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.

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.

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

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.