Tolerance and effectiveness of eccentric vs. concentric muscle strengthening in rotator cuff partial tears and moderate to severe shoulder pain. A randomized pilot study

Abstract

Introduction: Rotator cuff tears are the main cause of shoulder pain and disability. First line of treatment is conservative; there is evidence regarding the advantage of using eccentric over concentric exercises in tendinopathies, but there are no evidence-based recommendations on starting strengthening exercise during painful phases nor on the effectiveness and advantages of eccentric vs. concentric exercise in rotator cuff tears.

Objective: To evaluate the tolerance of a resistance strengthening program and to compare eccentric vs. concentric programs.

Design: A pilot, experimental, randomized controlled study.

Setting: Outpatient Rehabilitation Center.

Patients: Twenty-six patients with a diagnosis of partial rotator cuff tear were randomly assigned to: the experimental group (eccentric, n = 12) and the control (concentric, n = 14).

Intervention: The experimental group performed muscle strengthening with eccentric technique directed to shoulder and scapular girdle muscles, while the control group performed the concentric technique.

Main outcome measures: Visual Analogue Scale (VAS), Constant Scale, Strength, Structure (Ultrasound report).

Results: The tolerance rate was 96% in both groups. Median age (experimental vs. control) was 54.5 vs. 54 years (p = 0.69). Results at baseline, and at months 1, 3, and 12 (median) were as follows: for VAS (mm), experimental: 55, 30, 30, and 10, p < 0.001 (intra-group); control: 50, 30, 30, and 5, p = 0.01; Constant scale (points): experimental 58.5, 88, 93, and 85, p < 0.001; control 50.62, 80, and 91.5, p = 0.038; normalized strength (Kg); experimental: 0.23, 0.29, 0.73, and 0.72, p = 0.001, and control: 0.24, 0.21, 0.54, and 0.66, p = 0.01. We found inter-group differences in the Constant scale at 1 and 3 months (p < 0.05), and in strength at months 1 and 3 (p < 0.05). We observed structural differences in tendon (healing) between groups at 3 and 12 months.

Conclusions: Eccentric and concentric strengthening were well tolerated; both show early improvement in pain, functionality and tendon structure. Eccentric training appears to be more effective than concentric in the early improvement of functionality, strength and tendon healing.

Keywords: Rehabilitation; Resistance training; Rotator cuff; Shoulder pain; Tendinopathies.

Conflict of interest statement

All authors declare not having any conflict of interest. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

© 2020 Delhi Orthopedic Association. All rights reserved.

Figures

Fig. 1

Assisted Muscle stretching. a). Biceps and anterior capsule. b). Triceps. c). Posterior capsule. d). Pectoralis.

Fig. 2

Eccentric training technique with the patient laid down. a). Anterior deltoid contraction. b). External rotators contraction. c). Internal rotators contraction. d). Lateral deltoid contraction.