Reduction in Resistance Training Volume and Neuromuscular Adaptations in Older Adults

The goal of this clinical trial is to evaluate how reducing resistance training volume affects neuromuscular adaptations in older adults aged 60 to 70 years. The main questions it aims to answer are: Can strength and muscle adaptations be maintained with lower training volume? Does reducing training volume influence muscle power and hypertrophy in older adults? Researchers will compare two groups: A group that reduces training volume in one or both legs A group that maintains the same training volume in both legs to see if reducing volume leads to different neuromuscular outcomes. Participants will: Complete an initial 10-week strength training program (2x/week) using unilateral leg press and knee extension machines, performing 3 sets per exercise Undergo tests for muscle strength (1-RM), muscle thickness (ultrasound), and power (isokinetic dynamometry) at weeks 0, 5, and 10 After 10 weeks, be randomly assigned to: A reduced-volume group: one leg does 2 sets and the other 1 set per exercise Or a control group: both legs continue doing 3 sets Continue training for another 10 weeks under the assigned protocol Repeat strength, muscle thickness, and power assessments at weeks 5 and 10 of phase 2 Attend a dietary intake interview with a registered dietitian This study will help determine the minimum effective training volume needed to maintain strength and muscle health in older adults, potentially improving long-term adherence to exercise programs.

Aging is associated with a progressive decline in muscle strength, muscle mass, and power, which can negatively affect functional capacity and quality of life in older adults. Resistance training (RT) is widely recognized as an effective intervention to mitigate these neuromuscular declines; however, adherence and long-term sustainability of high-volume RT programs can be challenging in this population due to reduced recovery capacity and potential lifestyle constraints. In this context, identifying the minimum effective training volume necessary to maintain neuromuscular adaptations is essential, as lower volumes may increase adherence among older adults. Therefore, this randomized, controlled clinical trial aims to investigate the effect of reducing RT volume on neuromuscular outcomes in older adults aged 60 to 70 years. The study will be conducted in two phases. In Phase 1, all participants will complete a 10-week RT program (2 sessions/week), performing three sets of unilateral leg press and knee extension exercises, with assessments of strength (1RM), muscle thickness (via ultrasound), power (via isokinetic dynamometry), body composition (via DXA), and dietary intake (via 24-hour recall) conducted at baseline, week 5, and week 10. Participants will be familiarized with the training procedures, and reliability in strength testing will be confirmed prior to the intervention. In Phase 2, participants will be randomized according to the delta (%) change in knee extension 1RM and assigned to one of two groups: a reduced-volume group, in which one leg performs two sets and the other one set (intra-subject design), or a control group maintaining three sets per leg. This second phase will also last 10 weeks, with follow-up assessments at weeks 5 and 10. The unilateral training design allows for within-subject comparisons to assess the impact of reduced volume, and the control group allows for between-group analysis, facilitating the identification of individual responses and determining whether neuromuscular adaptations can be maintained with lower training volumes after a standard RT protocol.