Dose-Response to Resistance Exercise on Cardiovascular Health

Participants will be randomly assigned to 1 of four research conditions at varying dosage of resistance exercise (RE) for the duration of 1 year, either 0 min, 30 min, 60 min or 120 min of weekly RE in addition to 60 min of weekly aerobic exercise (AE). Total exercise duration will be split between 2 weekly sessions. Participants in all four groups will receive healthy lifestyle education sessions, and will track daily steps, food intake and activity levels throughout the 1-year intervention. Participants will also complete baseline, 6-month, and 12-month physical examinations, which will include assessments of blood pressure, blood lipids, body composition, and aerobic and muscular fitness. During the first 6 months of intervention will occur in a supervised lab-based setting. Changes in Cardiovascular disease (CVD) risk factors, as well as potential mechanisms (arterial stiffness and inflammatory markers) that might explain a J-shaped dose-response, from baseline to 6 months will be assessed in each of the 4 groups. The second 6 months will follow the same exercise intervention as the first 6 months. However, all participants will be provided with a free health club membership. The second 6 months will be used to investigate the RE dose associated with best adherence in a free-living environment during the second 6 months. In addition, all measures taken at 6 months will also be assessed again at 12 months to examine the long-term effects of different doses of RE as secondary outcomes, given that compliance will not be tightly "enforced" by staff in this unsupervised free-living condition. In this case, the investigators will further carefully consider exercise adherence in data analysis.