Validity of the 8-minute time trial in determining variables for mountain bike cycling training

Abstract

The 8-minute time trial (TT) is a methodological alternative to the 60-minute TT for evaluating the Functional Threshold Power (FTP) of cyclists, however, studies that tested its validity were not found in the researched literature. Therefore, research aims to assess the validity of the 8-minute TT. The study included 9 trained male cyclists, aged between 25.46 ± 7.49 years, who were assessed on three different days. On the first day, we measured personal data, anthropometrics, ventilatory thresholds and peak oxygen consumption. On the other days, we submitted the volunteers to the 8- and 60-minute TT. We analyzed the agreement between the procedures using the intraclass correlation coefficient (ICC) and its validity by Bland-Altman. We adopted a significance level of 5%, and we performed all analyses using the SPSS. The results suggest great agreement, especially between the second 8-minute stimulus and the reference test, for FTP (ICC: 0.792, p= 0.016), Wats per kilogram (ICC: 0.952, p< 0.001), Wats per kilogram of lean mass (ICC: 0.912, p= 0.001) and peak oxygen consumption (ICC: 0.882, p= 0.001). In addition, in all these variables, the volunteers were within the mean ± two standard deviations, as verified by the Bland-Altman plots. These results demonstrate the validity of the 8-minute TT, with more robust data being observed by the second stimulus of this protocol.