Age-related Differences in Shoulder Dynamic and Isometric Contractions

Age-related Differences in Motor Recruitment Patterns of the Shoulder in Dynamic and Isometric Contractions. A Cross-sectional Study

A cross-sectional descriptive study, in which the surface electromyographic activity of five shoulder muscles was compared in two populations: older adults and 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.

Study Overview

• Status: Completed
• Conditions: Electromyography
• Intervention / Treatment: Device: Surface Electromyography

Detailed Description

Aging processes in the musculoskeletal system lead to functional impairments that restrict participation. Purpose: To assess differences in force and motor recruitment patterns of shoulder muscles between age groups to understand functional disorders. A cross-sectional study comparing thirty adults (20-64) and 30 older adults (>65). Surface-electromyography (sEMG) of the middle deltoid, upper and lower trapezius, infraspinatus and serratus anterior muscles was recorded. Maximum isometric voluntary contraction (MIVC) was determined at 45° glenohumeral abduction. For the sEMG signal registration, concentric and excentric contraction with and without 1 kg and isometric contraction were requested. Participants abducted the arm from 0° up to an abduction angle of 135° for concentric and excentric contraction; and from 0º to 45º and remained there at 80% of the MIVC level while isometrically pushing against a handheld dynamometer. Differences in sEMG amplitudes (root mean square, RMS) of all contractions, but also onset latencies during concentric contraction of each muscle between age groups were analyzed. Statistical differences in strength (Adults>Older adults;0.05) existed between groups. No significant differences in RMS values of dynamic contractions were detected, except for serratus anterior, but there were for isometric contraction of all muscles analyzed (Adults>Older adults;0.05). The recruitment order varied between age groups, showing a general tendency towards delayed onset times in Older Adults, except for the upper trapezius muscle. Age differences in muscle recruitment patterns were found, which underscores the importance of developing musculoskeletal data to prevent and guide geriatric shoulder pathologies.

• Study Type: Observational
• Enrollment (Actual): 60

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 20 years and older (ADULT, OLDER_ADULT)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

• Sampling Method: Non-Probability Sample

Study Population

Participants came from Madrid and Castilla La Mancha (Spain) and voluntarily attended the Unit of the Research Group "Physical Therapy in Women´s Health Processes" in the Department of Physical Therapy, University of Alcalá, and the Ocaña Senior Center.

Description

Inclusion Criteria:

• Healthy subjects
• 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)
• Dermatological problems exacerbated by contact with skin.

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Older adults; Participants, without symptoms in the shoulder and / or cervical area (at least the last year), were assigned to the Older adult group: over 65 years.	Device: Surface Electromyography; SEMG was used to measure the amplitude and onset of five shoulder muscle electrical signal, performing glenohumeral abduction. In this movement, the middle deltoid muscle was selected because it is a main motor. The infraspinatus muscle represented the rotator cuff muscle group. The middle deltoid muscle was selected as the representative of shoulder abduction because it is a main motor in this movement. The trapezius muscle and the serratus anterior muscle were chosen as representative established of the ascending scapular rotator muscles.
Adults; Participants, without symptoms in the shoulder and / or cervical area (at least the last year), were assigned to the Adult groups: 20 to 64 years.	Device: Surface Electromyography; SEMG was used to measure the amplitude and onset of five shoulder muscle electrical signal, performing glenohumeral abduction. In this movement, the middle deltoid muscle was selected because it is a main motor. The infraspinatus muscle represented the rotator cuff muscle group. The middle deltoid muscle was selected as the representative of shoulder abduction because it is a main motor in this movement. The trapezius muscle and the serratus anterior muscle were chosen as representative established of the ascending scapular rotator muscles.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
The mean Root Mean Square (RMS) value	The electromyographic data were captured simultaneously on a computer 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.	day 1
onset muscle contraction	The onset was obtained as the time distance of the interception between the level of pre-activation relative to the onset of arm displacement during dynamic contraction and the linearly interpolated RMS slope	day 1

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Maximal isometric voluntary contraction	Using hand-held dynamometer	day 1
body mass index	is a measure of body fat based on height and weight that applies to adult men and women. Enter your weight and height using standard or metric measures.	day 1

Collaborators and Investigators

• Sponsor: University of Castilla-La Mancha
• Collaborators: University of Alcala
• Investigators: Principal Investigator: Cristina Lirio-Romero, PhD, University of Castilla-La Mancha

Publications and helpful links

General Publications

• Lirio-Romero C, Anders C, De La Villa-Polo P, Torres-Lacomba M. Implications on older women of age- and sex-related differences in activation patterns of shoulder muscles: A cross-sectional study. J Women Aging. 2019 Nov-Dec;31(6):492-512. doi: 10.1080/08952841.2018.1521654. Epub 2018 Sep 25.
• McManus L, De Vito G, Lowery MM. Analysis and Biophysics of Surface EMG for Physiotherapists and Kinesiologists: Toward a Common Language With Rehabilitation Engineers. Front Neurol. 2020 Oct 15;11:576729. doi: 10.3389/fneur.2020.576729. eCollection 2020.
• Medved V, Medved S, Kovac I. Critical Appraisal of Surface Electromyography (sEMG) as a Taught Subject and Clinical Tool in Medicine and Kinesiology. Front Neurol. 2020 Oct 26;11:560363. doi: 10.3389/fneur.2020.560363. eCollection 2020.

Study record dates

Study Major Dates

• Study Start: December 1, 2015
• Primary Completion (ACTUAL): January 1, 2019
• Study Completion (ACTUAL): March 1, 2019

Study Registration Dates

• First Submitted: January 9, 2021
• First Submitted That Met QC Criteria: January 11, 2021
• First Posted (ACTUAL): January 12, 2021

Study Record Updates

• Last Update Posted (ACTUAL): August 11, 2021
• Last Update Submitted That Met QC Criteria: August 3, 2021
• Last Verified: August 1, 2021

More Information

Terms related to this study

• Keywords: Musculoskeletal diseases; Shoulder muscles; Age groups
• Other Study ID Numbers: CLirio04

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No