Amino Muscle Caps, 240 Capsules, Source NaturalsSource Naturals Amino Muscle Branched Chain Amino Acids. Provides Unique Musculoskeletal Support. Amino Muscle provides support to your body's muscular systems with a vigorous blend of branched chain amino acids and supporting B vitamins. Research has shown that during exercise, branched chain amino acids are metabolized directly in the skeletal muscle a process that provides robust musculoskeletal fortification when your body needs it the most.