Between-day reliability of a hand-held dynamometer and surface electromyography recordings during isometric submaximal contractions in different shoulder positions

• Published in: Journal of electromyography and kinesiology Vol. 24; no. 5; pp. 579 - 587
• Main Authors: Andersen, Kathrine S., Christensen, Birgitte H., Samani, Afshin, Madeleine, Pascal
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.10.2014
• Subjects: Absolute reliability; Adult; Electromyography - methods; Female; Hand; Humans; Isometric Contraction - physiology; m. Deltoideus anterior; m. Trapezius superior; Male; Muscle Strength; Muscle Strength Dynamometer; Muscle, Skeletal - physiology; Outcome measurements; Physical Examination; Physical Medicine and Rehabilitation; Range of Motion, Articular; Relative reliability; Reproducibility of Results; Rotation; Shoulder - physiology; Young Adult; m. Trapezius superior; Relative reliability; Absolute reliability; Outcome measurements; m. Deltoideus anterior
• ISSN: 1050-6411; 1873-5711; 1873-5711
• DOI: 10.1016/j.jelekin.2014.05.007

Functional shoulder assessments require the use of objective and reliable standardized outcome measures. Therefore, the aim of this study was to examine the between-day reliability of a hand-held dynamometer when measuring muscle strength during flexion, abduction, and internal and external rotation as well as surface electromyography (EMG) when measuring muscle activity from m. trapezius superior and deltoideus anterior. Twenty-four healthy subjects participated and performed four isometric contractions measured with a hand-held dynamometer and EMG. Both relative and absolute reliability were calculated based on the mean of the last three of the four repetitions. EMG amplitude was assessed calculating both absolute and normalized root-mean-square (RMS) values. The reliability of the hand-held dynamometer was high (LOA=3.2–7.6% and ICC=0.89–0.98). The absolute reliability for EMG showed similar results for absolute RMS values (LOA=20.0–68.4%) and normalized RMS values (LOA=42.4–66.5%). However, the results concerning the relative reliability showed higher ICC for absolute RMS values (ICC=0.82–0.92) compared with normalized values (ICC=0.57–0.72).The outcome measurements of this study with healthy subjects were found reliable and, therefore, have the potential to detect changes in muscle strength and muscle activity.