Interindividual variation in cardiometabolic health outcomes following 6 months of endurance training in youth at risk of type 2 diabetes mellitus

Abstract

This study determined the interindividual variation in the cardiometabolic response to 6 months of moderate or vigorous intensity exercise training (ET) among youth at risk for type 2 diabetes mellitus. Youth were randomized to moderate intensity ET (45–55% heart rate reserve; n = 31), vigorous intensity ET (70–85% heart rate reserve; n = 37), or control (n = 36). Only those attending ≥70% of ET sessions were included. Cardiometabolic measures included insulin sensitivity, hepatic triglyceride content, visceral adipose area, and cardiorespiratory fitness. The contribution of ET to interindividual variation was determined using the standard deviation of individual responses (SDIR) and considered meaningful if the SDIR surpassed the smallest worthwhile difference (SWD), calculated as 0.2 × the standard deviation of the control group baseline values. ET meaningfully contributed to the interindividual variation among changes in peak oxygen uptake following moderate (SDIR: 2.04) and vigorous (SDIR: 3.43) ET (SWD: 1.17 mL·kg fat free mass−1·min−1), body fat percentage and hepatic triglyceride content following moderate-intensity ET (SDIR: 1.64, SWD: 1.05%; SDIR: 10.08, SWD: 1.06%, respectively), and visceral fat mass following vigorous ET (SDIR: 11.06, SWD: 7.13 cm2). Variation in the changes in insulin sensitivity were not influenced by ET. The contribution of ET to interindividual variation appears to be influenced by the desired outcome and prescribed intensity. Trial registration at ClinicalTrials.gov (identifier no.: NCT00755547). Novelty: The contribution of exercise to interindividual variation following training depends on the outcome and exercise intensity. Increasing exercise intensity does not systematically reduce non-response among youth at risk for type 2 diabetes.