This study examined the reliability/validity of power output measured using the Fortius Virtual Reality cycle trainer. 10 cyclists (age: 28±6 years; V?O2max: 60.9±7.2 ml · kg-1 · min-1; peak power: 393±82 W) completed three 20 km time trials on a Fortius cycle trainer. During each time trial, power output was measured at 1 Hz using the Fortius internal software and a PowerTap power monitor. Validity calculated for the Fortius trainer; Pearson correlation coefficient (r=0.99; 95% CI: 0.98-0.99; p<0.01) and typical error of estimate (3.5%; 95% CI: 3.2-3.9%), was similar to other established laboratory ergometers. No differences (F2,16=0.32; p=0.73) in mean 20 km power were observed between trial 1 (253±46 W), 2 (258±49 W), or 3 (255±50 W). Test-retest reliability (intraclass correlation coefficient (ICC) and coefficient of variation (CV)) was better between trial 2 and 3 (ICC=1.00 (CI: 0.98-1.00); CV: 1.6% (CI: 1.1-3.3%)) compared with trial 1 and 2 (ICC=0.98 (CI: 0.91-1.00); CV: 3.3% (CI: 2.2-6.4%)). The Fortius cycle trainer is a valid and reliable device for the measurement of power output in cyclists, thus providing an alternative to larger more expensive laboratory ergometers.
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