Electromyography (EMG) may show normal or myopathic results (short duration, polyphasic, small amplitude MUAPs). Before exercise, a minority of GSD-V patients show myopathic results (5/25 patients); whereas after 5 minutes of high-intensity isometric exercise, the majority showed myopathic results (22/25 patients). The myopathic results were a decrease in CMAP amplitude, which was evident immediately after exercise and, after a plateau phase of a few minutes, reached its maximum after 30 minutes.
Electromyography (EMG) may show normal or myopathic results (short duration, polyphasic small amplitude MUAPs). Before exercise, a minority of GSD-V patients show myopathic results (5/25 patients); whereas after 5 minutes of high-intensity isometric exercise, the majority showed myopathic results (22/25 patients). The myopathic results were a decrease in CMAP amplitude, which was evident immediately after exercise and after a plateau phase of a few minutes reached its maximum after 30 minutes.