Department of Physical Therapy, School of Health Sciences, Shinshu University, Nagano, Japan; Department of Rehabilitation Medicine, Tokyo Bay Rehabilitation Hospital, Chiba, Japan.
Department of Rehabilitation Medicine, Tokyo Bay Rehabilitation Hospital, Chiba, Japan.
Ann Phys Rehabil Med. 2021 Mar;64(2):101465. doi: 10.1016/j.rehab.2020.101465. Epub 2021 Feb 8.
Oxygen uptake (V˙O) kinetics at the onset of exercise is slower in patients with stroke than in healthy adults. However, little is known about the cardiorespiratory mechanisms underlying the impaired V˙O kinetics.
This study aimed to investigate the relative effect of impaired oxygen delivery and utilisation on V˙O kinetics at the onset of submaximal exercise in patients with stroke by comparing the time constants of cardiac output (τCO) and V˙O (τV˙O). In addition, we aimed to examine the association between the kinetics of cardiorespiratory variables and functional outcomes.
We included 21 patients with stroke (15 males, mean [SD] age 58.7 [9.5] years, mean days post-stroke 67.9 [30.9]). A submaximal constant-load exercise test was performed to measure τV˙O, τCO, and the time constant of arterialvenous oxygen difference (τAVOdiff). The ratio of τCO to τV˙O was calculated to assess the matching of oxygen delivery and consumption. Fugl-Meyer lower-extremity motor scores, comfortable gait speeds, and Functional Independence Measure motor scores were used as functional variables.
Mean (SD) τAVOdiff was markedly shorter than τV˙O and τCO (26.1 [7.1] vs. 38.7 [10.2] and 46.6 [23.2 s], P<0.05), with no significant difference between τV˙O and τCO (P=0.444). The greater ratio of τCO to τV˙O was related to poorer motor function (rho=-0.484, P=0.026) and slower comfortable gait speed (r=-0.482, P=0.027).
An increase in CO was slower than that in AVOdiff in patients with stroke. Therefore, V˙O kinetics in patients with stroke appears to be affected by a delayed increase in CO rather than AVOdiff. Furthermore, these patients with motor and gait impairments may have a poor matching of oxygen delivery and consumption during exercise onset.
与健康成年人相比，中风患者在运动起始时的摄氧量（V˙O）动力学较慢。然而，对于导致 V˙O 动力学受损的心肺机制知之甚少。
本研究旨在通过比较心输出量（τCO）和 V˙O（τV˙O）的时间常数，来探讨中风患者在亚最大运动起始时，氧输送和利用受损对 V˙O 动力学的相对影响。此外，我们还旨在研究心肺变量动力学与功能结局之间的关系。
我们纳入了 21 名中风患者（15 名男性，平均年龄[标准差]为 58.7[9.5]岁，中风后平均天数为 67.9[30.9]天）。进行亚最大恒负荷运动试验以测量 τV˙O、τCO 和动静脉氧差（τAVOdiff）的时间常数。计算 τCO 与 τV˙O 的比值，以评估氧输送和消耗的匹配情况。采用 Fugl-Meyer 下肢运动评分、舒适步行速度和功能性独立测量运动评分作为功能变量。
平均（标准差）τAVOdiff 明显短于 τV˙O 和 τCO（26.1[7.1]与 38.7[10.2]和 46.6[23.2]s，P<0.05），而 τV˙O 与 τCO 之间无显著差异（P=0.444）。较大的 τCO/τV˙O 比值与较差的运动功能相关（rho=-0.484，P=0.026），且与较慢的舒适步行速度相关（r=-0.482，P=0.027）。
中风患者的 CO 增加速度慢于 AVOdiff。因此，中风患者的 V˙O 动力学似乎受 CO 增加延迟的影响，而不是 AVOdiff。此外，这些运动和步态受损的患者在运动起始时可能存在氧输送和消耗的不匹配。
