Effects of Resistance Exercise with Instability on Neurocognitive Functions (REI STUDY): Study Protocol for a Proof-of-Concept Clinical Trial in Older Adults with Subjective Cognitive Complaints

Abstract Aim: Resistance exercise (RE) is a widely accepted strategy to counteract the effects of aging and chronic diseases on health-related outcomes. Studies have been suggested that RE improves brain and cognitive health. RE with unstable devices (REI) is a neuromotor complexity strategy with the potential to improve strength, power, and balance in onder adults, however, their effects on neurocognitive function in individuals at risk of cognitive decline are poorly understood. Thus, we describe the REI study protocol, a randomized clinical trial design to assess the effects of 12-weeks of REI and RE on neurocognitive functions in older adults with subjective cognitive complaints. Methods: The sample will consist of individuals (aged 65 or older) with subjective cognitive complaints, who will be randomized in one of three experimental groups: control, RE or REI. Participants of the RE group will receive 12-weeks of progressive resistance training (seven exercises structured into 3 sets of 10-15 repetitions maximum, three times per week). Participants of the REI group will receive the same RE protocol performed on unstable devices that promote progressive instability. The control group received a health education program. The primary outcome is a composite score of neurocognitive functions. Secondary outcomes include each separately neurocognitive domain, functional performance, balance, falls-related parameters, cardiovascular and mood variables. The study results will provide information to design a future and larger preventive trial on populations at risk of cognitive decline and dementia, which is imperative in public health terms. Trial registration: Brazilian registry of clinical trials number RBR-4kqs22.