Study: Resistance as Effective as Eccentric Training for Achilles Tendinopathy

The effectiveness of a loading regimen for treatment of Achilles tendinopathy is well-established, and when it comes to what kind of regimen to use—eccentric training (ECC) or heavy resistance training (HSR)—researchers were surprised to find that both work equally well.

In a study published in the May 27 issue of The American Journal of Sports Medicine researchers from Denmark compared ECC and HSR interventions among 58 patients with chronic Achilles tendinopathy and found that both approaches "yield positive, equally good, lasting clinical results." Authors had hypothesized that the HSR group would yield better outcomes, based on similar studies conducted on patients with patellar tendinopathy.

For the Achilles study, patients were divided into 2 groups, with 30 receiving HSR and the remaining 28 receiving ECC. Evaluations were conducted at baseline, 12 weeks, and 52 weeks, and included the Victorian Institute of Sports Assessment for Achilles (VISA-A), pain level assessments, ultrasonography, color Doppler scans, and patient satisfaction ratings.

The ECC group was assigned a regimen of 3 sets of 15 slow repetitions of eccentric unilateral loading while standing on the step of a staircase, 1 exercise performed with straight knees and 1 with bent knees twice a day, 7 days a week, for 12 consecutive weeks. The HSR regimen was performed 3 times a week using resistance equipment at a fitness center, and consisted of 3 2-legged exercises: heel rises with bended knee in a seated calf raise machine, heel rises with straight knee in the leg press machine, and heel rises with straight knee standing on a disc weight with the forefoot with barbells on shoulders. HSR participants completed "3 or 4" sets in each exercise, with reps decreasing and loads increasing over time. Physical therapists instructed both sets of patients on how to perform the exercises.

"The main difference between the 2 exercises regimens is the total loading time 'seen' by the tendon and the calculated session," authors write. "The time of tendon loading was estimated to be approximately 63 min/wk for ECC and 41 min/wk for HSR."

What researchers found was that both approaches resulted in "robust clinical and structural improvements" for patients, with average VISA-A improvements of 10 points or more (on a 100-point scale) and reductions of 30 points or more in pain while running. These improvements remained equal at the 12-week and 52-week marks.

Researchers did identify a few minor differences between the groups: HSR participants reported higher patient satisfaction at 12 weeks (though that dropped off at 52 weeks), and compliance rates were lower for ECC (78%) compared with HSR (92%). Authors are unsure of the exact reason for the difference in compliance, but they speculate that the longer time commitments required by ECC could explain at least part of the differences—"one aspect that may be considered when loading regimens are offered to patients," they write.

"Eccentric loading regimens for tendinopathy have been widely accepted as the treatment of choice," authors write. "Although the present study was not designed to answer the effect of [contraction regimens such as HSR] per se, it appears that HSR, which includes a concentric as well as eccentric component, produced similar results to the traditional ECC regimen."