Angular position, range of motion and velocity of arm elevation: a study of consistency of performance.
BACKGROUND
To define the normal range, velocity and consistency of the movement of active arm elevation with humerus in neutral or in external rotation using a simplified kinematic model.


METHODS
Nine normal volunteers and the non-involved side of twenty five patients with unilateral shoulder lesion participated. A 3D optoelectronic tracking system was used to register the movement of raising the arm from the normal upright position to maximal elevation in a repetitive way. Peak humeral position, range of movement, velocity of motion and consistency of cycles were analyzed. Descriptive statistics, correlation between variables and with sex, age and side are presented, including differences between performances of movement done in neutral or external rotation.


RESULTS
Data of the six variables were: maximal abduction 142 degrees [137.4-147.0], range of motion 118.1 degrees [112-124], maximal velocity 238 degrees/s [209-265]; mean velocity 113 degrees/s [96-130]; coefficient of variation of maximal angular abduction was 2.2% [1.7-2.7]; coefficient of variation of maximal velocity 8.6% [7.3-9.9]. No significant differences were observed either on side, sex or between the shoulder of normal volunteers or that of the patients with opposite shoulder lesions. Participants older than 45 years old showed only a significant slightly lower average velocity. The study confirms the weak association between dependent (biomechanical) and independent variables.


CONCLUSIONS
As it is described here, analysis of arm elevation has not been previously studied and shows that has a good consistency in angular position, velocity and repeatability of motion in normal conditions which permits a picture of the overall performance of the shoulder.
García-Alsina
Joan
J
Instituto de Valoración Corporal, Roger de Llùria, 33, 08009 Barcelona, Spain. Garcia_alsina@invalcor.com
García Almazan
Concepción
C
Moranta Mesquida
José
J
Pleguezuelos Cobo
Eulogio
E
D000293:Adolescent; D000328:Adult; D001132:Arm / Q000502:physiology*; D001696:Biomechanical Phenomena; D016009:Chi-Square Distribution; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D016059:Range of Motion, Articular; D012399:Rotation; D012785:Shoulder Joint / Q000502:physiology*; D014741:Video Recording