The strengths of this study include 1) the inclusion of a lean, healthy group to rule out attenuated responses due to obesity or type 2 diabetes, 2) the application of a HIIT-protocol recruiting several lower and upper body muscle groups to maximize the insulin-sensitizing effect, 3) the supervised, group-based training sessions and the non-weight-bearing approach to ensure adherence and lack of injuries, and 4) conduction of the majority of the training sessions in the afternoon, which may enhance the metabolic benefits (32, 41). The gene discussed is INS; the disease is obesity due to melanocortin 4 receptor deficiency.