Reduction in Resistance Training Volume and Neuromuscular Adaptations in Older Adults

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.