Table 1. UEF parameter definitions.

See (15) for more details.

Parameter	Definition
Speed	Mean value (within 20-second elbow flexion/extension) of elbow angular velocity range (maximum minus minimum speed)
Range of motion	Mean value of elbow flexion range
Power	Mean value of product of the angular acceleration range and the range of angular velocity
Rise time	Mean value of time required to reach the maximum angular velocity
Moment	Mean value of maximum moments on elbow within each flexion/extension estimated from moment of inertia of forearm and hand, and elbow motion
Speed variability	Coefficient of variation (standard deviation divided by the mean value) of angular velocity range
Speed reduction	Difference in angular velocity range between the last and the first five seconds of elbow flexion as a percentage of initial angular velocity range
Flexion number	Number of flexion/extensions during 20 seconds

Normal-paced 6MWD test was performed following the standard guidelines of the European Respiratory Society and the American Thoracic Society [11]; the total distance covered was recorded to the nearest meter.