Length dependent potentiation in electrically stimulated human ankle dorsiflexor muscles

P. Mela, Petrus H. Veltink, P.A.J.B.M. Huijing

    Research output: Contribution to journalArticleAcademicpeer-review


    Six able-bodied and three spinal cord injured (SCI) subjects took part in the study. Their isometric left dorsiflexor muscles were stimulated with two-second bursts at three ankle joint positions and movements at the ankle were measured. Trains with constant stimulation frequencies (CSF: 50, 25, 20, 16, 12, 8 Hz) and with decreasing stimulation frequencies (DSF1,2) were used. Each DSF tetanus consisted of four 0.5 second bursts of different frequencies (DSF1: 50, 25, 16, 8 Hz; DSF2: 50, 20, 12, 8 Hz). To evaluate the effect of preceding higher stimulation frequencies (DSF), the average moment at corresponding time intervals in the DSF and CSF trials were compared for 25, 20, 16, 12, 8 Hz. Preceding higher stimulation frequencies caused increase of the moment elicited by a given frequency. This was true for all the subjects at dorsiflexed positions, but the effect is highly dependent on joint ankle. At plantar flexed positions moment enhancement was seen only in SCI subjects. We conclude that effects of joint angle as well as individual muscle properties should be taken into account when optimizing muscle force by means of frequency modulation.
    Original languageUndefined
    Pages (from-to)120-130
    Number of pages11
    Issue number2
    Publication statusPublished - 2002


    • METIS-206021
    • muscle length
    • FES
    • Human muscle
    • Activation history
    • IR-61449

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