Cluster Training plus creatine supplementation on body composition and physical performance in older adults: A study protocol

BACKGROUND: Resistance training (RT) is a widely used strategy to improve strength in older adults and counteract age-related decline. Combining RT with creatine monohydrate (CrM) supplementation has been shown to enhance exercise-induced improvements in muscle status and physical performance in this population. Cluster-set resistance training (CS-RT) is a relatively recent approach that has not yet been explored in combination with CrM supplementation in this population. Thus, this study aims to investigate the effects of an 8-week CS-RT program with and without CrM supplementation on body composition and physical performance in older adults. METHODS: Thirty-six older adults over 60 years of age, with no prior RT experience, will be randomly assigned to one of three groups: CS-RT+CrM (n = 12, 0.1 g·kg⁻(1)·day⁻(1) of CrM), CS-RT without CrM supplementation (n = 12), and a control group (CG) maintaining usual daily activities. The 8-week CS-RT program will include three sessions per week with 48 hours of rest between sessions. Each session will consist of three sets of 3 blocks × 4 repetitions at 75% of 1RM, with 30-second intra-set rest and 2-minute rest intervals between sets and exercises (lower limbs: half squat, leg extension, leg press, calf raise; upper limbs: chest press, lat pulldown, shoulder press, biceps/triceps curls). Concentric repetitions will be performed at maximal intended velocity. Body composition will be assessed using dual-energy X-ray absorptiometry (DXA), physical performance with the Short Physical Performance Battery (SPPB), and maximal strength using a one-repetition maximum (1RM) test following ACSM and NSCA guidelines. Statistical analysis will include an ANCOVA with pre-test scores as a covariate, followed by post hoc tests and effect size calculations. Additionally, a difference-in-differences estimation approach will be employed to assess changes over time, with statistical significance set at p < 0.05. RESULTS: We hypothesize that CS-RT+CrM will result in greater improvements on body composition (reduction of fat mass and increase of fat-free mass), physical performance, and maximal strength compared to CS-RT alone. This clinical trial was approved by the Academic Unit of the Postgraduate and Research Department of the Autonomous University of Baja California – Tijuana Campus, Mexico (Code: 340/4188).