Nonetheless, the findings have garnered significant interest from a public health perspective, given one of the most commonly cited barriers to regular exercise participation is “lack of time”. The potential for very low-volume interval training protocols to improve VO2 peak has also been described by Ma et al. and Hazell et al. Metcalfe et al. also reported that insulin sensitivity based on oral glucose tolerance tests was improved after training in men but not women, highlighting the potential for sex-based differences in the adaptive response. Only one study has examined muscle adaptations to this type of training, with Ma et al. reporting increased protein content of some mitochondrial enzymes after training, although the maximal activity of citrate synthase was unchanged. The purpose of the present study was to clarify and advance our understanding of the impact of very low-volume interval training on physiological and health related adaptations to very lowvolume SIT. Specifically, we examined the impact of a training protocol that involved only 1 minute of intense intermittent exercise within a 10 min time commitment, including warm-up and cool-down. Sedentary but otherwise healthy subjects trained 3x/wk for 6 wk, and needle biopsies were obtained before and after training to examine skeletal muscle remodeling. We also assessed changes in several markers reflective of cardiometabolic health. In light of the findings by Metcalfe et al., a secondary aim was to explore potential sex-based differences in the adaptive response to this type of training. We hypothesized that the training intervention would increase skeletal muscle oxidative capacity, as reflected by the maximal activity and protein content of mitochondrial enzymes, increase VO2 peak, and GDC-0449 reduce resting blood pressure and 24 h mean blood glucose concentration measured using continuous glucose monitoring under conditions of controlled activity and feeding. We further hypothesized that reductions in 24 h glucose would be superior in men. The main finding from the present study was that short-term interval training, using a protocol that involved only 1 min of very intense exercise within a total time commitment of 10 min, was a potent stimulus to induce physiological adaptations that are linked to improved health in overweight and obese adults. Our general design, which involved 3 sessions per week for 6 wk, was similar to recent studies by Metcalfe and Ma, but clarified outstanding questions regarding the potential for very low-volume interval training to increase muscle oxidative capacity, resting blood pressure and aspects of glycemic control. Despite the small sample size, we also found evidence of potential sex-specific adaptations to this type of training that warrant further investigation. Clearly, there is some minimal total volume of SIT necessary to acutely stimulate mitochondrial biogenesis, which when performed repeatedly leads to measureable increases in enzyme protein content or maximal activity. The various shortterm, very low-volume SIT protocols that have been employed to date are likely on the lower end of this threshold, which may in part explain the equivocal results to date. Additional studies, like the elegant work by Perry et al., which characterized the early time course of adaptation to HIIT, will help to resolve this matter. Similar to the pre-training CGM data, it is possible that the higher baseline value for b-HAD in women in the present study reduced their potential to increase the capacity for lipid oxidation compared to men.