2.4. Outcome

The VPT was the main study measure. It was evaluated before starting the vibration and immediately after each training session. VPT was assessed using the Vibratron II (Physitemp Instruments, Clifton, NJ, USA). The device produces vibration amplitudes from 0.005–200 microns, expressed as vibration units (0.005 microns = 0.1 vibration unit; 200 microns = 20.0 vibration units), with a higher vibration unit value indicating worse performance or greater sensory dysfunction.

The vibration units are the Vibraton II measure units. These vibration units are related to the movement amplitude measured in microns, and they follow the following formula:

A = x²/2 (where x is the vibration units [vu] and A is the amplitude in microns [μ]).

The “two-alternative forced-choice procedure” was the measure protocol, and the final VPT calculation used in this study. This protocol is recommended by the manufacturer, and it has been previously used in several studies [23,24].