To determine the efficacy of concentric vs. eccentric exercise in improving shoulder function, pain, and tendon characteristics for patients with rheumatoid arthritis and rotator cuff tendinopathy.
Forty patients with rheumatoid arthritis and rotator cuff tendinopathy were divided into either concentric or eccentric exercise groups, with 20 patients in each group. Patients received 12 sessions at a pace of 3 sessions per week. Shoulder Pain and Disability Index (SPADI), the visual analogue scale (VAS), supraspinatus and subscapularis thickness, echo pixels, and the Disease Activity Score-28-erythrocyte sedimentation rate (DAS-28-ESR) were assessed at baseline and post-treatment.
There was a significant difference between the concentric and eccentric groups regarding SPADI and VAS scores in favor of the eccentric group. However, there was no significant difference between the two groups regarding tendon thickness, echo pixels, or DAS-28-ESR.
Eccentric exercises were more effective than concentric exercises in improving shoulder function and pain intensity. However, neither of the two types of exercises was superior in improving tendon characteristics or disease activity.
Rheumatoid arthritis (RA) is a chronic systemic inflammatory autoimmune disease that affects 0.5% of the general population and causes bone and cartilage destruction [
The shoulder joint is a common site of musculoskeletal pain in the general population, which was reported to affect between 7% and 27% of the population [
Patients with RA face the added risk of impaired shoulder function due to inflammation. Synovitis, bursitis, and tendinitis can cause decreased muscle strength, persistent pain, decreased range of motion, and joint destruction, resulting in functional loss and difficulties with daily activities [
Resistance training is commonly utilized to increase muscular strength, thus improving athletic performance, preventing injuries, and maintaining a healthy lifestyle [
Consequently, this randomized comparative study aimed to determine the efficacy of concentric vs. eccentric exercise in improving shoulder function, pain, and tendon characteristics for rotator cuff tendinopathy in patients with RA.
This randomized comparative study was carried out between September 2021 and August 2022. This study was approved by the Institutional Review Board of the Faculty of Physical Therapy, Cairo University (P.T.REC/012/003375). Informed consent to publish this study was obtained from the patients. In addition, this study was registered at the National Institutes of Health (clinicaltrials.gov) with a registration number of NCT05054920.
Fifty-eight adult patients with RA based on the 2010 American College of Rheumatology/European League Against Rheumatism classification criteria were screened [
Tendinopathy was graded as follows [
Grade 0=normal tendon with average thickness and preserved fibrillar pattern.
Grade 1=reactive tendinopathy; the tendon is focally or diffusely swollen with diffuse hypoechogenicity.
Grade 2=tendon disrepair, with the same findings in grade 1 in addition to focal areas of hypoechogenicity and a lost fibrillar pattern.
Grade 3=degenerative tendinopathy, the same as grade 2 with more extensive lesions.
The sample size was calculated using G*Power 3.1 (Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany), assuming α (two-sided)=0.05 and 1-β=0.80, as observed in a previous study. The sample size was determined to be 34. We added six more to account for any dropouts that may occur. As a result, the study’s total sample size was 40 patients [
It is a self-reported questionnaire that assesses shoulder function. It is divided into two domains. The first domain assesses pain, while the second assesses shoulder disability. The patient answered each question by selecting a number from 0 to 10, with 0 indicating no pain or difficulty and 10 indicating the worst pain or so difficult that requires help. The total score was computed and divided by 130 to obtain a percentage. Therefore, Shoulder Pain and Disability Index (SPADI) is a valid and reliable tool for evaluating patients with rotator cuff tears and RA. The minimal clinically important difference (MCID) ranges between 8 and 13. Furthermore, it is validated in Arabic [
The visual analogue scale (VAS) was used to assess current pain. It consists of a 10 cm line labeled “0” at one end, indicating no pain, and a maximum of “10” at the other, indicating the worst pain. VAS is a valid and reliable method for chronic pain assessment. The MCID for rotator cuff pathology is 1.4 cm [
