One half of the sprinting coin: the oxygen transport cascade of a 91-yr-old female world-record sprinter.

A 91-yr-old female set the W90+ world record in the 200-m sprint in 2024, surpassing her previous record by 1.13 s. This study characterized her cardiorespiratory fitness, skeletal muscle oxidative capacity, fiber-type distribution, capillarization, and satellite cells and compared these outcomes, where possible, to published reference data. Cardiorespiratory responses were assessed during a ramp cycling test to exhaustion, and muscle oxidative capacity (mV̇o2) was determined using near-infrared spectroscopy during repetitive arterial occlusions. Fiber-type distribution, cross-sectional area, capillarization, satellite cell content and localization, and mitochondrial respiratory capacity were analyzed in a vastus lateralis biopsy. Peak oxygen uptake (V̇o2peak) was 23 mL·kg-1·min-1 at 98 W, with a maximal heart rate of 141 beats·min-1 and cardiac output of 13.6 L·min-1. The mV̇o2 recovery rate constant (k) was 1.83 min-1. Fiber composition was 57% fast MyHC II fibers (50% IIa, 5% IIa-IIx, and 2% IIx), 38% slow MyHC I fibers, and 5% hybrid I-IIa fibers. MyHC I fibers were larger, more vascularized, and had satellite cells located closer to capillaries [4,267 ± 2,181 μm2; 1.67 individual capillary-to-fiber ratio (C/Fi), 5.58 capillaries × 1,000 μm-1 capillary-to-fiber perimeter exchange index (CFPE), 1.8-µm satellite cell-to-capillary distance] than MyHC II fibers (2,752 ± 1,608 μm2; 1.03 C/Fi, 4.00 capillaries × 1,000 μm-1 CFPE and 10.4 µm, respectively). Mitochondrial O2 flux was 58 and 68 pmol·(s·mg)-1 during coupled and uncoupled respiration, respectively. The athlete's cardiorespiratory and oxidative capacity resembled those of females in their 50s or younger. Collectively, her large, well-vascularized slow fibers, high proportion of fast fibers, and preserved muscle oxidative capacity likely contributed to her world record performance, illustrating the remarkable plasticity of skeletal muscle even in very advanced age.NEW & NOTEWORTHY We report an in vivo and ex vivo characterization of cardiorespiratory fitness and muscle oxidative capacity in a 91-yr-old female who holds the W90+ 200-m world record. She exhibited a high muscle oxidative capacity and a muscle fiber profile with large, well-vascularized slow fibers and a relatively high proportion of fast fibers. These findings suggest that components of the oxygen transport and utilization system can be well-preserved into very advanced age in a lifelong sprinter.