Szecsi Johann, Krause Phillip, Krafczyk Siegbert, Brandt Thomas, Straube Andreas
Center for Sensorimotor Research, Department of Neurology, Ludwig-Maximillians University, Munich, Germany.
Med Sci Sports Exerc. 2007 May;39(5):764-80. doi: 10.1249/mss.0b013e3180334966.
Investigation of the influence of forced smooth and normal (nonsmooth) pedaling on the functional output of outdoor functional neuromuscular electrical stimulation (FES)-propelled cycling of spinal cord-injured subjects.
Twelve subjects with complete spinal cord injury (T4-T12) and limited previous FES training.
Each subject participated in two separate outdoor sessions: once while pedaling a tricycle in a fixed gear, and a second time while free pedaling the same tricycle; both times with FES. Data on distance covered until exhaustion, cadence, and pedal forces were collected. Energy balance calculations led to evaluations of jerk loss and joint-related concentric/eccentric work.
First-trial and total session distances were 68 and 103% longer, respectively, in the forced smooth cycling session than in the free cycling session (P < 0.001). Significantly more additional crank work (accompanied by increased concentric work production) was generated in nonsteady cycling phases to overcome increased jerk losses during free than during fixed-gear pedaling. During fixed-gear pedaling, timing and joint location of muscle work generation were more similar to the cycling of able-bodied subjects than during freewheel pedaling, because most work was generated by knee extensors in the power phase during the former pedaling mode.
The superiority of forced smooth cycling to free cycling, as regards functional output distance, is based on less energy expenditure (less jerk loss and muscle tension) and on more efficient production of energy (more efficient timing and joint location of work production). Some energetic mechanisms that are advantageous for fixed-gear cycling act predominantly in unsteady phases; others work continuously during all phases of cycling.
研究强制平稳骑行和正常（非平稳）骑行对脊髓损伤患者户外功能性神经肌肉电刺激（FES）驱动骑行功能输出的影响。
12名完全性脊髓损伤（T4 - T12）且先前FES训练有限的受试者。
每位受试者参加两次独立的户外测试：一次是在固定档位骑三轮车，另一次是自由骑同一辆三轮车；两次均采用FES。收集直至疲劳时的骑行距离、踏频和踏板力数据。能量平衡计算得出了急动损失和关节相关的向心/离心功的评估结果。
在强制平稳骑行测试中，首次测试和整个测试阶段的骑行距离分别比自由骑行测试长68%和103%（P < 0.001）。在非稳定骑行阶段，为克服自由骑行时增加的急动损失，产生了显著更多的额外曲柄功（伴随着向心功增加），相比固定档位骑行时更多。在固定档位骑行时，与健全受试者的骑行相比，肌肉做功的时间和关节位置在自由轮骑行时更相似，因为在前一种骑行模式的动力阶段，大部分功是由膝关节伸肌产生的。
在功能输出距离方面，强制平稳骑行优于自由骑行，这基于较少的能量消耗（较少的急动损失和肌肉张力）以及更高效的能量产生（更高效的做功时间和关节位置）。一些有利于固定档位骑行的能量机制主要在非稳定阶段起作用；其他机制在骑行的所有阶段持续起作用。
