Isometric exercises do not provide immediate pain relief in Achilles tendinopathy: A quasi-randomized clinical trial

Abstract

Background: Isometric exercises may provide an immediate analgesic effect in patients with lower-limb tendinopathy and have been proposed as initial treatment and for immediate pain relief. Current evidence is conflicting, and previous studies were small.

Objective: To study whether isometric exercises result in an immediate analgesic effect in patients with chronic midportion Achilles tendinopathy.

Methods: Patients with clinically diagnosed chronic midportion Achilles tendinopathy were quasi-randomized to one of four arms: isometric calf-muscle exercises (tiptoes), isometric calf-muscle exercises (dorsiflexed ankle position), isotonic calf-muscle exercises, or rest. The primary outcome was pain measured on a visual analogue scale (VAS) score (0-100) during a functional task (10 unilateral hops) both before and after the intervention. Between-group differences were analyzed using a generalized estimation equations model.

Results: We included 91 patients. There was no significant reduction in pain on the 10 hop test after performing any of the four interventions: isometric (tiptoes) group 0.2, 95%CI -11.2 to 11.5; isometric (dorsiflexed) group -1.9, 95%CI -13.6 to 9.7; isotonic group 1.4, 95%CI -8.3 to 11.1; and rest group 7.2, 95%CI -2.4 to 16.7. There were also no between-group differences after the interventions.

Conclusion: The isometric exercises investigated in this study did not result in immediate analgesic benefit in patients with chronic midportion Achilles tendinopathy. We do not recommend isometric exercises if the aim is providing immediate pain relief. Future research should focus on the use of isometric or isotonic exercise therapy as initial treatment as all exercise protocols used in this study were well-tolerated.

Keywords: loading; pain management; rehabilitation; tendon.

Figure 1

CONSORT flow diagram demonstrating the flow of patients through the study

Figure 2

Individual patient data and means per intervention arm (A‐D) for the patient‐reported pain (visual analogue scale [VAS] score) immediately after performing 10 unilateral hops. VAS scores were assessed before (pre) and immediately after the intervention (post). The gray lines represent the individual VAS scores and the black line the raw mean VAS scores of the intervention arm. No statistically significant differences between the four intervention arms were found. A clinical relevant immediate analgesic effect of 20 points was detected in six patients (25%) in the isometric (tiptoes) group, 3 patients (17%) in the isometric (dorsiflexed) group, four patients (17%) in the isotonic group, and 1 patient (4%) rest group