaer, M. (2010). Growth hormone stimulates the collagen synthesis in human tendon and skeletal muscle without affecting myofibrillar protein synthesis. The Journal of Physiology, 588(2), 341–351. Healthy young adults given recombinant human GH 33-50 µg/kg/day for 14 days. Tendon collagen I mRNA rose 3.9-fold and tendon collagen protein synthesis 1.3-fold; in muscle, collagen I mRNA rose 2.3-fold and collagen protein synthesis 5.8-fold (P = 0.06). Myofibrillar protein synthesis was unaffected, and moderate exercise did not enhance the GH effect (abstract, PMID 19933753). 10.1113/jphysiol.2009.179325
- Alfredson, H., Pietilä, T., Jonsson, P., & Lorentzon, R. (1998). Heavy-load eccentric calf muscle training for the treatment of chronic Achilles tendinosis. The American Journal of Sports Medicine, 26(3), 360–366. 10.1177/03635465980260030301
- Beyer, R., Kongsgaard, M., Hougs Kjær, B., Øhlenschlæger, T., Kjær, M., & Magnusson, S. P. (2015). Heavy slow resistance versus eccentric training as treatment for Achilles tendinopathy: a randomized controlled trial. The American Journal of Sports Medicine, 43(7), 1704-1711. 58 patients with chronic (> 3 months) midportion Achilles tendinopathy randomized to eccentric training or heavy slow resistance (HSR) for 12 weeks. Both groups improved (VISA-A, pain), maintained at 52 weeks, with reduced tendon thickness and neovascularization; none of these clinical or structural outcomes differed between groups. Session compliance 92% HSR vs 78% eccentric (P < .005); satisfaction 100% vs 80% at 12 weeks (P = .052) and 96% vs 76% at 52 weeks (P = .10) (abstract, PMID 26018970). 10.1177/0363546515584760
- Kongsgaard, M., Kovanen, V., Aagaard, P., Doessing, S., Hansen, P., Laursen, A. H., Kaldau, N. C., Kjaer, M., & Magnusson, S. P. (2009). Corticosteroid injections, eccentric decline squat training and heavy slow resistance training in patellar tendinopathy. Scandinavian Journal of Medicine & Science in Sports, 19(6), 790–802. Single-blind RCT, 39 men with patellar tendinopathy: corticosteroid injection, eccentric decline squats or heavy slow resistance for 12 weeks. All groups improved at 12 weeks; at the half-year follow-up the gains held with eccentric and HSR training but deteriorated in the corticosteroid group. HSR had the highest satisfaction and increased collagen turnover (abstract, PMID 19793213). 10.1111/j.1600-0838.2009.00949.x
- Rio, E., Kidgell, D., Purdam, C., Gaida, J., Moseley, G. L., Pearce, A. J., & Cook, J. (2015). Isometric exercise induces analgesia and reduces inhibition in patellar tendinopathy. British Journal of Sports Medicine, 49(19), 1277–1283. 10.1136/bjsports-2014-094386
- Martin, R. L., Chimenti, R., Cuddeford, T., Houck, J., Matheson, J. W., McDonough, C. M., Paulseth, S., Wukich, D. K., & Carcia, C. R. (2018). Achilles pain, stiffness, and muscle power deficits: midportion Achilles tendinopathy revision 2018. Journal of Orthopaedic & Sports Physical Therapy, 48(5), A1-A38. 10.2519/jospt.2018.0302
- Shaw, G., Lee-Barthel, A., Ross, M. L. R., Wang, B., & Baar, K. (2017). Vitamin C-enriched gelatin supplementation before intermittent activity augments collagen synthesis. The American Journal of Clinical Nutrition, 105(1), 136-143. 8 healthy men, randomized double-blind crossover: 5 g or 15 g vitamin C-enriched gelatin or placebo 1 h before 6 min of rope-skipping, 3 times a day for 3 days. Blood glycine, proline, hydroxyproline and hydroxylysine peaked 1 h after the drink; with 15 g gelatin, blood amino-terminal propeptide of collagen I (PINP) doubled; serum drawn after gelatin raised collagen content of engineered ligaments in vitro. A collagen-synthesis marker; no injury or recovery outcome was measured (abstract, PMID 27852613). 10.3945/ajcn.116.138594
- Coombes, B. K., Bisset, L., & Vicenzino, B. (2010). Efficacy and safety of corticosteroid injections and other injections for management of tendinopathy: a systematic review of randomised controlled trials. The Lancet, 376(9754), 1751-1767. 41 RCTs, 2,672 participants. Corticosteroid injections reduced pain in the short term (e.g., lateral epicondylalgia SMD 1.44 vs no intervention), but the effect reversed at intermediate (26 weeks) and long term (52 weeks), when no intervention was favoured. One serious adverse event (tendon rupture) among 991 injected participants. For Achilles tendinopathy, polidocanol, aprotinin and platelet-rich plasma were not more effective than placebo (abstract, PMID 20970844). 10.1016/S0140-6736(10)61160-9