The purpose of this study was to quantify the time-magnitude changes in cardiometabolic health outcomes that occur with cessation of regular exercise training. All participants (n = 22) performed baseline testing, completed a 13-week exercise program, and completed post-program testing. Upon completion of the 13-week exercise program, participants were randomized to one of the following two treatment groups: (1) the treatment group that continued their exercise for 4 weeks (TRAIN); or (2) the treatment group that discontinued exercise (DETRAIN). Changes from baseline to 13 weeks in both the TRAIN and DETRAIN treatment groups for maximal oxygen consumption (VO₂max), body fat percentage, mean arterial pressure, high-density lipoprotein (HDL) cholesterol, and triglycerides were significantly favourable (p < 0.05). VO₂max, body fat percentage, and favourable cardiometabolic health adaptations continued to improve (p < 0.05) with an additional one month of exercise training. Upon cessation of exercise, all measures of VO₂max and body fat percentage, along with mean arterial pressure, HDL cholesterol, and triglycerides significantly worsened (p < 0.05) in the DETRAIN treatment group. Favourable training adaptations were further enhanced with an additional month of continued exercise training, and cessation of regular exercise rapidly abolished all training adaptations within one month. These novel findings underscore the importance of sustained and uninterrupted exercise training.
Keywords: aerobic training; cardiorespiratory fitness; metabolic syndrome; physical inactivity; resistance training.