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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
SINGLE
Enrollment
45
The mininum resistance training volume (12 sets/week) will be applied.
School of Physical Education and Sports of Ribeirão Preto
Ribeirão Preto, São Paulo, Brazil
Maximum Dynamic Strength (1-RM) in Knee Extension and Leg Press (kg)
This measurement will be assessed in both stages of the study. In Phase 1 (initial training), 1-RM testing will be performed for unilateral knee extension and unilateral leg press exercises. After a familiarization session, participants will complete up to three testing sessions, 72 hours apart, until consistent values (≤5% variation) are reached. Assessments will be conducted at baseline (week 0), mid-intervention (week 5), and post-intervention (week 10). In Phase 2 (volume manipulation), 1-RM measurements will be repeated at weeks 5 and 10, following the same standardized testing procedures. All evaluations will be performed at least 72 hours after the last training session to minimize the influence of acute fatigue on strength performance.
Time frame: Up to end of study data collection (both stages), i.e., assessed up to 1 year
Muscle Thickness (cm) - Quadriceps Muscle Group (Ultrasound)
This measurement will be assessed in both stages of the study. In Phase 1, muscle thickness of the quadriceps will be measured by B-mode ultrasound imaging at baseline (week 0), mid-intervention (week 5), and post-intervention (week 10). Measurements will be performed on both legs following a standardized protocol, with the participant in a rested state. In Phase 2, the same procedure will be followed to reassess muscle thickness at weeks 5 and 10, with all evaluations occurring at least 72 hours after the last training session to reduce the influence of acute changes in muscle size.
Time frame: Up to end of study data collection (both stages), i.e., assessed up to 1 year
Thigh Fat-Free Mass (kg) - Dual-Energy X-ray Absorptiometry (DXA)
This measurement will be assessed in both stages of the study. Thigh fat-free mass will be evaluated by DXA scan at five time points: baseline (week 0), mid-intervention (week 5), and post-intervention (week 10) of Phase 1, as well as at week 5 and week 10 of Phase 2. Scans will be performed using a standardized protocol by trained technicians. Participants will be instructed to avoid vigorous physical activity and follow pre-assessment guidelines for 24 hours prior to each scan to ensure consistent and reliable measurements.
Time frame: Up to end of study data collection (both stages), i.e., assessed up to 1 year
Average Power (Watts) - Isokinetic Knee Extension Test
This measurement will be assessed in both stages of the study. Power of the knee extensors will be measured using an isokinetic dynamometer during concentric unilateral knee extension at standardized angular velocities. Assessments will be performed at baseline (week 0), mid-intervention (week 5), and post-intervention (week 10) in both phases. All power assessments will be conducted at least 72 hours after the last training session to minimize the effects of fatigue and ensure valid measures of peak performance.
Time frame: Up to end of study data collection (both stages), i.e., assessed up to 1 year
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