利用非对称高频载波脉冲簇电刺激的肌疲劳缓解技术研究

To alleviate muscle fatigue caused by neuromuscular electrical stimulation (NMES) and reduce the discomfort associated with high-frequency carrier pulse cluster electrical stimulation, this paper compares the anti-fatigue properties of the proposed asymmetric high-frequency carrier pulse cluster electrical stimulation with the conventional symmetric biphasic rectangular pulse electrical stimulation technique in healthy subjects. Specifically, the clustered narrow pulses with a carrier frequency of 10 kHz (high-frequency mode, HF) and the conventional symmetrical biphasic rectangular pulses (low-frequency mode, LF) are delivered to the proximal segment of the median/ulnar nerve bundles, eliciting the same level of contraction. Stimulation is continued for 5 minutes to induce muscle fatigue, and finger flexion forces and high-density electromyography (EMG) signals of the finger flexors are recorded. The results show that the rate of muscle fatigue is significantly reduced under the HF stimulation compared with the LF stimulation. This is manifested by a slower force decay rate, smaller absolute force decay (3. 868 8 + 1. 136 8) N, and a larger force plateau (7.296 + 1. 342 4) N, resulting in greater force output (2 282. 8 + 341. 48) N • s. The higher force-to-EMG amplitude ratio under the HF stimulation indicated a higher efficiency of muscle activation, which may be a potential mechanism for alleviating muscle fatigue by the HF modes. The present study suggests that the asymmetric pulse clusters at a kilohertz carrier frequency may significantly alleviate muscle fatigue by inducing a higher efficiency of muscle activation compared to the conventional symmetric LF stimulation, which can potentially promote the application of the NMES-based motor neurorehabilitation technique in stroke patients.