The SmartRX trial: Acute effectS of manipulating stRength eXercise volume on insulin sensitivity in overweight/obese adults: a protocol for a randomized controlled, crossover, clinical trial

Abstract Background: Type 2 diabetes mellitus is a disease in which insulin action on sensitive tissues is impaired, and even an acute bout of strength exercise can cause positive changes on insulin sensitivity. Current guidelines for strength exercise prescription suggest that 8 to 30 sets should be performed, although it is not known how such variations in volume impact insulin action. Additionally, this means an almost 4-fold difference in time commitment, which might directly impact an individual’s motivation and perceived capacity to exercise. This study will assess the effects of different strength exercise volumes on insulin sensitivity. Methods: Fourteen overweight/obese individuals of both sexes who are over 35 years old will undergo 3 experimental sessions in a random order, with a minimum washout period of 4 days between them, after being thoroughly familiarized with the procedures: Session 1: high-volume (7 exercises, 3 sets per exercise, 21 total sets)]; Session 2: low-volume (7 exercises, 1 set per exercise, 7 total sets); Session 3: control session, where no exercise will be performed. Psychological assessment (affect, enjoyment, and self-efficacy) will be performed after the sessions. All sessions will be held at night, and the next morning, an oral glucose tolerance test will be performed in a local laboratory, from which indexes of insulin sensitivity will be derived. Discussion: We believe this study will aid in strength exercise prescription for those individuals who claim not to have time to exercise and to those who perceive high-volume strength exercise intimidating to adhere to. Trial registration: Clinical trial registry number: ReBEC #RBR-3vj5dc5 (https://ensaiosclinicos.gov.br/rg/RBR-3vj5dc5) World Health Organization Universal Trial Number (UTN): U1111-1287-9212 Open Science Framework (OSF): https://osf.io/4gu87/