Impact of Aerobic Capacity on Mechanical Variables in Track Sprinters and Middle-Distance Runners: A Comparative Study

<b>Background:</b> This study examined the impact of aerobic capacity on force-velocity (F-v) variables and repeated-sprint (RS) performance in male national-level sprinters (SPRs, <i>n</i> = 8; 177.0 ± 4.3 cm; 74.0 ± 5.0 kg; maximal oxygen uptake [VO₂max]: 55.4 ± 3.0 mL/kg/min) and middle-distance runners (MDRs; <i>n</i> = 8; 179.0 ± 5.1 cm; 67.2 ± 5.0 kg; VO₂max: 64.3 ± 3.3 mL/kg/min). <b>Method:</b> Participants underwent assessments of aerobic capacity, mechanical F-v profiling in sprinting 2 × 60 m with full recovery, and a 10 × 60 m repeated-sprint test with 30 s recovery. <b>Results:</b> MDRs exhibited significantly higher VO₂max (<i>p</i> < 0.001) and speed at VO₂max (vVO₂max, <i>p</i> < 0.001), while SPRs demonstrated greater anaerobic speed reserve (ASR, <i>p</i> < 0.001), maximal theoretical horizontal force (F₀, <i>p</i> = 0.012), and power output (P_max, <i>p</i> < 0.01). During the RS test, SPRs displayed a 16.6% performance decrement (<i>p</i> = 0.002) and failed to complete all sprints with voluntary withdrawal after 5-8 sprints due to exhaustion, whereas MDRs maintained consistent performance. SPRs exhibited a larger decrease in v₀ compared to MDRs (<i>p</i> < 0.01), whereas no differences were observed on F₀ (<i>p</i> = 0.519) and P_max (<i>p</i> = 0.758). Blood lactate accumulation was higher in SPRs (<i>p</i> < 0.001). Multiple linear regression analysis on the pooled sample identified vVO₂max (<i>p</i> = 0.003) and not ASR (<i>p</i> = 0.482) as a key predictor of fatigue resistance. <b>Conclusions:</b> These findings underscore the critical role of aerobic capacity in sustaining RS performance. Aerobic capacity, specifically vVO₂max, emerged as the primary determinant of fatigue resistance during repeated sprints, underscoring its critical role in sustaining RS performance over mechanical variables such as v₀ but not F₀ and P_max.