Muraki Satoshi, Fornusek Ché, Raymond Jacqui, Davis Glen Macartney
Department of Human Living System Design, Faculty of Design, Kyushu University, Japan.
Appl Physiol Nutr Metab. 2007 Jun;32(3):463-72. doi: 10.1139/H07-007.
This study investigated cardiorespiratory responses and muscle oxygenation during prolonged electrical stimulation (ES)-evoked leg cycling in individuals with paraplegia (PARA). Four PARA and 6 able-bodied (AB) persons participated in this study. Subjects performed 10 min of passive cycling and 40 min of active cycling (PARA, ES cycling; AB, voluntary cycling) at workloads selected to elicit an equivalent oxygen uptake between groups. Cycling power output, cardiorespiratory responses, mechanical efficiency, and quadriceps muscle oxygenation (measured with near-infrared spectroscopy) were measured over the duration of the exercise. Oxygen uptake was similar in both groups during active cycling (PARA, 737+/-177 mL.min(-1); AB, 840+/-90 mL.min(-1)). The cycling power output for PARA individuals commenced at 8.8 W, but varied considerably over 40 min. PARA individuals demonstrated markedly lower gross mechanical efficiency (approximately 1.3%) during ES cycling compared with AB individuals performing voluntary exercise (approximately 12.6%). During ES cycling, muscle oxygen saturation (SO2) decreased to approximately 72+/-19%, whereas SO2 during volitional cycling was unaltered from resting levels. Muscle oxygenated haemoglobin initially decreased (-23%) during ES cycling, but returned to resting levels after 10 min. Deoxygenated haemoglobin initially rose during the first 5 min of ES cycling, and remained elevated by 28% thereafter. Upon cessation of ES cycling, lower-limb muscle oxygenation increased (+93%), suggesting reactive hyperaemia in PARA individuals after such exercise. During ES cycling, muscle oxygenation followed a different pattern to that observed in AB individuals performing voluntary cycling at an equivalent VO2. Equilibrium between oxygen demand and oxygen delivery was reached during prolonged ES cycling, despite the lack of neural adjustments of leg vasculature in the paralyzed lower limbs.
本研究调查了截瘫患者（PARA）在长时间电刺激（ES）诱发的腿部骑行过程中的心肺反应和肌肉氧合情况。4名截瘫患者和6名健全人（AB）参与了本研究。受试者在选定的工作量下进行10分钟的被动骑行和40分钟的主动骑行（截瘫患者为ES骑行；健全人为自主骑行），以使两组之间的摄氧量相等。在运动过程中测量骑行功率输出、心肺反应、机械效率和股四头肌氧合（用近红外光谱法测量）。主动骑行期间两组的摄氧量相似（截瘫患者，737±177 mL·min⁻¹；健全人，840±90 mL·min⁻¹）。截瘫患者的骑行功率输出从8.8瓦开始，但在40分钟内变化很大。与进行自主运动的健全人（约12.6%）相比，截瘫患者在ES骑行期间的总机械效率明显更低（约1.3%）。在ES骑行期间，肌肉氧饱和度（SO2）降至约72±19%，而自主骑行期间的SO2与静息水平无变化。在ES骑行期间，肌肉氧合血红蛋白最初下降（-23%），但10分钟后恢复到静息水平。去氧血红蛋白在ES骑行的前5分钟最初升高，此后保持升高28%。ES骑行停止后，下肢肌肉氧合增加（+93%），表明截瘫患者在此类运动后出现反应性充血。在ES骑行期间，肌肉氧合与在相同VO2下进行自主骑行的健全人观察到的模式不同。尽管瘫痪的下肢缺乏腿部血管的神经调节，但在长时间ES骑行期间仍达到了氧需求和氧输送之间的平衡。
