Figure 1.

Typical subject performing a 20-s work 40-s rest self-paced intermittent cycling time trial lasting 30 min (i.e., 30 repetitions). Data are from Nicolò et al. (2014a). The time course of power output is depicted in (A). Of note, f_R responds very fast to the alternation of the work and recovery phases, and increases progressively over time (B). The rapid change in f_R according to variations in workload can be better observed by showing the time course of f_R within the 60-s work-recovery cycle (C). The solid thick line represents the average of the entire trial, the dashed lines represent each repetition and the solid vertical line separates the 20-s work from the 40-s recovery. For details on this analysis see Nicolò et al. (2014b). This is also a convenient representation to show f_R data real time during HIIT. In order to synthesize the effort of the training session, the f_R distribution (D) and concentration (E) profiles have also been constructed. The distribution profile describes the time spent above each f_R-value, while the concentration profile describes the time spent at each f_R-value. Both analyses can also be used to describe several training sessions. See Kosmidis and Passfield (2015) for more details on the two analyses.