Effects of Two Workload-Matched High-Intensity Interval Training Protocols on Regional Body Composition and Fat Oxidation in Obese Men

The effects of two high-intensity interval training (HIIT) protocols on regional body composition and fat oxidation in men with obesity were compared using a parallel randomized design. Sixteen inactive males (age, 38.9 +/- 7.3 years; body fat, 31.8 +/- 3.9%; peak oxygen uptake, VO2peak, 30.9 +/- 4.1 mL/kg/min; all mean +/- SD) were randomly assigned to either HIIT10 (48 x 10 s bouts at 100% of peak power [W-peak] with 15 s of recovery) or HIIT60 group (8 x 60 s bouts at 100% W-peak with 90 s of recovery), and subsequently completed eight weeks of training, while maintaining the same diet. Analyses of variance (ANOVA) showed only a main effect of time (p < 0.01) and no group or interaction effects (p > 0.05) in the examined parameters. Total and trunk fat mass decreased by 1.81 kg (90%CI: -2.63 to -0.99 kg; p = 0.002) and 1.45 kg (90%CI: -1.95 to -0.94 kg; p < 0.001), respectively, while leg lean mass increased by 0.86 kg (90%CI: 0.63 to 1.08 kg; p < 0.001), following both HIIT protocols. HIIT increased peak fat oxidation (PFO) (from 0.20 +/- 0.05 to 0.33 +/- 0.08 g/min, p = 0.001), as well as fat oxidation over a wide range of submaximal exercise intensities, and shifted PFO to higher intensity (from 33.6 +/- 4.6 to 37.6 +/- 6.7% VO2peak, p = 0.039). HIIT, irrespective of protocol, improved VO2peak by 20.0 +/- 7.2% (p < 0.001), while blood lactate at various submaximal intensities decreased by 20.6% (p = 0.001). In conclusion, both HIIT protocols were equally effective in improving regional body composition and fat oxidation during exercise in obese men.

Automated summary

A study comparing two high-intensity interval training protocols on obese men showed similar effects in improving regional body composition and fat oxidation. Both training programs effectively reduced trunk fat and increased leg lean mass, while enhancing fat oxidation during exercise. HIIT also resulted in improved peak fat oxidation, VO2peak, and decreased blood lactate levels at submaximal intensities.