Better race times without higher VO2peak: performance gains in recreational runners over 18 months

Background / Introduction Performance improvement in endurance running is commonly attributed to increases in peak oxygen consumption (VO₂peak) and central cardiopulmonary adaptations. However, the relative contribution of ventilatory thresholds and submaximal efficiency to performance gains in recreational athletes remains unclear. Purpose To determine whether improvements in 5-km race performance over 18 months are associated with changes in VO₂peak and other CPET-derived central parameters in recreational runners. Methods We conducted a prospective longitudinal study including 44 healthy recreational runners (19 women), aged 18–41 years, followed for 18 months. Cardiopulmonary exercise testing (CPET) was performed at baseline and at months 6, 12, and 18, one week prior to standardized 5-km urban races. Only athletes demonstrating >1-minute improvement per race were included. Variables analyzed included VO₂peak, VE/VCO₂ slope, oxygen pulse, ventilatory thresholds, and weekly training load (MET-min/week). Repeated-measures analysis and correlation testing were performed. Statistical significance was defined as p<0.05. Results Race performance improved progressively: 3.6% (±1.1), 5.1% (±0.6), and 7.9% (±2.9) across intervals (p<0.001 for trend). VO₂peak showed minimal changes: 0.6%, 0.2%, 0.5%, and 0.4% across evaluations (NS). No significant correlation was observed between race time improvement and VO₂peak change, either individually or in pooled analysis (r≈0, p=NS). VE/VCO₂ slope and oxygen pulse demonstrated negligible variation (Δ ≤0.5, NS). Training load increased progressively (685±68, 709±95, 844±214, 982±315 MET-min/week; p<0.01). In contrast, the first ventilatory threshold increased consistently (4.5%, 6.5%, 9.2%, 13.8%; p<0.001), as did the anaerobic threshold (1.9%, 3.8%, 4.4%, 9.4%; p<0.01). The second ventilatory threshold remained stable (NS). Conclusion In recreational runners, progressive improvement in 5-km performance over 18 months was not associated with meaningful changes in VO₂peak, VE/VCO₂ slope, or oxygen pulse. Performance gains were primarily linked to upward displacement of submaximal ventilatory thresholds, suggesting that improvements in metabolic efficiency and peripheral adaptation, rather than central cardiopulmonary capacity, drive endurance performance enhancement in this population.