Speed endurance, maximal sprint speed, and stride characteristics in well-trained 800-m runners

Introduction Recent studies have focused on maximal sprint speed (MSS) and aerobic speed (e.g., v V̇ O 2 peak); however, their associations with speed endurance and high-speed stride characteristics relevant to 800‑m performance remain unclear. We aimed to examine the associations among MSS, speed-endurance-related measures, v V̇ O 2 peak, and 800‑m performance and to clarify step frequency (SF) and step length (SL) characteristics during high-speed sprinting. Methods Twenty-one well-trained male 800‑m runners participated (season-best 800‑m time, 116.67 ± 4.57 s). 800‑m performance was expressed as season-best mean speed (v800). MSS was assessed using a 60‑m sprint, v40sec was defined as the mean speed during a 40‑s sprint and used as a speed-endurance-related measure, and v V̇ O 2 peak was assessed using an incremental test. SF and SL were measured at MSS and during the 40‑s sprint. Results v40sec correlated with v800 in simple (r = 0.77, p < 0.001) and partial analyses (r = 0.67, p = 0.001). MSS correlated with v800 (r = 0.54, p = 0.012); however, this association was no longer significant after controlling for v40sec. Regression analysis identified v40sec and v V̇ O 2 peak as predictors of v800 (adjusted R 2 = 0.75). v800 positively correlated with SL40sec across all segments after controlling for height. Conclusions Although MSS was associated with 800‑m performance in simple correlation analyses, this association was attenuated after controlling for v40sec, whereas v40sec remained associated with performance. These findings suggest that the MSS–performance association may partly reflect variance shared with v40sec, a speed-endurance-related measure. SL characteristics at high sprint speeds may be related to performance.