Exploring the physiological limits of aging: a case study of the male 50-km world record in the 80+ age category

UNLABELLED: Aging is associated with declines in cardiorespiratory fitness and endurance performance, but this association is usually confounded by age-related declines in physical activity levels. For this reason, world-class master athletes serve as exceptional models for elucidating the limits of endurance performance in old age. PURPOSE: To examine the physiological responses to exercise and performance characteristics of an 81-year-old male runner who, in 2025, set a new world record in the 50-km race (4h47m39s, 10.5 km h⁻¹) in the 80+ category. METHODS: Two weeks after the world record, maximal O₂ uptake ( V ˙ O2max), fractional utilization of V ˙ O2max (lactate threshold [LT]), maximal fat oxidation (MFO) and running economy (RE) were assessed through incremental running tests. Limiting factors to V ˙ O2peak were assessed during incremental cycling exercise by gas exchange, peak cardiac output (Q̇peak), and peak fractional O₂ extraction of the vastus lateralis (VL) muscle. In vivo VL muscle oxidative capacity and relative resistance to O₂ diffusion were estimated using near-infrared spectroscopy (NIRS) during repeated transient arterial occlusions in well-oxygenated (kHIGH) and low O₂ availability (kLOW) conditions. RESULTS: V ˙ O2max was 52.8 mL kg⁻¹·min⁻¹, achieved at 13.2 km h⁻¹. LT was attained at 10.5 km h⁻¹. MFO was 0.55 g·min⁻¹ occurring at 84% of V ˙ O2max and RE was 237.5 mL kg⁻¹·km⁻¹. Cycling V ˙ O2peak was 2.510 L min⁻¹ (42.6 mL kg⁻¹·min⁻¹), Q̇peak was 15.3 L min⁻¹, and arterial-venous O₂ difference was 16.4 mL dl⁻¹, comparable to fractional O₂ extraction around 75% obtained by NIRS. kHIGH was 4.67 min⁻¹ and kLOW was 4.59 min⁻¹, suggesting high oxidative and muscle O₂ diffusing capacity. CONCLUSION: The exceptional endurance performance of this master athlete was attributed to his well-preserved V ˙ O2max (to our knowledge the highest recorded in octogenarians, equivalent to the 70th percentile for healthy males aged 20-30 years) and a high fractional utilization of V ˙ O2max, together with a great ability to oxidize fats. Analyses on the limiting factors to V ˙ O2max suggest that his exceptional performance was mostly due to the final steps of the oxygen cascade.