Load and psychophysiological responses in high-intensity interval training with fixed and self-selected recovery

Introduction and Objective. The study analyzed the training load in high-intensity interval training sessions with different conditions of recovery time between stimuli: fixed (1min.) and self-selected. Methods. Nineteen individuals participated in the study: 13 men and 6 women (19±1.0 years; 64.0±9.2 kg; 169±8.5 cm; 22.0±2 BMI). For the training load analysis, heart rate variability (LnRMSSD), perceived effort (PE), and mood scale BRUMS (MS) were used. LnRMSSD and MS were evaluated before and after the sessions. The PE was evaluated during each session immediately after each stimulus. The protocol was 10 x 30s (95% Vpeak) with active recovery (40% Vpeak) in fixed or self-selected time. ANOVA-RM (2 [interventions] x 2 [time points]) for LnRMSSD and MS and (2 [interventions] x 10 [time points]) for PE was used. Results. Between condition and time*condition, no differences were observed for LnRMSSD (p=.626; p=.879, respectively), PE (p=.191; p=.792, respectively), and MS (tension: p=.673; p=.463; depression: p=.867; p=.359; anger: p=.867; p=.359; vigor: p=.811; p=.778; fatigue: p=.144; p=.998; mental confusion: p=.828; p=.752, respectively). In terms of time, significant differences were observed in LnRMSSD (p