School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK.
The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, USA.
Physiol Rep. 2024 Oct;12(19):e70080. doi: 10.14814/phy2.70080.
This study compared cardiovascular and metabolic responses during concentric and eccentric stepping. Eight participants (5 m, 3f; 22 ± 2 years) performed maximal concentric and eccentric ramp incremental tests on a modified stepping ergometer. Subsequently, three randomized 15-min constant-power tests were performed (1) concentric stepping at 90% of the concentric lactate threshold (LT), (2) eccentric stepping at the same power, and (3) eccentric stepping at the same oxygen uptake (V̇O). At equivalent power (36 ± 6 W, p = 0.62), eccentric stepping resulted in 46 ± 8% lower V̇O, 16 ± 6% lower heart rate (HR), and 11 ± 5% lower mean arterial blood pressure compared to concentric (p < 0.01). Matching V̇O required 65 ± 19% more power during eccentric stepping (p < 0.01). During this test, eccentric V̇O and HR continued to increase, resulting in a 22 ± 29% higher V̇O and 19 ± 16% higher HR in the final minute (p < 0.001). Reduced cardiorespiratory demand during eccentric stepping at the same power as concentric demonstrates a higher eccentric power is required to produce the same V̇O. However, despite being below the concentric LT, eccentric V̇O and HR continued to increase past the predicted steady state, indicating a higher exercise intensity.
这项研究比较了向心和离心踏阶时的心血管和代谢反应。八名参与者（5 男，3 女；22 ± 2 岁）在改良的踏阶式测功仪上进行了最大向心和离心斜坡递增测试。随后，进行了三个随机的 15 分钟恒功率测试：（1）以 90%的向心乳酸阈（LT）进行向心踏阶，（2）以相同功率进行离心踏阶，（3）以相同的摄氧量（V̇O）进行离心踏阶。在等效功率（36 ± 6 W，p = 0.62）下，与向心踏阶相比，离心踏阶导致 V̇O 降低 46 ± 8%，心率（HR）降低 16 ± 6%，平均动脉血压降低 11 ± 5%（p < 0.01）。匹配 V̇O 需要在离心踏阶时增加 65 ± 19%的功率（p < 0.01）。在这个测试中，离心 V̇O 和 HR 继续增加，导致最后一分钟 V̇O 增加 22 ± 29%，HR 增加 19 ± 16%（p < 0.001）。在与向心踏阶相同功率的情况下，离心踏阶的心肺需求降低，表明需要更高的离心功率才能产生相同的 V̇O。然而，尽管低于向心 LT，离心 V̇O 和 HR 继续增加，超过了预测的稳定状态，表明运动强度更高。
