Background & aims: Aging frequently causes changes in body composition, such as a loss of strength and muscular mass and an increase in fat mass. Exercise training programs have been suggested as effective strategies to mitigate or prevent age-related declines in body composition. Therefore, this study examined the effects of a sixteen-week High-Speed Resistance Training (HSRT) program on body composition parameters in community-dwelling independent older adults.

Methods: The present clinical trial included 79 older adults, who were divided into two groups: intervention group (IG, N = 40, age, 68.50 ± 3.54 years; weight, 68.65 ± 11.36 kg) and control group (CG, N = 39, age, 72.08 ± 5.89 years; weight, 67.04 ± 10.69 kg). IG performed the supervised HSRT for 16 weeks, with 3 sessions per week of 60-70min, each session of 5-6 exercises, 2-3 sets, and 6-10 reps/exercise, while CG did not perform any exercise training program. Body composition parameters were assessed using a multifrequency tetrapolar bioelectrical impedance analyzer (InBody® S10). The level of physical activity and the dietary intake were evaluated by the International Physical Activity Questionnaire (IPAQ-SF) and the Food Frequency Questionnaire, respectively. Statistical analyses were performed using the analysis of covariance (ANCOVA), and effect size (Cohen's d(unbiased)).

Results: The analysis showed significant effects of the group factor for IG on phase angle (F((1)) = 14.39, p < 0.001, η(2)(p) = 0.159). Additionally, results from Δ changes (post-minus pre-values) revealed small and medium effects in favor to IG for body cell mass (t((77)) = 1.21, p = 0.230, d(unb) = 0.27 [-0.17, 0.71]) and phase angle (t((77)) = 2.82, p = 0.006, d(unb) = 0.63 [0.18, 1.08]), respectively.

Conclusions: The HSRT could effectively prevent the decline in cellular health and cell integrity in older adults, as evidenced by the significant improvements in the phase angle. REGISTRATION: Clinicaltrial.gov (ID: NCT05586087).