Reproducibility of trunk isoinertial performances in the sagittal, coronal, and transverse planes.

A new triaxial dynamometer to quantify the performance of trunk muscles has been developed, and a study was conducted to determine the best control parameters to use with this triaxial isodynamic mode of testing. Nine male subjects were tested at three resistance levels in the sagittal, coronal, and transverse planes. The purpose was to establish the reproducibility of the performance parameters in each plane at all resistance levels, and to identify those parameters which gave the most reliable information for objective assessment of the low back functional state. Measured torque had the highest reproducibility rate, and the most reliable assessments were obtained at the highest resistance level.