The most useful number in the Achilles literature is not how much pain came down. It is how quickly.
The trial
A randomized, placebo-controlled trial in the American Journal of Sports Medicine took 52 recreational athletes with chronic Achilles tendinopathy and gave everyone the same twelve-week eccentric loading programme. Half also received low-level laser therapy — 820 nm, twelve sessions over eight weeks, six points along the tendon, 5.4 J per session. Half received an identical placebo laser.
Pain during physical activity, on a 100 mm scale:
- 4 weeks — 53.6 mm with laser, 71.5 mm with placebo (P = .0003)
- 8 weeks — 37.3 mm versus 62.8 mm (P = .0002)
- 12 weeks — 33.0 mm versus 53.0 mm (P = .007)
Morning stiffness, ankle dorsiflexion, tenderness on palpation and crepitation all moved the same way.
The part worth noticing
Line the numbers up and the pattern is about time. The laser group at 4 weeks was roughly where the placebo group arrived at 12 weeks. Eight weeks of difference, on the measure patients care about, during the exact window when people decide whether to keep going.
That matters because eccentric loading is a demanding programme — 180 repetitions a day, every day, for three months — and its benefit arrives slowly. Most failures are not failures of the exercise. They are people stopping in week five. An adjunct that makes weeks two to six more tolerable is addressing the actual reason plans fall apart. We set out the programme itself in The Eccentric Loading Program, Explained.
Being precise about it
This is one randomized trial of 52 recreational athletes using one specific set of treatment parameters, and both groups did the loading programme — so the exercise is doing the structural work in each arm, and what the light changed was how fast the improvement came. The authors’ own conclusion was that it accelerated clinical recovery when added to the exercise regimen. We use it that way: as an adjunct with a defined job alongside loading, footwear and load management, not as a substitute for any of them. Photobiomodulation is not FDA-cleared for the treatment of Achilles tendinopathy.
If your heel has been stiff every morning for more than a few weeks, the first step is confirming which kind of Achilles pain it is, because midportion and insertional need different exercise ranges — that is in Achilles Tendon Pain: Making the Exercise Possible.
Reference
Stergioulas A, Stergioula M, Aarskog R, Lopes-Martins RAB, Bjordal JM. Effects of low-level laser therapy and eccentric exercises in the treatment of recreational athletes with chronic achilles tendinopathy. The American Journal of Sports Medicine. 2008;36(5):881–887. PMID 18272794. doi:10.1177/0363546507312165 Citation retrieved from PubMed.
This article is general education, not medical advice, and it is not a substitute for evaluation by a qualified clinician. It does not establish a physician–patient relationship. Individual results vary, and the studies described report group averages rather than what any one person should expect. Treatments discussed may not be FDA-cleared or approved for the conditions mentioned; where that is the case it is stated in the text. Talk to your own physician before starting, stopping or changing any treatment.
