Age-related Changes of Shoulder Muscles

Study Overview
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Brief Summary
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A cross-sectional descriptive study, in which the surface electromyographic activity of five shoulder muscles was compared in three populations: older adults, middle-aged adults and young adults. The evaluation of the electromyographic data offers a suitable foundation to understand aging process. This supports that surface electromyography provide information about the aged shoulder muscles. Loss of functionality is suffered by a high percentage of older adults, which greatly limits their physical activity. In this sense, this paper presents findings that might be related with possible therapeutic approaches in subsequent studies.

Detailed Description
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The purpose of the present work was to assess neuromotor abnormalities in aging shoulder. Twenty young adults (20-42), 20 middle-aged adults (43-67) and 20older adults (>68) were recruited. A comparative electromyography (EMG) study was performed on the upper and lower trapezius, middle deltoid, infraspinatus and serratus anterior. The EMG measurement (root mean square (RMS)) and onset time of isometric contractions were analyzed. Body mass index and strength were also tested.

Official Title
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Age-related Changes in Activation Patterns of Shoulder Muscles

Conditions
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Electromyography

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Healthy subjects with no previously manifested symptoms in the shoulder joint and/or the neck during the past year, Exclusion Criteria: moderate or severe cognitive impairment, rheumatologic diseases, massive osteoarthritis, tumors, shoulder joint instability, circulatory disorders (hemophilia clotting problems) and dermatological problems exacerbated by contact with skin

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 90 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Group I: Older adults<br>healthy subjects older than 68 years old whose shoulder muscle are measured by surface electromyography | |
| Group II: Adults<br>healthy subjects 43 to 67 years old, whose shoulder muscle are measured by surface electromyography | |
| Group III: Young adults<br>healthy subjects 20 to 42 years old, whose shoulder muscle are measured by surface electromyography | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The mean Root Mean Square (RMS) value | The electromyographic data were captured simultaneously on a PC by using the LabChart® software. Within the time interval from 2 to 4 seconds after contraction initiation a power spectrum analysis was performed together with the determination of RMS values. The mean RMS values were automatically obtained from the software | 30 minutes | 
| onset latency | Start of contraction on the basis of 15% of RMS | 30 minutes | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| maximal isometric voluntary contraction | Using hand-held dynamometer | 5 minutes | 
| body mass index |  | 5 minutes |