Relation between change in exercise capacity and change in blood amino acids in patients with chronic heart failure

[Purpose] Although cardiac rehabilitation (CR) is recommended for patients with chronic heart failure (CHF), adequate exercise effect cannot be obtained in elderly patients. Administration of amino acids (AA) to CHF patients has been reported to improve exercise capacity, but the changes in AA composition in plasma before and after CR had not been reported. This study aimed to measure plasma levels of AA in CHF patients and compare with values of normal range. In addition the relationship between the change of exercise capacity and AA were examined. [Subjects and Methods] Twelve CHF patients (60% males, aged 68 ± 12 years) were studied. The correction between the rates of changes in exercise capacity parameters and in plasma AA levels was investigated. [Results] Anaerobic threshold (AT) and peak oxygen uptake (VO₂) improved significantly after CR. The AA profile showed no specific pattern, and citrulline (Cit) was the amino acid showing a significant positive correlation with exercise capacity (∆Cit vs. ∆AT: r=0.602, ∆Cit vs. ∆AT-work rate (WR): r=0.681, ∆Cit vs. ∆VO₂/WR: r=0.635). A tendency of positive correlation was observed between ∆Cit and ∆peak VO₂ (r=0.456). [Conclusion] The AA profile showed no specific pattern, but a relationship between change in exercise capacity and Cit were found.