The aging population in Chile and worldwide is increasing, with older people expected to represent 32.1% of the population by 2050. This demographic shift brings age-related pathologies such as dementia, a leading cause of disability and dependence among older individuals globally. Mild cognitive impairment (MCI) precedes dementia and presents a critical therapeutic window for halting or slowing its progression. While resistance exercise training appears promising for this at-risk population, few studies have evaluated its effects on cognitive function and muscle strength in individuals with MCI.

Hypothesis: Twelve weeks of progressive resistance exercise training will significantly improve cognitive function, skeletal muscle mass, and strength in people over 60 years of age with MCI compared to the usual therapy in the control group.

Goal: The main objective of this study is to compare the effect of progressive resistance exercise training with usual therapy (control group) on cognitive function, skeletal muscle mass, and strength in individuals over 60 years of age with mild cognitive impairment.

Methodology: In this randomized controlled trial, 60 participants (both men and women) aged 60 years or older will be recruited. Participants will be identified with MCI using the Montreal Cognitive Assessment (MoCA) and the Pfeffer Functional Activities Questionnaire (PFAQ). They will be randomly assigned to two equal groups: a control group (receiving usual therapy) and an intervention group (receiving usual therapy plus resistance training). Participants in the control group will receive usual care for 12 weeks, including one medical review and one educational talk. Participants in the intervention group will maintain their usual therapy and will participate in supervised full-body resistance training with a kinesiologist, performing exercises three times per week for 12 weeks. All participants in both groups will be evaluated before (Pre-time 0) and after (Post-time 1) the intervention. During the evaluations, samples and measurements will be taken, including fasting blood samples for BDNF and CTSB measurement, whole-body dual-energy X-ray absorptiometry (DEXA) to assess global muscle mass, and magnetic resonance imaging of the quadriceps and brain. Global cognitive function will be evaluated using the ACEIII test, maximum strength with 1 repetition maximum (1RM), functional capacity with the Short Physical Performance Battery (SPPB), adapted Timed Up and Go (TUG) test, Activities of Daily Living Questionnaire (T-ADLQ). Finally, quality of life will be assessed using the WHOQOL-BREF scale. Expected Results: Few studies worldwide, and none in Chile, have evaluated the effects of resistance training on cognitive function, muscle mass, and strength gain in individuals with mild cognitive impairment, or the correlation between increased muscle strength and cognition. There are also no protocols or clinical guidelines for resistance training in this at-risk population. The impact of resistance exercise on cognitive function in individuals with MCI remains unclear. The proposed research will provide new insights into the effectiveness of resistance training on cognition in individuals with MCI over 60 years of age. We hope that our findings will be of significant value in the development of future interventions to prevent or postpone the progression of dementia.