Author(s): COMINO, P., WALT, M., CASADO, A., Institution: REY JUAN CARLOS UNIVERSITY, Country: SPAIN, Abstract-ID: 2256

INTRODUCTION:
Pacing refers to how athletes regulate effort and energy expenditure throughout a competitive event (1). In the 400-m event, performance typically shows a progressive decrease in speed, largely attributed to metabolic and neuromuscular constraints (2). However, race dynamics vary according to the competitive season, as events are held on indoor (200-m) or outdoor (400-m) tracks: indoor competitions involve lane merging during the second half of the race, whereas outdoors are completed entirely in separate lanes. This structural distinction increases tactical complexity indoors, as athletes must directly interact with opponents in the latter stages of the race (3). However, existing evidence in this area is limited to outdoor competitions. Therefore, this study aimed to directly compare pacing patterns and intermediate positioning between indoor and outdoor World Championship 400-m races.
METHODS:
Official electronic 100-m section times were obtained from 73 World Championship 400-m races, categorized as indoor (200-m) or outdoor (400-m). A total of 494 performances were analyzed and classified by result: Qualified (Q) or Non-Qualified (NQ) in heats and semifinals, and Medallists (M) or Non-Medallists (NM) in finals. For each athlete, 100-m section speeds and intermediate positions were recorded. Pearson correlations between intermediate and final positions, along with pacing profiles and the coefficient of variation of pace (CV%), were calculated and compared between track types.
RESULTS:
Differences in CV% were observed between indoor and outdoor races in heats (Q and NQ groups) and semifinals (Q group) with higher values recorded indoors (p < 0.01; d = 0.79–1.59). Pacing strategies in indoor races were characterized by a higher initial speed during the first 100-m section, followed by a greater speed decline in the second half of the race. This pattern was consistent across all competition phases. Intermediate positions were very highly correlated with final position from the 100-m section onwards (r ≥ 0.90), except in outdoor finals, where the strength of the correlation increased progressively throughout the race (r = 0.62–0.94).
CONCLUSION:
Pacing strategies differ between indoor and outdoor 400-m events. Indoor races feature a faster start, followed by a greater speed decline in the second half, likely reflecting the need to secure position before lane merging. In contrast, outdoor races are paced more evenly, as athletes remain in their own lanes, allowing a more efficient distribution of effort. Intermediate positions become highly predictive of final outcome from the first 100-m split in heats and semifinals. In outdoor finals, however, this association strengthens progressively, reflecting the greater competitive density at this stage of the Championship.