Pathological spontaneous activity of muscles is a clinically relevant feature of many neuromuscular diseases and, with a few exceptions, can only be detected using invasive measurements of the electrical muscle activity, which is conventionally performed using needle electrodes. It is still unclear why non-invasive surface electrodes cannot detect most forms of pathological spontaneous activity. Recent developments of novel electrodes have enabled high-resolution characterization of a muscle’s electric activity. In addition, we can use multiscale models to directly link the cellular behaviour of muscle fibres and the measured signals. The combination of measurements and computer simulations thus allows us to answer this fundamental question and improve our understanding of neuromuscular diseases.