Affiliations: [a] Musculoskeletal Surgery, Department of Surgery,
Anaesthesia & Intensive Care, Faculty of Medicine, Imperial College London
Charing Cross Hospital, London W6 8RF, UK
Abstract: Background: Measuring isokinetic strength of the shoulder complex is
potentially an important clinical tool in both diagnosis and management of
injury and pathology. However, a clinically relevant position is yet to be
established. Objectives: To establish an appropriate and repeatable protocol to
evaluate the functional strength of both internal and external rotators of the
glenohumeral joint to enable assessment of clinical injury management and
training related developments in upper limb strength. Methods: A population cross-sectional study of shoulder internal and
external rotational strengths of 17 normal, healthy volunteers (11 males, 6
females) aged 21 to 45 years were measured both isokinetically and
isometrically. Two test positions: seated and supine, were compared by way of
reliability and repeatability analyses. Humeral rotation was performed at
45° of abduction in the scapular plane seated, and at 90° of abduction
in the supine position. Results: Throughout concentric testing, when the population was
considered as a whole the left shoulder data appeared more repeatable than the
right shoulder. This however, was not evident when the study population was
divided into single sex groupings. Equally, whilst the repeatability trend of
sitting vs. supine position was skewed towards the former, more evident in the
left shoulder, this was less apparent when sexes were analysed separately. All
comparative measures were statistically insignificant. Conclusion: The findings of this study suggest that measurements of
isokinetic shoulder rotation strength are highly prone to both joint specific
and non-specific errors.
