Figure 1.

Low muscle quality is characterized by impaired transport of amino acids, especially branched chain amino acids. (A) Metabolomics plasma metabolites are ordered by expression differences between age, sex, and height matched pairs of cases (low muscle quality) and controls (high muscle quality) from the Baltimore Longitudinal of Aging. Participants with low muscle quality presented higher plasma concentrations of most amino acids, particularly isoleucine and leucine, compared with the control group (adapted from Moaddel et al.8) (N= 79 cases and 79 controls). (B) Concentration of BCAAs in biopsy specimens collected from the vastus lateralis was lower in participants with low muscle quality compared with those with high muscle quality (unpublished results) (N= 9 cases and 9 controls). ILE, isoleucine; LEU, leucine; VAL, valine; BCAA, branched chain amino acids.