Performance in endurance sports decreases with aging, which has been primarily attributed to cardiovascular and musculoskeletal aging; however, there is still no clear information on the factors that are most affected by aging. The aim of this study was to compare two groups of runners (< 50 and > 50 years of age) according to their absolute, weight-adjusted maximal oxygen uptake (V̇O2max), lower limb lean mass-adjusted V̇O2max, ventilatory threshold, and respiratory compensation point (RCP). A total of 78 male recreational long-distance runners were divided into Group 1 (38.12 ± 6.87 years) and Group 2 (57.55 ± 6.14 years). Participants were evaluated for body composition, V̇O2max, VT, and RCP. Group 1 showed higher absolute and body mass-adjusted V̇O2max(4.60 ± 0.57 l·min−1and 61.95 ± 8.25 ml·kg−1·min−1, respectively) than Group 2 (3.77 ± 0.56 l·min−1and 51.50 ± 10.22 ml·kg−1·min−1, respectively), indicating a significant difference (p< 0.001, d =  − 1.46 andp< 0.001, d =  − 1.16). Correspondingly, Group 1 showed a significantly higher lower limb lean mass–adjusted V̇O2max(251.72 ± 29.60 ml·kgLM−1·min−1) than Group 2 (226.36 ± 43.94 ml·kgLM−1·min−1) (p= 0.008, d =  − 0.71). VT (%V̇O2max) (p= 0.19, d = 0.19) and RCP (%V̇O2max) (p= 0.24, d = 0.22) did not differ between the groups. These findings suggest that both variables that are limited by central or peripheral conditions are negatively affected by aging, but the magnitude of the effect is higher in variables limited by central conditions. These results contribute to our understanding of how aging affects master runners.