Hamzaid Nur Azah, Pithon Karla R, Smith Richard M, Davis Glen M
Clinical Exercise and Rehabilitation Unit, Faculty of Health Sciences, The University of Sydney, Australia.
Clin Biomech (Bristol). 2012 Aug;27(7):731-7. doi: 10.1016/j.clinbiomech.2012.03.005. Epub 2012 Apr 18.
The cardiorespiratory responses and mechanical efficiencies of two modalities of functional electrical stimulation augmented leg exercises - isokinetic cycling and isokinetic elliptical stepping - were compared amongst individuals with spinal cord injury.
Five subjects performed seated isokinetic evoked cycling and elliptical stepping leg exercise at 10, 20 and 30rev·min(-1) pedal cadences. 3-D motion analysis and force transducers attached onto the foot pedals quantified the external forces and power outputs developed by each lower extremity. Hip, knee and ankle joints power were derived via inverse dynamics analysis. The subjects' cardiorespiratory responses during exercise were measured by respiratory gas analysis.
Ensemble-averaged oxygen uptakes across pedal cadences were higher during stepping (448 (75) ml·min(-1)) compared to cycling (422 (54) ml·min(-1)). External power outputs and metabolic efficiencies during stepping (9.9 (8.3) W, 2.9 (3.2) %) were double those observed during cycling (5.3 (6.3) W, 1.6 (1.9) %). Cumulative internal and external leg joint powers during stepping were twice higher than cycling, but the stepping mechanical efficiencies derived from inverse dynamics analysis were comparable to cycling (76.3 (21.2) % and 63.6 (12.3) % respectively). Heart rate responses were similar between cycling and stepping, while carbon dioxide production and expired ventilation were slightly higher during elliptical stepping.
Both exercise modalities could deliver appropriate training stimuli for improving the aerobic fitness and leg pedalling strength of spinal cord-injured individuals. However electrical stimulation-enhanced elliptical stepping might provide greater exercise dose-potency for leg muscle strengthening than electrically-enhanced cycling due to the higher power outputs observed.
在脊髓损伤患者中比较了两种功能性电刺激增强腿部运动方式（等速骑行和等速椭圆踏步）的心肺反应和机械效率。
五名受试者以每分钟10、20和30转的踏板节奏进行坐姿等速诱发骑行和椭圆踏步腿部运动。三维运动分析和安装在脚踏板上的力传感器量化了每个下肢产生的外力和功率输出。通过逆动力学分析得出髋、膝和踝关节的功率。运动期间受试者的心肺反应通过呼吸气体分析进行测量。
与骑行（422（54）毫升·分钟⁻¹）相比，踏步期间各踏板节奏下的总体平均摄氧量更高（448（75）毫升·分钟⁻¹）。踏步期间的外部功率输出和代谢效率（9.9（8.3）瓦，2.9（3.2）%）是骑行期间观察值的两倍（5.3（6.3）瓦，1.6（1.9）%）。踏步期间腿部关节的累积内、外功率比骑行高两倍，但通过逆动力学分析得出的踏步机械效率与骑行相当（分别为76.3（21.2）%和63.6（12.3）%）。骑行和踏步期间的心率反应相似，而椭圆踏步期间的二氧化碳产生量和呼气通气量略高。
两种运动方式都可以为改善脊髓损伤患者的有氧适能和腿部蹬踏力量提供适当的训练刺激。然而，由于观察到更高的功率输出，电刺激增强的椭圆踏步可能比电刺激增强的骑行在增强腿部肌肉方面提供更大的运动剂量效能。
