The Effects of Low Volume High Intensity Interval Training vs. Periodized High Intensity Interval Training on Cardiorespiratory Fitness in Sedentary Women with Obesity

Objective: To investigate effects of two high intensity interval training (HIIT) regimes on changes in maximal oxygen uptake (VO2max), O2 pulse and ventilatory threshold (VT) in obese, sedentary women. Methods: 17 obese sedentary women (age and BMI=37.5±10.5 years and 39.0±4.7 kg/m2) participated in a six-week exercise intervention with three training sessions per week. Participants were randomized to low volume HIIT (LOW) (n=9, VO2max=21.5±3.2 mL/kg/min) or periodized HIIT (PER) (n=8, VO2max=17.3±2.4mL/kg/min). VO2max and peak power output (PPO) were measured on a cycle ergometer at baseline and at 3 and at 6 weeks using a ramp exercise test. Women in LOW completed repeated 60 second bouts of HIIT at 70-85% PPO; whereas, women in PER performed a different number of bouts and intensities each week. Results: There was a significant difference in relative (p=0.002; LOW: 21.5±3.2 vs. 22.5±3.2 mL/kg/min; PER: 17.3±2.41 vs. 18.0±2.2 mL/kg/min) and absolute (p=0.001; LOW: 2.1±0.3 vs. 2.2±0.3 L/min; PER: 1.9±0.4 vs. 2.0±0.3 L/min) VO2max across time, but no interaction (p=0.79 and p=0.53). There was no change in VT expressed as VT % VO2max (p=0.24) yet there was a group X time interaction (p=0.043). VT expressed in Watts was significantly different over time (p=0.001) but there was no group X time interaction (p=0.09). O2 pulse significantly increased from pre- to post-training (p=.003) but there was no time X group interaction (p=0.95). Conclusion: Although there were no significant differences between regimes, HIIT elicits significant changes in VO2max, O2 pulse and VT in sedentary women with obesity, which are improve health status.