The interaction of competition and terrain on pacing during cross-county running races in junior athletes

The aim of this study was to assess pacing during cross-country racing in relation to race length, surface-terrain and racing dynamics. Athletes (n = 148) competed for school teams (U15, U17, U20) over 2.9, 4.2, 6.3 km, respectively. The course lap (2.067 m) was timed using UHF-RFID and divided into six sections based on surface-terrain and length (549, 619, 207, 338, 150, 156m). Overall pace differed between races (4.56 ± 0.30, 4.42 ± 0.38, 4.40 ± 0.31 m∙s^-1, p=0.042) but not for the top-20 of each race (p=0.174). Moreover, within lap pacing followed a repeated reverse-"J"-parabolic strategy for all races. Race length (no. of laps) and category affected pacing with regards to finish position banding (1st-10th, 11th-20th) where effect size differences showed large to extremely large (1.21 - >4.00) difference between top-10 and other bands. Exceptions to this included the finish sprint where it was typically trivial-moderate (<0.2-1.2) and in key areas where social facilitation occurred. Athlete/coaches need to be aware of between and within lap variations in pace/effort, the effects of race dynamics, and spectator influences, while all athletes need to be educated as part of their training to run their own optimal strategy for best performance.