Effects of a leucine-enriched amino acid supplement on muscle mass, muscle strength, and physical function in post-stroke patients with sarcopenia: A randomized controlled trial

Objectives: The aim of this study was to investigate the effects of a leucine-enriched amino acid supplement on muscle mass, muscle strength, and physical function in post-stroke patients with sarcopenia.

Methods: We conducted an eight-wk, two-parallel group intervention, randomized controlled, blinded outcome assessment among 44 post-stroke older patients with sarcopenia. Sarcopenia was defined as a loss of skeletal muscle mass and decreased muscle strength according to the Asian Working Group for Sarcopenia criteria. The intervention group (n = 21) received a leucine-enriched amino acid supplement; the control group (n = 23) did not. Both groups performed low-intensity resistance training in addition to a post-stroke rehabilitation program. A primary outcome of physical function by using the motor domain of Functional Independence Measure (FIM), and secondary outcomes of appendicular muscle mass (skeletal muscle mass index [SMI]) measured via bioelectrical impedance analysis and muscle strength as handgrip strength were measured at baseline and at the end of the intervention.

Results: The FIM score increased significantly in both groups over time (P < 0.01), with significantly greater improvement in the intervention group than in the control group (P < 0.045). Handgrip strength also increased significantly over time (P <0.05), with significantly greater improvement in the intervention group (P < 0.01). The SMI increased significantly in the intervention group but not in the control group over time, with significantly greater improvement in the intervention group (median estimated difference, 0.50 kg/m²; 95% confidence interval, 0.01-2.11).

Conclusions: We demonstrated that an eight-wk intervention consisting of a leucine-enriched amino acid supplementation and low-intensity resistance training increased muscle mass, strength, and physical function in post-stroke patients with sarcopenia.