Applicability of a supramaximal high-intensity interval training program for older adults previously not engaged in regular exercise; analyses of secondary outcomes from the Umeå HIT Study

This analysis of secondary outcomes investigated the applicability of supramaximal High-intensity interval training (HIT) with individually prescribed external intensity performed on stationary bicycles. Sixty-eight participants with a median (min;max) age of 69 (66;79), at the time not engaged in regular exercise were randomized to 25 twice-weekly sessions of supramaximal HIT (20-minute session with 10 × 6-second intervals) or moderate intensity training (MIT, 40-minute session with 3 × 8-minute intervals). The primary aim was outcomes on applicability regarding; adherence to prescribed external interval intensity, participant reported positive and negative events, ratings of perceived exertion (RPE 6–20), and affective state (Feeling Scale, FS -5–5). A secondary aim was to investigate change in exercise-related self-efficacy (Exercise Self-Efficacy Scale) and motivation (Behavioural Regulations in Exercise Questionnaire). Total adherence to the prescribed external interval intensity was [median (min;max)] 89% (55;100%) in supramaximal HIT, and 100% (95;100%) in MIT. The supramaximal HIT group reported 60% of the positive (112 of 186) and 36% of the negative (52 of 146) events. At the end of the training period, the median (min;max) session RPE was 15 (12;17) for supramaximal HIT and 14(9;15) for MIT. As for FS, the median last within-session rating was 3 (-1;5) for supramaximal HIT and 3 (1;5) for MIT. Exercise-related motivation increased (mean difference in Relative Autonomy Index score= 1.54, 95% CI [0.69;2.40]), while self-efficacy did not change (mean difference = 0.55, 95% CI [-0.75;1.82]), regardless of group. This study provide support for supramaximal HIT in supervised group settings for older adults.