Effects of various interval training regimes on changes in maximal oxygen uptake, body composition, and muscular strength in sedentary women with obesity

Purpose We determined the effects of two high-intensity interval training (HIIT) regimens [the traditional (TRAD) and periodized (PER)] on changes in maximal oxygen uptake (VO 2 max), body composition, and muscular strength in sedentary, obese women. Methods Seventeen women (age and BMI = 37.5 ± 10.5 year and 39.1 ± 4.3 kg/m 2 ) were randomized into a 6 week regime of TRAD or PER which consisted of three sessions per week, two in the laboratory, and one on their own. Pre- and post-training, VO 2 max, body composition, and muscular strength of the knee extensors (KE) and flexors (KF) were assessed via ramp cycling to exhaustion, air displacement plethysmography, and isokinetic dynamometry, respectively. Results VO 2 max was increased by 4–5% in response to training ( p = 0.045) with no group-by-time interaction ( p = 0.79). Body mass, fat mass, and waist-to-hip ratio were unaltered ( p > 0.05) in response to training, yet there was a significant change in percent body fat ( p = 0.03), percent fat-free mass ( p = 0.03), and absolute fat-free mass ( p = 0.03) in TRAD but not PER. No change occurred in KE ( p = 0.36) or KF torque ( p = 0.75) in response to training and there was no group-by-time interaction ( p > 0.05). Conclusions Low-volume HIIT improved VO 2 max and body composition but did not modify muscular strength, which suggests that obese women desiring to increase strength should initiate more intense HIIT or partake in formal resistance training.