Effect of Isometric Exercise on Pain Perception in Rotator Cuff Related Shoulder Pain

Study Overview
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Brief Summary
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The aim of this study is to compare the immediate effects of an acute bout of isometric exercise of the shoulder external rotator muscles above and below pain threshold on pain intensity, pain threshold, conditioned pain modulation and pain free force in external rotation. To evaluate the results of the exercise, the subjects will be assessed at pre-intervention, immediately post-intervention and after and 45 minutes after each experimental condition.

Detailed Description
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The aim of this study is to compare the immediate effects of an acute bout of isometric exercise of the shoulder external rotator muscles above and below pain threshold on pain intensity, pain threshold, conditioned pain modulation and pain free force in external rotation. It will consist of a randomized three-treatment parallel-design study. The sample will consist of subjects with rotator cuff related shoulder pain (RCRSP). Once the sample is selected, subjects will participate in three experimental sessions, which will occur in a randomized order: two exercise sessions (supra-threshold and infra-threshold isometric exercise) and one control session. In the first session, information regarding clinical and demographical aspects will be collected. A washout period of approximately 48 hours will separate each of the experimental sessions. To evaluate the results of the exercise, the subjects will be assessed at pre-intervention, immediately post-intervention and 45 minutes after each experimental condition. Pain intensity, Pressure Pain Thresholds (PPT), Conditioned Pain Modulation (CPM), maximal voluntary isometric contraction (MVIC) and pain free isometric strength (PFIS) will be measured.

Official Title
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Effect of Isometric Exercise on Pain Perception in Subjects With Rotator Cuff Related Shoulder Pain

Conditions
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Rotator Cuff Tendinitis

Intervention / Treatment
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* Other: Supra-threshold isometric exercise
* Other: Infra-threshold isometric exercise


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: aged 18-80 years (likelihood of patients > 80 having degenerative changes in the shoulder is increased) pain localised to the proximal anterolateral shoulder region positive for pain on at least one of the following three impingement tests: Hawkins-Kennedy, Neer's, Jobe's positive for pain on resisted external rotation and/or abduction. Exclusion Criteria: shoulder surgery within last 6 months reasons to suspect systemic pathology including inflammatory disorders, cervical repeated movement testing affects shoulder pain and/or range of movement, passive external rotation deficit greater (less than 30º or a range of motion reduction of 50% or more as compared to the contralateral side), upper limb tension test A for cervical radiculopathy atraumatic degenerative rotator cuff tear based on the cluster of clinical tests (painful arc, drop arm test, and marked weakness into ER all three positive)

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Supra-threshold isometric exercise<br>Participants will perform 10 isometric external rotation supra-threshold contractions of the affected shoulder, each held for 15 seconds, with resting intervals of 15 seconds between contractions. | Other: Supra-threshold isometric exercise<br>* The supra-threshold intensity will be stablished at 120% of participant's PFIS pre-session measurement (20% above the individual's pain threshold).<br>|
| Experimental: Infra-threshold isometric exercise<br>Participants will perform 10 isometric external rotation infra-threshold contractions of the affected shoulder, each held for 15 seconds, with resting intervals of 15 seconds between contractions. | Other: Infra-threshold isometric exercise<br>* The infra-threshold intensity will be stablished at 80% of participant's PFIS pre-session measurement (20% bellow the individual's pain threshold).<br>|
| No Intervention: Control<br>Participants will remain resting. | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Pain intensity | Shoulder pain intensity reported by the patient will be assessed using a 100-mm visual analogue scale (VAS, 0-100, 0=minimum score, 100=maximum score). Higher values represent a better outcome (less pain). | Baseline | 
| Pain intensity | Shoulder pain intensity reported by the patient will be assessed using a 100-mm visual analogue scale (VAS, 0-100, 0=minimum score, 100=maximum score). Higher values represent a better outcome (less pain). | Immediately post-intervention | 
| Pain intensity | Shoulder pain intensity reported by the patient will be assessed using a 100-mm visual analogue scale (VAS, 0-100, 0=minimum score, 100=maximum score). Lower values represent a better outcome (less pain). | 45 minutes post-intervention | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Pressure Pain Thresholds (PPT) | PPTs will be recorded using an electronic algometer at the ipsilateral m. infraspinatus, the contralateral resting m. infraspinatus and the contralateral resting m. quadriceps. Higher values represent a better outcome. | Baseline, immediately post-intervention and 45 minutes post-intervention | 
| Pressure Pain Thresholds (PPT) | PPTs will be recorded using an electronic algometer at the ipsilateral m. infraspinatus, the contralateral resting m. infraspinatus and the contralateral resting m. quadriceps. Higher values represent a better outcome. | Immediately post-intervention | 
| Pressure Pain Thresholds (PPT) | PPTs will be recorded using an electronic algometer at the ipsilateral m. infraspinatus, the contralateral resting m. infraspinatus and the contralateral resting m. quadriceps. Higher values represent a better outcome. | 45 minutes post-intervention | 
| Conditioned pain modulation (CPM) | CPM will be tested using the upper extremity submaximal effort tourniquet test. | Baseline | 
| Conditioned pain modulation (CPM) | CPM will be tested using the upper extremity submaximal effort tourniquet test. | Immediately post-intervention | 
| Conditioned pain modulation (CPM) | CPM will be tested using the upper extremity submaximal effort tourniquet test. | 45 minutes post-intervention | 
| Maximal voluntary isometric contraction (MVIC) | MVIC will be measured at both m. infraspinatus and m. quadriceps of the non-affected side using a digital force gauge. | Baseline | 
| Maximal voluntary isometric contraction (MVIC) | MVIC will be measured at both m. infraspinatus and m. quadriceps of the non-affected side using a digital force gauge. | Immediately post-intervention and 45 minutes post-intervention | 
| Maximal voluntary isometric contraction (MVIC) | MVIC will be measured at both m. infraspinatus and m. quadriceps of the non-affected side using a digital force gauge. | 45 minutes post-intervention | 
| Pain free isometric strength/threshold (PFIS) | PFIS will be assessed at m. infraspinatus of the affected shoulder | Baseline | 
| Pain free isometric strength/threshold (PFIS) | PFIS will be assessed at m. infraspinatus of the affected shoulder | Immediately post-intervention | 
| Pain free isometric strength/threshold (PFIS) | PFIS will be assessed at m. infraspinatus of the affected shoulder | 45 minutes post-intervention | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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isometric exercise, rotator cuff, pain threshold