Effects of 5-aminolevulinic acid with iron supplementation on respiratory responses to graded cycling and interval walking training achievement in older women over 75 yrs.

Abstract Background Exercise training above a given intensity is necessary to prevent age-associated physical disability and diseases; however, the physical and psychological barriers posed by deteriorated physical fitness due to aging may hinder older people from performing daily exercise training. Because 5-aminolevulinic acid (ALA), a precursor of heme, reportedly improves mitochondrial function, we examined whether ALA, combined with sodium ferrous citrate (SFC) for enhancement, improved aerobic capacity and voluntary exercise training achievement in older women aged over 75 yrs. Methods The study was conducted using a placebo-controlled, double-blind crossover design. Fifteen women aged ~78 yrs. with no exercise habits underwent two trials for 7 days each where they performed interval walking training (IWT), repeating fast and slow speeds of walking for 3 min each, at >70% and at ~40% of peak aerobic capacity for walking, respectively, with ALA+SFC (100 and 115 mg/day, respectively) or placebo supplement intake (CNT), with a 12-day washout period. Before and after each trial, subjects underwent a graded cycling test while having their oxygen consumption rate (VO2), carbon dioxide production rate (VCO2), and plasma lactate concentration ([Lac−]p) measured. Furthermore, during the supplement intake period, exercise intensity for IWT was measured by accelerometry. Results In ALA+SFC, the increases in VO2 and VCO2 during the graded cycling test were attenuated (both, P   0.46). Furthermore, energy expenditure and time during fast walking for IWT were 25% (P = 0.032) and 21% (P = 0.022) higher in ALA+SFC than in CNT. Conclusion Thus, ALA+SFC supplementation improved aerobic capacity and thus increased fast-walking training achievement in older women.