Impaired post-tetanic potentiation of muscle twitch in myasthenia gravis.

•A novel method using an accelerometer was used to evaluate post-tetanic potentiation of muscle twitch in myasthenia gravis.•Significant decrease in post-tetanic potentiation of muscle twitch may be associated with impairment of excitation–contraction coupling in myasthenia gravis.•The present method has high sensitivity in detecting impairment of excitation–contraction coupling in myasthenia gravis.