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EURASIP Journal on Advances in Signal Processing
Figure 1 | EURASIP Journal on Advances in Signal Processing

Figure 1

From: Nonlinear analysis of electromyogram following gait training with myoelectrically triggered neuromuscular electrical stimulation in stroke survivors

Figure 1

Top panel: Experimental setup for EMG-triggered NMES training. The signal flow is overlaid where the raw surface EMG was collected from MG muscle, which was amplified and low-pass filtered (anti-aliasing, frequency cutoff = 1000 Hz) before being sampled at 2400 Hz by 16-bit data acquisition system (NI USB-6215, National Instruments, USA) in a personal computer (PC). The LE was computed after digitally band-pass filtering (5th order Butterworth, 3 dB bandwidth = 10–500 Hz), then full-wave rectification and the low-pass filtering (5th order Butterworth, 3 dB frequency cutoff = 3 Hz) the sampled EMG signal. Visual biofeedback of the control signal (150 ms sliding window) was provided to the subject on a computer monitor (bottom panel) while the subjects learned to trigger the stimulation by activating their paretic MG muscle by exceeding a subject-specific threshold of 75% of their maximal voluntary contraction (MVC) in conjunction with heel-rise detected by the heel-switch of the ODFS Pace (Odstock, UK) electrical stimulator. Bottom panel: EMG visual biofeedback for EMG-triggered NMES training.

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