Shoulder MSUS was used to assess the supraspinatus tendon (in the modified Crass position) using a LOGIQ-P6 machine (GE Healthcare, Chicago, IL, USA) equipped with a high-frequency broadband linear array transducer at 10–13 MHz. MSUS was carried out by one operator who was blind to the physiotherapy protocol. The supraspinatus tendon thickness was measured in short axis view at 10, 15, and 20 mm lateral to the biceps tendon. The mean tendon thickness of the three measurements was calculated. The tendon echogenicity was determined by grayscale analysis of stored images using the standard histogram function in Adobe Photoshop (Adobe, San Jose, CA, USA). A region of interest of the entire tendon was defined using the freehand selection option to ensure that the overlying subacromial subdeltoid bursa, underlying cartilage, and bone were not involved [
(1) Subscapularis tendon thickness and echo pixels
The same operator operated the LOGIQ-P6 machine mentioned above to measure the subscapularis tendon in the long-axis view to the attachment at the lesser tuberosity. Again, the tendon echo pixels were calculated similarly to the supraspinatus [
(2) Disease Activity Score-28-erythrocyte sedimentation rate
A single physician, blind to the physiotherapy protocol, calculated the Disease Activity Score-28-erythrocyte sedimentation rate (DAS-28-ESR) score for all patients. It is an index based on the number of tenders, swollen joints, and ESR. It is a valid and reliable method for assessing disease activity in patients with RA [
A single therapist carried out the physiotherapy protocol for the two groups. A single physician, blind to all interventions and patient groupings, carried out the MSUS examination and calculated the DAS-28-ESR. The study’s goal and procedures were discussed with the patients. Patients were asked to sign an informed consent form if they agreed to participate in the study. Patients received 12 sessions at a pace of three sessions per week. All outcome measures were measured at baseline and after 12 sessions.
Both groups performed the pectoralis minor stretch using an active corner stretch with the patient in a standing position [
All exercises were performed with the patient standing. Elastic resistance bands were used for the exercises, with the level of resistance based on the patient’s tolerance. Furthermore, each patient completed three sets of each exercise. Each set was composed of 10 repetitions of each exercise.
(1) Internal and external rotation exercises
Elastic resistance was attached to the wall bar, and the patient was instructed to move her forearm towards or away from her body (
(2) Abductor strengthening
The patient was instructed to raise his arm to 90° in the scapular plane against elastic band resistance (
(1) Internal and external rotation exercises
Patients were positioned at the end of the internal or external rotation range with elastic resistance in tension. The patient was instructed to gradually control the relaxation of the elastic resistance while slowly returning to the neutral position [
(2) Abductor strengthening
The patient’s arm was passively elevated to 90° in the scapular plane, and the patient was instructed to gradually control the relaxation of the elastic resistance while gradually lowering the arm to the 0° position [
Data were coded using the IBM SPSS Statistics version 28 (IBM Corp., Armonk, NY, USA). Data were summarized in the form of mean and standard deviation for quantitative variables. For categorical variables, frequencies (number of cases) and relative frequencies (percentages) were used.
Comparisons between groups were performed using unpaired t-tests for normally distributed quantitative variables. On the other hand, a non-parametric Mann–Whitney U-test was used for non-normally distributed quantitative variables. Comparing pre- and post-treatment in each group was conducted using paired t-tests in normally distributed quantitative variables. In contrast, the non-parametric Wilcoxon signed-rank test was used for nonnormally distributed quantitative variables. p-values less than 0.05 were considered statistically significant.
Forty adult patients with RA and rotator cuff tendinopathy were enrolled in the study and completed baseline and follow-up assessments. Each group consisted of 20 patients. Group 1 received concentric exercise sessions. At the same time, group 2 received eccentric exercise sessions.
Patients had a mean age of 44.43±5.39 years and a mean RA disease duration of 5.83±3.86 years. There was no statistically significant difference between the two groups regarding age, sex, disease duration, tendinopathy stage, or disease activity (
There was a statistically significant decrease in SPADI scores post-treatment in both groups compared to baseline assessment (p<0.001;
There was a statistically significant decrease in VAS scores post-treatment in both groups compared to baseline assessment (p<0.001;
There was no statistically significant change in supraspinatus tendon thickness post-treatment in either group. There was no statistically significant difference between the two groups, either at baseline or post-treatment.
