This study investigated body composition, cardiorespiratory, and neuromuscular adaptations induced by three high intensity trainings easy to fit into daily routine. Thirty-seven adults participated in one of the following 8-week interventions: vigorous intensity continuous training (VICT; 28 min at 70% of peak oxygen uptake [VO2peak]), long interval high intensity interval training (LI-HIIT;6 × 2 min at 85% VO2peak), or short interval HIIT (SI-HIIT; 12 × 30 s at 125% maximal power output). Heart rate (HR) and rating of perceived exertion (RPE) were measuredduring sessions. Pre-and post-intervention assessments included fat and lean mass, cardiopulmonary exercise testing, knee extensors maximal isometric torque, voluntary activation, and endurance during a submaximal contraction.
Compared to SI-HIIT and VICT, LI-HIIT sessions were characterized by a shorter duration, a similar time spent above 90% HRmax, but a higher RPE (p < 0.05). VO2peak and muscle endurance increased respectively by 14% and 12%, while knee extensors torque, voluntary activation, and lean mass increased to a lesser extent (1%–3%) after the interventions (ANOVA time-effect, all p < 0.05). There was no significant difference between the modalities (intervention × time interaction, all p > 0.05). In conclusion, comparable body composition, cardiorespiratory, and neuromuscular adaptations were induced by the three high intensity training protocols, while RPE was higher during LI-HIIT sessions.