Testing the Effect of Exercise Intervention Using a SMART Design.

Exercise is the most effective way on reducing visceral adipose tissue (VAT), which is strongly linked with obesity to hypertension, cardiovascular disease, and insulin resistance. However, the current exercise dosage for reducing VAT cannot be accurately quantified. The aims of this study are to develop and test the optimal exercise dosage and sequence for reducing VAT in overweight and obese community residents. Purposive sampling will be used to enroll at least 206 participants aged 40-65 years and body fat more than 30% without diet control from 2 community centers in southern Taiwan. The project will use the sequential multiple assignment randomized trial (SMART) design to conduct a 16-week 2-stage (each for 8-weeks) adaptive exercise intervention for community residents. In the first stage, participants will be randomized into groups performing 8 weeks either moderate intensity of aerobic exercise or interval training 3 times per week. Participants whose VAT does not decrease by over 3%, measured using a body composition analyzer, compared with the baseline will be 1:1 rerandomized into groups with aerobic exercise combined with resistance exercise or received the exchange of first stage treatment (interval training or aerobic exercise) in the second stage. Those with substantial response to the first-stage intervention (VAT reduction of more than 3%) will continue to receive the same exercise treatment until 16 weeks. Linear mixed model, weighted and replicated regression will be used to identify the optimal sequence of exercises for the greatest reduction in VAT. The findings can assist clinical health workers to develop exercise prescriptions for effectively reducing VAT, and help community residents reduce VAT through exercise to achieve the health promotion.