Pacing during an ultramarathon running event in hilly terrain

Purpose. The dynamics of speed selection as a function of distance, or pacing, are used in recreational, competitive, and scientific research situations as an indirect measure of the psycho-physiological status of an individual. The purpose of this study was to determine pacing on level, uphill and downhill sections of participants in a long (~173 km) ultramarathon performed on trails in hilly terrain. Methods. Fifteen ultramarathon runners competed in a ~173 km event (five finished at ~103 km) carrying a Global-Positioning System (GPS) device. Using the GPS data, we determined the speed, relative to average total speed, in level (LEV), uphill (UH) and downhill (DH) gradient categories as a function of total distance, as well as the correlation between overall performance and speed variability, speed loss, and total time stopped. Results. There were no significant differences in normality, variances or means in the relative speed in 173-km and 103-km participants. Relative speed decreased in LEV, UH and DH. The main component of speed loss occurred between 5% and 50% of the event distance in LEV, and between 5% and 95% in UH and DH. There were no significant correlations between overall performance and speed loss, the variability of speed, or total time stopped. Conclusions. Positive pacing was observed at all gradients, with the main component of speed loss occurring earlier (mixed pacing) in LEV compared to UH and DH. A speed reserve (increased speed in the last section) was observed in LEV and UH. The decrease in speed and variability of speed were more important in LEV and DH than in UH. The absence of a significant correlation between overall performance and descriptors of pacing is novel and indicates that pacing in ultramarathons in trails and hilly terrain differs to other types of running events.目的：作为距离函数的速度选择动态变化（即配速（pacing）），可在休闲、竞技及科学研究场景中作为评估个体心理生理状态的间接指标。本研究旨在针对一项在丘陵地形越野步道开展的约173公里超级马拉松（ultramarathon）赛事，分析参赛者在平路、上坡及下坡路段的配速情况。 方法：共有15名超级马拉松跑者参与了约173公里的赛事（其中5名参赛者完成了约103公里赛程），并佩戴了全球定位系统（Global-Positioning System, GPS）设备。基于该设备采集的数据，本研究以总平均速度为基准，计算了平路（LEV）、上坡（UH）及下坡（DH）坡度类别下的相对速度随总赛程的变化情况，并分析了整体完赛成绩与速度变异性、速度损失及总停跑时间之间的相关性。 结果：173公里组与103公里组参赛者的相对速度在正态性、方差及均值方面均无显著差异。平路、上坡及下坡的相对速度均呈下降趋势。平路组的速度损失主要发生在赛事赛程的5%~50%区间，而上坡及下坡组则为5%~95%区间。整体完赛成绩与速度损失、速度变异性及总停跑时间均无显著相关性。 结论：所有坡度下均呈现正配速特征，且与上坡、下坡组相比，平路组的速度损失主要发生阶段更早（混合配速（mixed pacing））。平路及上坡组均存在速度储备（即赛事最后阶段速度提升）。平路及下坡组的速度下降与速度变异性变化较上坡组更为显著。整体完赛成绩与配速特征指标间无显著相关性这一结果具有创新性，表明丘陵地形越野超级马拉松的配速模式与其他类型跑步赛事存在差异。