Department of Kinesiology, Indiana University, Bloomington, IN.
Med Sci Sports Exerc. 2018 May;50(5):1046-1053. doi: 10.1249/MSS.0000000000001515.
Timing foot strike to occur in synchrony with cardiac diastole may reduce left ventricular afterload and promote coronary and skeletal muscle perfusion.
This study aimed to assess heart rate (HR) and metabolic responses to running when foot strikes are timed to occur exclusively during 1) the systolic phase of the cardiac cycle or 2) the diastolic phase.
Ten elite male distance runners performed a testing session on a treadmill at 4.72 m·s while matching their steps to an auditory tone and wearing a chest strap that transmitted accelerometer and ECG signals. Testing comprised eight prompted 3-min stages, where a real-time adaptive auditory tone guided subjects to step with each ECG R-wave (systolic stepping) or alternatively, at 45% of each R-R interval (diastolic stepping), followed by a 3-min unprompted control stage. Metabolic variables were measured continuously.
HR (P < 0.001) and minute ventilation (P < 0.001) were significantly lower during diastolic stepping compared with systolic stepping, whereas O2 pulse (P < 0.001) was correspondingly significantly higher during diastolic stepping.
Synchronizing foot strikes when running to the diastolic portion of the cardiac cycle results in a significantly reduced HR and minute ventilation compared with stepping during systole. This cardiac and ventilatory response to diastolic stepping may be beneficial to distance running performance.
本研究旨在评估在跑步时，足部的着地时刻仅发生在心脏周期的收缩期或舒张期时，心率（HR）和代谢的反应。
10 名男性精英长跑运动员在跑步机上以 4.72m/s 的速度进行测试，同时根据听觉提示与节拍器保持同步，并佩戴胸带以传输加速度计和心电图信号。测试包括 8 个提示的 3 分钟阶段，其中实时自适应听觉提示引导受试者与每个心电图 R 波（收缩期踏足）或相反，与每个 R-R 间隔的 45%（舒张期踏足）同步踏足，随后进行 3 分钟无提示的对照阶段。连续测量代谢变量。
与收缩期踏足相比，舒张期踏足时 HR（P < 0.001）和分钟通气量（P < 0.001）显著降低，而 O2 脉冲（P < 0.001）相应显著升高。
与收缩期踏足相比，在跑步时将足部着地时刻同步到心脏周期的舒张期会导致 HR 和分钟通气量显著降低。这种舒张期踏足的心脏和通气反应可能对长跑表现有益。
