High-intensity interval training for health and fitness in males with overweight or obesity.

High-intensity interval training (HIIT) - randomized trial with moderate-intensity continuous training (MICT) acting as the comparator group to HIIT. Participants were randomly assigned (1:1) to a HIIT or MICT training group. - Exercise training sessions conducted over 6 weeks x 3 sessions per week. - all training conducted at a single site (university exercise research lab) where both groups trained in parallel. HIIT protocol details: Participants trained 3 times per week for 6 weeks. A minimum of 24 hours between training sessions was required and no more than two consecutive days of training. All training was conducted on manual-resistance cycle ergometers (Monark 828E Sweden) or electronically-braked cycle ergometers (Monark 928E; for HIIT participants only due to its ability to pre-programme interval training sessions). All sessions were supervised by trained research assistants (undergraduate Exercise Physiology students). Heart rate (HR) and rating of perceived exertion (RPE) were monitored throughout every training session using a Polar T34 heart rate monitor and unmodified (6-20) Borg scale 20 respectively. For HIIT participants, HR and RPE were recorded at the end of every 2nd interval and recovery period. HIIT sessions consisted of 10 × 1-minute intervals at 90-100% Wmax (approximating ~90% HRmax; RPE ~15), interspersed with 1 minute of active recovery at 15% Wmax. The intensity of training was progressively increased over the 6-week intervention (weeks 1 and 2: 90% Wmax; weeks 3 and 4: 95% Wmax; weeks 5 and 6: 100% Wmax). Each session began with a 3-minute warm-up at 35% Wmax (approximating 65% HRmax) and ended with a 2-minute cool down at 15% Wmax. Total exercising time for each session was 24 minutes for the HIIT group. Adherence was assessed by number of sessions attended. Compliance was assessed by monitoring HR in relation to desired HR target range for each session. Safety was assessed by reports of adverse events during or within 4 hours following each session.