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. Author manuscript; available in PMC: 2009 Jan 1.
Published in final edited form as: J Biomech. 2007 Aug 17;41(1):137–144. doi: 10.1016/j.jbiomech.2007.07.011

Fig. 3.

Fig. 3

Methods of verification. (a) Confirmation of proper muscle stimulation. The electrical stimulation pulse train consisted of four 300 μs pulses spaced at 30 ms intervals. The rectified EMG traces of four muscles were monitored over a 200 ms window following stimulus onset. The sharp peaks that occur in the EMG traces with each stimulating pulse correspond to stimulus artifact. The second peaks, seen only in the traces of stimulated muscles (RF and VM in the example above), reflect muscle activation. We compared the average value of the EMG traces in the time window between 13 and 26 ms following the first pulse (dashed lines) to assess whether or not the stimulus spilled over from stimulated to non-stimulated muscles. We also inspected each trace for possible reflex activity. (b) Confirmation of negligible spring-induced joint moments. Spring-induced joint moments and net joint moments were compared to determine the contribution that the springs made to the induced joint accelerations. In both (a) and (b), experimental worst-case results are shown.