What pacing strategy 800m and 1500m swimmers use?

Abstract Pacing strategy (PS) has a decisive impact on performance, especially on long-term races.The objective of this study is to characterize the PS used in swimming races of 800m and 1500m freestyle by the finalists of the Olympic trials of the United States, Europe and Brazil,and the Olympic finalists of 2016.Time partials of 63 athletes were analyzed using a decision tree and the CHAID method. The results showed that parabolic was adopted by swimmers of 800m, they start in first lap (29.67 ± 0.88 s), followed by an increase in time (+1.77 s) and a subsequent increase in time (32.04 ± 0.89 s), at the end, the swimmers presented an acceleration,reducing the average of the to 31.44 s. And by the free 1500m swimmers, divided into blocks with a faster average start (29.25 ± 1.15 s), half of the slowest race (30.30 ± 0.76 s), and a new acceleration at the end of the event (29.92 ± 1.12 s), both in the selective Olympic Games and the 2016 and 2016 Olympic final.The worst partials times were observed in the Brazilian Selective (Test Event) (31.11 ± 0.78 s). Medalist, despite presetting the same OS, can sustain a better rhythm throughout he 800m (31.52 ± 1.03 s) and 1500-m (29.80 ± 0.78). We conclude that parabolic PS is the optimal strategy adopted by swimmers of 800-m and 1500m freestyle.摘要：分段配速策略（Pacing Strategy, PS）对运动表现具有决定性影响，尤其在长距离赛事中。本研究旨在刻画美国、欧洲、巴西奥运选拔赛及2016年奥运会决赛选手所采用的800米与1500米自由泳分段配速策略特征。本研究采用决策树与卡方自动交互检测法（Chi-squared Automatic Interaction Detector, CHAID），对63名运动员的分段计时数据开展分析。结果显示，800米自由泳选手普遍采用抛物线型配速策略：首圈用时为29.67±0.88秒，随后单圈用时增加1.77秒，后续单圈用时进一步升至32.04±0.89秒；赛事尾声选手会发起冲刺加速，将平均单圈用时降至31.44秒。1500米自由泳选手的配速则分为三个阶段：以更快的平均起步用时（29.25±1.15秒）开启赛事，中间阶段进入用时最慢的半程区间（30.30±0.76秒），最终在赛事尾声再次发起冲刺加速（29.92±1.12秒）；该配速模式在奥运选拔赛及2016年奥运会决赛选手群体中均有体现。分段计时用时最差的结果出现在巴西奥运选拔赛（测试赛）中，平均用时为31.11±0.78秒。尽管奖牌得主预设的配速策略与其他选手一致（原文疑似笔误，原标识为OS，应为PS），但他们在800米自由泳（31.52±1.03秒）与1500米自由泳赛事中能够维持更稳定的节奏，平均单圈用时分别为31.52±1.03秒与29.80±0.78秒（原文未标注单位，疑似遗漏秒）。本研究最终得出结论：抛物线型配速策略是800米与1500米自由泳选手的最优配速方案。