Cardiovascular Research Laboratory, Spaulding Hospital Cambridge, Cambridge, MA.
Department of Physical Medicine & Rehabilitation, Harvard Medical School, Cambridge, MA.
PM R. 2020 Jul;12(7):699-705. doi: 10.1002/pmrj.12282. Epub 2019 Dec 12.
Functional electrical stimulation (FES) is widely used to induce functional movements for paralyzed muscles. However, rapid muscle fatigue during FES-induced muscle contractions limits FES clinical efficacy.
To investigate muscle fatigue response across stimulation patterns and frequencies during FES in able-bodied individuals and in those with spinal cord injury (SCI).
Four stimulation protocols combining 20 and 40 Hz average frequency with either constant frequency trains (CFTs) or with doublet frequency trains (DFTs) were applied to the quadriceps of seven adults with SCI and eight able-bodied participants.
A FES-row training laboratory.
Seven individuals with SCI (one female; age range, 25 ± 6 years) and eight age-matched able-bodied participants (one female).
None.
Fatigue was defined as the number of contractions until force decreased by 20% from the target level of 25% maximal contraction force. The number of contractions and the stimulation current used during the four stimulation protocols were compared.
There was a significant effect of frequency, as well as interaction between group and stimulation pattern (P < .05). In both groups, 20-Hz trains increased the number of contractions to fatigue compared to 40-Hz trains. However, the responses to the pattern of stimulation differed. In the able-bodied participants, CFT increased the number of contractions to fatigue compared to DFT, whereas in those with SCI, DFT increased the number of contractions to fatigue. In fact, DFT resulted in similar number of contractions to fatigue in both populations.
These results indicate that DFT at 20 Hz may be a better stimulation protocol to delay fatigue onset in the SCI population than the other three protocols. In addition, this work implies that results from able-bodied persons may not be directly applicable to those with SCI.
功能性电刺激（FES）被广泛用于诱导瘫痪肌肉的功能性运动。然而，在 FES 诱导的肌肉收缩过程中，肌肉疲劳迅速发生，限制了 FES 的临床疗效。
研究健康个体和脊髓损伤（SCI）个体在 FES 中，不同刺激模式和频率下的肌肉疲劳反应。
将 20 和 40 Hz 两种平均频率与恒定频率（CFT）或双脉冲频率（DFT）相结合的 4 种刺激方案应用于 7 名 SCI 成人和 8 名健康对照者的股四头肌。
FES 训练实验室。
7 名 SCI 患者（女性 1 例；年龄范围 25 ± 6 岁）和 8 名年龄匹配的健康对照者（女性 1 例）。
无。
疲劳定义为力下降至目标水平的 25%最大收缩力的 20%时的收缩次数。比较了 4 种刺激方案中的收缩次数和刺激电流。
频率有显著影响，组间和刺激模式间也存在交互作用（P < 0.05）。在两组中，20 Hz 的刺激比 40 Hz 的刺激产生更多的收缩次数至疲劳。然而，对刺激模式的反应不同。在健康对照组中，CFT 比 DFT 增加了收缩次数至疲劳，而在 SCI 患者中，DFT 增加了收缩次数至疲劳。事实上，DFT 使两种人群达到疲劳的收缩次数相似。
这些结果表明，20 Hz 的 DFT 可能是一种比其他三种方案更好的刺激方案，可延迟 SCI 人群的疲劳发生。此外，这项工作表明，健康人群的结果可能不能直接应用于 SCI 患者。