There was a statistically significant increase in echo pixels of the supraspinatus tendon in the eccentric group only post-treatment compared to baseline (p=0.020). However, there was no statistically significant difference between the two groups either at baseline or post-treatment (
There was a statistically significant decrease in subscapularis tendon thickness in the concentric exercise group only post-treatment compared to baseline (p=0.027). However, there was no difference between the two groups either at baseline or post-treatment (
There was a significant increase in echo pixels of the subscapularis tendon in the concentric group only post-treatment compared to baseline (p=0.027). However, there was no difference between the two groups either at baseline or post-treatment (
There was a statistically significant decrease in DAS-28-ESR scores post-treatment in both groups compared to baseline assessment (p<0.001;
Rheumatoid affections of the shoulder joints frequently occur in patients with RA [
Exercise has proven its efficacy in restoring function in patients with rotator cuff tendinopathy. Literature has shown progressive loading exercises’ effectiveness in treating rotator cuff tendinopathy patients. Among the exercises used in treating patients with rotator cuff tendinopathy are concentric and eccentric exercises [
In this study, shoulder function measured by the SPADI and pain measured by the VAS improved in both groups. Besides, the improvement was greater than the MCID. Moreover, there was a significant improvement in shoulder function and pain in the eccentric group compared to the concentric group. Furthermore, the difference between the two groups was greater than the MCID.
This was in agreement with the results of Chaconas et al. [
To the best of author’s knowledge, this is the first randomized clinical trial to compare concentric vs. eccentric exercises in patients with RA. Exercise improved the pain and function of shoulder tendinopathy in patients with RA, with better outcomes in the eccentric group. This agrees with many studies on non-RA patients that found an eccentric exercise more beneficial than a concentric exercise in improving pain, insulin sensitivity, glycemic control, blood lipid profile, and physical fitness in healthy people [
MSUS was used to evaluate shoulder tendinopathy and the efficacy of the exercise regimen in this study. This study showed no difference between the two groups regarding supraspinatus tendon or subscapularis tendon thickness at baseline or post-treatment. Furthermore, only the concentric group showed a decrease in tendon thickness of the subscapularis tendon post-treatment compared to baseline.
Tendon thickening may be the first pathological manifestation of tendinopathy. The thicker tendon will occupy a larger space within the subacromial space, thus, leading to tendon compression [
Echo pixels analysis evaluates the pixel-intensity distribution in the tendons, where echo pixels are inversely proportional to tendon affection. Compared to normal tendons, decreased echo pixels were observed in tendinopathy [
However, there was no difference between the two groups regarding any tendon characteristics. The concentric exercise was beneficial in improving subscapularis tendon characteristics. At the same time, eccentric exercise improved supraspinatus tendon characteristics. This may be due to the different anatomical backgrounds, physiology, and mechanisms of action. The subscapularis muscle is the only rotator cuff muscle inserted in the lesser tuberosity and acts as an internal shoulder rotator. Supraspinatus, infraspinatus, and teres minor are inserted into the greater tubercle and act as external rotators or abductors [
The DAS-28-ESR indicates RA disease activity, with a higher score indicating higher disease activity [
This study has some limitations, such as the lack of a control group and the possibility that a longer duration of treatment may be needed before changes in tendon characteristics can be compared. Moreover, muscle power was not assessed. Furthermore, we included patients with subscapularis and supraspinatus tendinopathies. However, this was the first study comparing eccentric and concentric exercises in patients with RA. We recommend further studies with an extended exercise program on a large scale of patients and research involving the response of different rotator cuff tendons to different exercises. Additionally, we suggest a study involving a control group.
This study has concluded that eccentric exercise is more effective than concentric exercise in improving pain and function in rotator cuff tendinopathy in patients with RA. However, there was no difference between the types of exercises related to any of the MSUS findings.
No potential conflict of interest relevant to this article was reported.
None.
Conceptualization: Wahba MM, Abdelsalam MS, Hegazy MM. Methodology: Wahba MM, Abdelsalam MS, Elgohary R, Selim M. Formal analysis: Wahba MM, Elgohary R, Abdelsalam MS. Project administration: Abdelsalam MS, Selim M. Visualization: Wahba MM, Selim M, Elgohary R, Hegazy MM. Writing – original draft: Wahba MM, Selim M. Writing – review and editing: Wahba MM, Abdelsalam MS, Selim M, Hegazy MM. Approval of final manuscript: all authors.
