Research Review by Dr. Shawn Thistle©

Date:

June 2008

Study Title:

Effects of low-level laser therapy and eccentric exercise in the treatment of recreational athletes with chronic Achilles tendinopathy

Authors:

Stergioulas A et al.
Authors’ Affiliations: Faculty of Human Movement and Quality of Life, Peloponnese University, Sparta, Greece.

Publication Information:

American Journal of Sports Medicine 2008; 36(5): 881-887.

Summary:

Tendinopathy is a common affliction for athletes at all levels of competition, which can vary in clinical presentation. It is well established that inflammation in the acute phase of tendon damage diminishes quickly (within days), giving way to a complex pathophysiological cascade of structural degeneration involving the collagen matrix of the tendon, as well as cell apoptosis, intratendinous neovasularization, partial rupture, and increased concentrations of neuropeptides. The end result, if left untreated, can be tendon degeneration, pain, loss of performance, and eventually tendon rupture.

Although the literature as a whole suggests that eccentric exercise is an effective treatment for tendinopathy (particularly chronic cases), it is by no means conclusive at this point. Eccentric exercise (EE) interventions are generally long (8-12 weeks), induce transient pain or discomfort, and may be best implemented with adjunctive interventions. This study investigated whether the addition of low-level laser therapy (LLLT) to an EE program for the first 8 weeks would speed recovery and improve outcomes in recreational athletes with chronic Achilles tendinopathy.

52 recreational athletes were included in the study, all meeting the following inclusion criteria:
  • at least 6 months of unilateral, painful, activity-limiting symptoms from the Achilles tendon region
  • pain localized to the Achilles tendon, 2-6 cm proximal to its insertion on the calcaneous
  • crepitation and tenderness during palpation
  • a single local thickening of the tendon (< 4 cm in size), and structural degeneration of tendon fibers identified by diagnostic ultrasound
  • restricted ROM with < 10°of dorsiflexion measured by goniometry
Subjects were excluded if they had received oral or injected steroids within the previous 26 weeks, had symptoms for < 6 months, or had systemic inflammatory arthritis or hypercholesterolemia.

Subjects were randomized into 2 groups:
  1. EE and LLLT:EE program described below plus LLLT with the following parameters:
    • wavelength: 820 nm
    • optical output: 30 mW
    • irradiation area: 0.5 cm2
    • power density: 60 mW/cm2
    • number of irradiation points: 6
    • energy per point per session: 0.9 J
    • total energy in 12 sessions: (6 x 0.9 x 12) = 64.8 J
    • treatment schedule: 2x/wk for 4 weeks, 1x/week for 4 weeks
  2. EE and placebo LLLT: EE program described below plus placebo laser treatment
Eccentric Exercise Program:
  • performed 4x/week for 8 weeks in a supervised environment
  • exercise begins with bodyweight only, progressing in 4 Kg increments (loaded in a backpack) as tolerated
  • eccentric, unilateral calf raises were performed on a step with the knee straight
  • 12 sets of 12 repetitions (1 minute rest between sets) were repeated 4 days per week for 8 weeks – the program began with 1 set of 15 reps and progressed as tolerated
  • subjects are informed to continue exercise through mild pain (< 50 mm on a 100 mm Visual Analogue Scale), but were told to stop if pain was disabling, or lasted into the next day
  • in addition to the EE, all subjects performed static stretching of the gastrocnemius and soleus
Outcomes were measured at 0, 4, 8, and 12 weeks, and included pain intensity during activity, morning stiffness, crepitation, and tenderness (all measured with a 100 mm VAS); as well as dorsiflexion ROM.

Pertinent results of this study include:
  • the 2 groups were comparable in age, symptoms, and stature (all were recreational athletes participating in activities 1-5 times per week)
  • 12 patients (6 in each group) withdrew from the study due to lack of effect at the 4 week mark
  • all other subjects (n=40) completed all 12 sessions of true or placebo LLLT, and there was a compliance rate of 85-100% with the EE regimen
  • pain intensity during physical activity was significantly better in the true LLLT group at 4, 8, and 12 weeks post-randomization (at 12 weeks, laser group reduced VAS score from ~80 mm to ~30 mm)
  • all secondary outcomes were significantly better in the true LLLT group (p < 0.05) than the placebo LLLT group at 4, 8, and 12 weeks
  • four patients reported minor or moderate aching in the calf with the EE (note: no patients had to cease the program)

Conclusions & Practical Application:

Chronic Achilles tendinopathy can be a difficult condition to manage, and reported treatment outcomes in the literature have generally been poor. EE regimens have shown promise, particularly in chronic cases such as those included in this study (the inclusion criteria are a strength of this paper, as they ensured a group of difficult cases).

This study provides preliminary evidence that adding LLLT to an EE program may indeed speed recovery and improve outcomes. Further, these benefits may be maintained for up to four weeks after treatment. Future studies should include larger patient groups, and longer follow-up periods. Further, the applicability of this approach in more elite athletes needs to be investigated.