Stewart J A, Merritt E K, Lidstone D E, McBride J M, Zwetsloot K A
Integrative Muscle Physiology Laboratory, Appalachian State University, ASU Box 32071, Boone, NC, USA.
Biomechanics and Neuromuscular Laboratory, Appalachian State University, ASU Box 32071, Boone, NC, USA.
BMC Sports Sci Med Rehabil. 2022 Aug 1;14(1):149. doi: 10.1186/s13102-022-00543-w.
A significant challenge that non-elite collegiate triathletes encounter during competition is the decline in running performance immediately after cycling. Therefore, the purpose of this study was to determine if performing a 40-km bout of cycling immediately before running would negatively influence running economy and mechanical efficiency of running during simulated race conditions in collegiate triathletes.
Eight competitive club-level collegiate triathletes randomly performed two trials: cycling for 40 km (Cycle-Run) or running for 5 km (Run-Run), immediately followed by a four-minute running economy and mechanical efficiency of running test at race pace on an instrumented treadmill. Blood lactate, respiratory exchange ratio, mechanical work, energy expenditure, and muscle glycogen were also measured during the four-minute running test.
Mechanical efficiency of running, but not running economy, was significantly lower in Cycle-Run, compared to Run-Run (42.1 ± 2.5% vs. 48.1 ± 2.5%, respectively; p = 0.027). Anaerobic energy expenditure was significantly higher in the Cycle-Run trial, compared to the Run-Run trial (16.3 ± 2.4 vs. 7.6 ± 1.1 kJ; p = 0.004); while net (151.0 ± 12.3 vs. 136.6 ± 9.6 kJ; p = 0.204) and aerobic energy expenditure (134.7 ± 12.3 vs. 129.1 ± 10.5 kJ; p = 0.549) were not statistically different between trials. Analysis of blood lactate, respiratory exchange ratio, mechanical work, and changes in muscle glycogen revealed no statistically significant differences between trials.
These results suggest that mechanical efficiency of running, but not running economy, is decreased and anaerobic energy expenditure is increased when a 40-km bout of cycling is performed immediately before running in collegiate triathletes.
非精英大学生铁人三项运动员在比赛中遇到的一个重大挑战是，在骑行后立即出现跑步成绩下降的情况。因此，本研究的目的是确定在大学生铁人三项运动员模拟比赛条件下，在跑步前立即进行40公里的骑行是否会对跑步经济性和跑步机械效率产生负面影响。
八名有竞争力的俱乐部级大学生铁人三项运动员随机进行两项试验：骑行40公里（骑行-跑步组）或跑步5公里（跑步-跑步组），随后立即在装有仪器的跑步机上以比赛配速进行为期四分钟的跑步经济性和跑步机械效率测试。在四分钟的跑步测试期间，还测量了血乳酸、呼吸交换率、机械功、能量消耗和肌肉糖原。
与跑步-跑步组相比，骑行-跑步组的跑步机械效率显著降低，但跑步经济性没有显著差异（分别为42.1±2.5%和48.1±2.5%；p=0.027）。与跑步-跑步组相比，骑行-跑步组的无氧能量消耗显著更高（16.3±2.4与7.6±1.1千焦；p=0.004）；而净能量消耗（151.0±12.3与136.6±9.6千焦；p=0.204）和有氧能量消耗（134.7±12.3与129.1±10.5千焦；p=0.549）在两组之间没有统计学差异。对血乳酸、呼吸交换率、机械功和肌肉糖原变化的分析显示，两组之间没有统计学上的显著差异。
这些结果表明，在大学生铁人三项运动员中，在跑步前立即进行40公里的骑行会降低跑步机械效率，但不会降低跑步经济性，并且会增加无氧能量消耗。
