Datasheet1_Discovering the sluggishness of triathlon running - using the attractor method to quantify the impact of the bike-run transition.pdf

Running in a triathlon, a so-called brick run, is uniquely influenced by accumulated load from its preceding disciplines. Crucially, however, and irrespective of race type, the demands of a triathlon always exceed the sum of its parts. Triathletes of all levels commonly report subjectively perceived incoordination within the initial stages of the cycle run transition (T2). Although minimizing it, and its influence on running kinematics, can positively impact running and overall triathlon performance, the mechanisms behind the T2 effect remain unclear. In the present study, we assessed the influence of the pre-load exercise mode focusing on the biomechanical perspective. To analyze inertial sensor-based raw data from both legs, the so-called Attractor Method was applied. The latter represents a sensitive approach, allowing to quantify subtle changes of cyclic motions to uncover the transient effect, a potentially detrimental transient phase at the beginning of a run. The purpose was to analyze the impact of a pre-load on the biomechanics of a brick run during a simulated Olympic Distance triathlon (without the swimming section). Therefore, we assessed the influence of pre-load exercise mode on running pattern (δM) and precision (δD), and on the length of the transient effect (tT) within a 10 km field-based run in 22 well-trained triathletes. We found that δD, but not δM, differed significantly between an isolated run (IRun) and when it was preceded by a 40 km cycle (TRun) or an energetically matched run (RRun). The average distance ran until overcoming the transient phase (tT) was 679 m for TRun, 450 m for RRun, and 29 4 m for IRun. The results demonstrated that especially the first kilometer of a triathlon run is prone to an uncoordinated running sensation, which is also commonly reported by athletes. That is, i) the T2 effect appeared more linked to variability in running style than to running style per se ii) run tT distance was influenced by preceding exercise load mode, being greater for a TRun than for the RRun condition, and iii) the Attractor Method seemed to be a potentially promising method of sensitively monitoring T2 adaptation under ecologically valid conditions.

铁人三项中的换项跑步（brick run），即自行车项目结束后即刻接续的跑步环节，其运动表现会显著受此前项目的累积负荷影响。至关重要的是，无论赛事类型如何，铁人三项的整体运动需求始终大于各单项需求的总和。各级别铁人三项运动员均普遍报告，在自行车转跑步的转换区2（Transition 2，T2）初始阶段，会主观感知到肢体协调性下降。尽管尽可能减轻该现象及其对跑步运动学的负面影响，可对跑步表现及整体铁人三项成绩产生积极作用，但T2效应背后的机制仍不明晰。本研究从生物力学视角出发，评估了前置负荷运动模式对换项跑步的影响。为分析双腿基于惯性传感器（inertial sensor）采集的原始数据，本研究采用了吸引子法（Attractor Method）。该方法是一种高灵敏的分析手段，可量化周期性运动的细微变化，以揭示瞬态效应——即跑步初始阶段存在的潜在有害瞬态阶段。本研究旨在分析模拟奥运标准距离铁人三项（不含游泳项目）中，前置负荷对换项跑步生物力学特征的影响。为此，我们对22名受过良好训练的铁人三项运动员，在10公里场地跑步测试中，分别评估了前置负荷运动模式对跑步模式（δM）、精准度（δD）以及瞬态效应时长（tT）的影响。研究发现，跑步精准度（δD）而非跑步模式（δM），在孤立跑步组（IRun）、前置40公里自行车骑行的换项跑步组（TRun）与能量匹配前置跑步组（RRun）之间存在显著差异。各组克服瞬态效应前的平均跑步距离（tT）分别为：换项跑步组679米、前置跑步组450米、孤立跑步组294米（原文中“29 4 m”为排版空格导致的格式误差，实际应为294米）。研究结果表明，铁人三项跑步的首公里尤其容易出现运动员普遍报告的协调性下降问题。具体而言：其一，T2效应与跑步风格的变异性关联更为紧密，而非跑步风格本身；其二，瞬态效应的跑步距离（tT）受前置负荷运动模式影响，换项跑步组的该距离显著长于前置跑步组；其三，吸引子法似乎是一种在生态效度符合实际场景的实验条件下，灵敏监测T2适应性变化的极具潜力的手段。