CONTEXT: Shoulder external rotators are challenged eccentrically throughout the deceleration phase of throwing which is thought to contribute to overuse injuries. In order to evaluate the effectiveness of intervention programs as well as identify deficits, reliable and responsive measures of isometric and eccentric shoulder external rotation are necessary. Previously, isometric measures have primarily tested a single position and eccentric measures have not been found to have high reliability.
OBJECTIVE: To examine the between day reliability of multiple angle isometric and dynamic eccentric isokinetic testing of shoulder external rotation.
DESIGN: Repeated measures Participants: 10 healthy subjects (age: 30 ± 12 years, height: 166 ± 13 cm, mass: 72 ± 10 kg) Main Outcome Measures: Average isometric peak torque of shoulder external rotation at 7 angles was measured. From these values, the angle of isometric peak torque was calculated. Dynamic eccentric average peak torque, average total work and average angle of peak torque were measured.
RESULTS: Between day reliability was high for average peak torque during isometric contractions at all angles (ICC ≥ 0.85) as well as dynamic eccentric average peak torque (ICC ≥ 0.97) between days. The estimated angle of isometric peak torque (ICC ≤ 0.65) was not highly reliable between days. The average angle of peak torque from the eccentric testing produced inconsistent results. Average total work of dynamic eccentric shoulder external rotation was found to be highly reliable between days (ICC ≥ 0.97).
CONCLUSION: Measures of force such as peak torque and total work, in isometric and eccentric testing of the shoulder external rotator muscles can be measured reliably between days and used to objectively evaluate shoulder strength and identify changes when they occur. Angle measurements of peak torque could provide insight into the mechanical properties of the posterior shoulder muscles but were found to be inconsistent between days.
The project described was supported by the National Center for Advancing Translational Sciences, National Institutes of Health, through grant number UL1TR000117. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.
Papotto, Brianna M.; Rice, Thomas; Malone, Terry; Butterfield, Timothy; and Uhl, Tim L., "Reliability of Isometric and Eccentric Isokinetic Shoulder External Rotation" (2015). Rehabilitation Sciences Faculty Publications. 58.