Reliability and validity of eccentric strength measurement of the shoulder abductor muscles using a hand-held dynamometer.

OBJECTIVES

To investigate the validity and intrarater and interrater reliability of eccentric strength testing of the shoulder abductors using a hand-held dynamometer (HHD) versus an isokinetic dynamometer.

DESIGN

Methodological.

SETTING

Research laboratory and athletic training room.

PARTICIPANTS

Forty-seven asymptomatic shoulders of 25 participants were tested in 2 sessions by 2 physiotherapists.

MAIN OUTCOME MEASURES

Eccentric strength of the shoulder abductors was measured from 120° to 30° scapular plane abduction using the HHD and isokinetic dynamometer. A gyroscope was used to validate the velocity. Spearman's rank correlation coefficients, intraclass correlation coefficient (ICC), standard error of measurement (SEM), and minimal detectable change (MDC) were calculated.

RESULTS

The measurement protocol showed excellent intrarater (ICC[3,3] = 0.987, SEM = 2.59 Nm and MDC = 7.18 Nm) and interrater (ICC[3,3] = 0.990, SEM = 2.28 Nm and MDC = 6.32 Nm) reliability. HHD and isokinetic dynamometer measurements were strongly correlated (rho = 0.760, p < .001). Velocities during HDD testing were similar to those of the isokinetic dynamometer (30°/s) (p > .050).

CONCLUSIONS

Eccentric strength testing of the shoulder abductors using an HHD is a valid and reliable method that can be used for research and clinical purposes when an isokinetic dynamometer cannot be used.