Study flowchart.
Internal and external rotation exercise (A) starting position for external rotation, (B) end position of external rotation, (C) starting position for internal rotation, and (D) end position of internal rotation.
Abductor strengthening (A) starting position for abduction and (B) end position of abduction.
Patients characteristics
Characteristic | Group 1 (n=20) | Group 2 (n=20) | p-value |
---|---|---|---|
Age (yr) | 45.20±5.26 | 43.65±5.54 | 0.370 |
Disease duration (yr) | 5.90±3.63 | 5.75±4.18 | 0.738 |
Sex | >0.999 | ||
Male | 3 | 2 | |
Female | 17 | 18 | |
Supraspinatus tendinopathy stage | >0.999 | ||
0 | 1 | 0 | |
1 | 9 | 10 | |
2 | 5 | 5 | |
3 | 5 | 5 | |
Subscapularis tendinopathy stage | 0.748 | ||
0 | 13 | 10 | |
1 | 6 | 9 | |
2 | 1 | 1 | |
3 | 0 | 0 |
Values are presented as mean±standard deviation or number only.
Comparison of SPADI, VAS, tendon characteristics, and DAS-28-ESR between and within groups
Variable | Group | Baseline | Post | MD | p-value |
---|---|---|---|---|---|
SPADI (%) | Group 1 | 70.5±15.4 | 44.8±19.6 | 25.7 | <0.001 |
Group 2 | 63.2±17.0 | 28.5±16.6 | 34.7 | <0.001 |
|
MD | 7.38 | 16.35 | - | - | |
p-value | 0.159 | 0.007 |
- | - | |
VAS (cm) | Group 1 | 7.12±2.25 | 3.74±2.24 | 3.38 | <0.001 |
Group 2 | 6.61±2.20 | 2.30±1.61 | 4.31 | <0.001 |
|
MD | 0.5 | 1.4 | - | - | |
p-value | 0.159 | 0.025 |
- | - | |
Supraspinatus thickness (mm) | Group 1 | 4.79±1.08 | 4.99±1.27 | -0.195 | 0.215 |
Group 2 | 4.46±0.86 | 4.52±0.96 | -0.060 | 0.648 | |
MD | 0.33 | 0.46 | - | - | |
p-value | 0.287 | 0.203 | - | - | |
Supraspinatus echo pixels | Group 1 | 27,828.95±7,874.38 | 28,410.95±6,211.56 | -582.00 | 0.476 |
Group 2 | 24,552.90±6,254.36 | 26,889.75±6,845.27 | -2,336.85 | 0.020 |
|
MD | 3,726.05 | 1,521.20 | - | - | |
p-value | 0.153 | 0.466 | - | - | |
Subscapularis thickness (mm) | Group 1 | 3.03±0.65 | 2.86±0.59 | 0.16 | 0.027 |
Group 2 | 3.01±0.80 | 2.99±0.63 | 0.03 | 0.712 | |
MD | 0.01 | -0.12 | - | - | |
p-value | 0.966 | 0.532 | - | - | |
Subscapularis echo pixels | Group 1 | 17,536.90±4,325.39 | 19,355.40±5,342.39 | -1,516.05 | 0.027 |
Group 2 | 17,536.90±4,325.39 | 18,135.25±3,828.76 | -598.35 | 0.548 | |
MD | 302.45 | 1,220.00 | - | - | |
p-value | 0.838 | 0.412 | - | - | |
DAS-28-ESR | Group 1 | 4.45±0.83 | 3.28±0.99 | 1.17 | <0.001 |
Group 2 | 4.88±0.77 | 3.38±1.00 | 1.49 | <0.001 |
|
MD | -0.43 | -0.11 | - | - | |
p-value | 0.099 | 0.736 | - | - |
Values are presented as mean±standard deviation.
SPADI, Shoulder Pain and Disability Index; VAS, visual analogue scale; DAS-28-ESR, Disease Activity Score-28-erythrocyte sedimentation rate; MD, mean difference.
p<0.05,
p<0.01, and
p<0.001.