A 91-year-old female set the W90+ world record in the 200m sprint in 2024. We characterized her neuromuscular function, fatigability, denervation markers, and single-fiber contractile properties, and, where possible, compared these outcomes to published reference data. Knee extensor muscle architecture, force, power, fatigability, and motor unit (MU) behavior were assessed in vivo, and a vastus lateralis biopsy was analyzed for single-fiber contractile properties and markers of denervation. Quadriceps cross-sectional area was 36.5cm², with fascicle length, pennation angle, and muscle thickness of 6.7cm, 11.6°, and 1.4cm, respectively. Knee extensor MVIC was 79Nm, power was 28W, and power declined by 43% during a 4-min fatiguing task. MU recruitment threshold was 12±11% of MVIC. Single-fiber absolute and specific-force were 0.88±0.19mN and 114±10kN/m² for myosin heavy chain (MyHC) I, and 0.74±0.23mN and 171±23kN/m² for MyHC IIa fibers. Less than 1% of fibers were positive for the denervation marker NCAM, no fibers expressed embryonic MyHC, and ~1% of MyHC II fibers expressed neonatal MyHC. In vivo muscle size, force, power, and fatigability were largely within the range for individuals one decade younger. MU behavior was comparable to individuals 20 years younger. MyHC I fiber absolute force exceeded values reported in untrained young females and females in their eighth decade whereas MyHC II fiber force was lower due to smaller fiber size. Denervation markers were less prevalent than typically reported at this age. Collectively, these findings illustrate the heterogeneous effects of aging on different features of neuromuscular function, even in an elite older female sprint athlete.
Colosio et al. (Wed,) studied this question.