INTRODUCTION: High-intensity interval training (HIIT) is a time-efficient strategy shown to induce various cardiovascular and metabolic adaptations. Little is known about the optimal tolerable combination of intensity and volume necessary for adaptations, especially in clinical populations. OBJECTIVES: In a randomized controlled pilot design, we evaluated the effects of two types of interval training protocols, varying in intensity and interval duration, on clinical outcomes in overweight/obese men. METHODS: Twenty-five men (body mass index (BMI) > 25 kg/m2) completed baseline body composition measures: fat mass (FM), lean mass (LM) and percent body fat (%BF) and fasting blood glucose, lipids and insulin (IN). A graded exercise cycling test was completed for peak oxygen consumption (VO2peak) and power output (PO). Participants were randomly assigned to high-intensity short interval (1MIN-HIIT), high-intensity interval (2MIN-HIIT) or control groups. 1MIN-HIIT and 2MIN-HIIT completed 3 weeks of cycling interval training, 3 days/week, consisting of either 10x1 min bouts at 90% PO with 1 min rests (1MIN-HIIT) or 5x2 min bouts with 1 min rests at undulating intensities (80% to 100%) (2MIN-HIIT). RESULTS: There were no significant training effects on FM (delta 1.06 +/- 1.25 kg) or %BF (delta 1.13% +/- 1.88%), compared to CON. Increases in LM were not significant but increased by 1.7 kg and 2.1 kg for 1MIN and 2MIN-HIIT groups, respectively. Increases in VO2peak were also not significant for 1MIN (3.4 ml/kg/min) or 2MIN groups (2.7 ml/kg/min). IN sensitivity (HOMA-IR) improved for both training groups (delta -2.78 +/- 3.48 units; p < 0.05) compared to CON. CONCLUSION: HIIT may be an effective short-term strategy to improve cardiorespiratory fitness and IN sensitivity in overweight males.
Abstract reprinted with permission from The McGraw-Hill Companies. All rights reserved.

Full text (sometimes free) may be available at these link(s):      help

• PubMed Central
• DOI
• PubMed
• PDF locator
• publisher