Background

Neuromuscular electrical stimulation (NMES) is an important therapeutic tool for rehabilitation. However, best stimulation parameters remain to be determined.

Objective

To determine the influence of different electrical stimulation currents and phase durations on torque, efficiency, and discomfort.

Methods

Using a cross-over design, kHz frequency alternating currents (KFAC) and pulsed currents (PC) with narrow (200 µs) or wide (500 µs) phase durations were randomly applied on knee extensor muscles of healthy participants with a minimum of seven days between sessions. The NMES-evoked torque, NMES-efficiency, and discomfort (visual 0−10 cm analogue scale) were measured for each stimulation intensity increments (10 mA). Statistics were conducted using a three-way analysis of variances (phase duration x current x intensity), followed by Tukey post-hoc.

Results

Twenty-four males (age 22.3 ± 3.5years) were included. No effect of NMES current was observed for torque, efficiency, and discomfort. For wide phase durations (500 µs), torque significantly increased for all stimulation intensities. For narrow phase durations (200 µs) evoked torque significantly increased only after 40% of maximal stimulation intensity. Phase durations of 500 µs produced greater torque than 200 µs. Discomfort was greater with 500 µs when compared to 200 µs. Submaximal relative torque, for example 40% of maximum voluntary contraction (MVC), was obtained with ∼ 60% and ∼ 80% of the maximal current intensity for 500 µs and 200 µs, respectively.

Conclusion

KFAC and PC current applied with the same phase duration induced similar relative submaximal and maximum evoked-torque, efficiency, and perceived discomfort. However, currents with 500 µs induced higher evoked-torque, current efficiency, and perceived discomfort.

中文翻译：

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不同电刺激电流和阶段持续时间对次最大和最大扭矩、效率和不适的影响：随机交叉试验

背景

神经肌肉电刺激（NMES）是康复的重要治疗工具。然而，最佳刺激参数仍有待确定。

客观的

确定不同电刺激电流和阶段持续时间对扭矩、效率和不适的影响。

方法

采用交叉设计，将具有窄相（200 µs）或宽相（500 µs）持续时间的 kHz 频率交流电 (KFAC) 和脉冲电流 (PC) 随机应用于健康参与者的膝伸肌，时间至少 7 天会话之间。针对每个刺激强度增量 (10 mA) 测量 NMES 诱发扭矩、NMES 效率和不适感（视觉 0−10 cm 模拟刻度）。使用三向方差分析（相持续时间 x 当前 x 强度）进行统计，然后采用 Tukey 事后分析。

结果

包括 24 名男性（年龄 22.3 ± 3.5 岁）。未观察到 NMES 电流对扭矩、效率和不适的影响。对于较宽的阶段持续时间（500 µs），所有刺激强度的扭矩均显着增加。对于窄相持续时间 (200 µs)，诱发扭矩仅在最大刺激强度的 40% 后显着增加。500 µs 的阶段持续时间产生的扭矩大于 200 µs。与 200 µs 相比，500 µs 的不适感更大。次最大相对扭矩，例如最大自主收缩 (MVC) 的 40%，分别在 500 µs 和 200 µs 内使用最大电流强度的 60% 和 80% 获得。

结论

以相同的相持续时间施加的 KFAC 和 PC 电流引起类似的相对次最大和最大诱发扭矩、效率和感知不适。然而，500 µs 的电流会引起更高的诱发扭矩、电流效率和感知不适。