Fat infiltration and muscle hydration improve after high-intensity resistance training in women with sarcopenia. A randomized clinical trial.

BACKGROUND: Resistance training is recommended for preventing sarcopenia, but the benefits for the quality and quantity of muscle mass are uncertain. OBJECTIVE: To assess the effects of high-intensity resistance training (HIRT) on clinical and magnetic resonance imaging (MRI) parameters in women with sarcopenia. METHODS: A researcher-blinded randomized clinical trial was conducted. Community-dwelling older women with sarcopenia were randomized to six months of HIRT or a control group (CG). Body composition was assessed with bioimpedance equipment, and participants underwent strength and functional performance tests (short physical performance battery [SPPB] and gait speed). MRI scans of the thigh were taken to quantify muscle mass and quality. RESULTS: Thirty-eight women completed the study (20 in the HIRT group). Sarcopenia remitted in 50 % of the HIRT group. HIRT elicited a significant group × time interaction effect for muscle mass (p = 0.027; È 2 = 0.129), muscle mass index (p = 0.023; È 2 = 0.135), fat mass (p = 0.048; È 2 = 0.103) and all strength variables (p < 0.05; È 2 > 0.120). Moreover, the HIRT group obtained higher scores on the SPPB (mean difference [MD] 1.2; p = 0.005) and the 5 times sit-to-stand test (MD = 0.7; p = 0.009). Regarding MRI parameters, infiltrated microscopic fat decreased significantly (HIRT: MD = -0.01; p < 0.05), while hydration (T2) decreased in the CG (MD = 3.6 ms; p = 0.053) at six months. There were significant between-group differences at six months for water diffusion (HIRT: 1.09 × 10-3 mm2/s vs CG: 1.26 × 10-3 mm2/s) and total muscular volume (HIRT: 832.4 L vs CG: 649.2 L). CONCLUSIONS: HIRT led to the remission of sarcopenia in half of the older women, as seen in muscle mass, strength, and functional performance and MRI biomarkers, with significant increases in muscle quality. REGISTERED IN CLINICALTRIALS.GOV: NCT03834558.