The motor unit is a fundamental building block of the motor nervous system. Comprising the anterior horn cell, its axonal projections and the associated muscle fibres, the motor unit is the central nervous system’s structural and physiological link with skeletal muscles. But are all motor units created equal? How is their firing controlled and what happens when this control is lost in amyotrophic lateral sclerosis (ALS)? With particular focus on fasciculations and motor unit decomposition, I will explore how we have been addressing these questions at King’s using high-density surface electromyography. This is a relatively new technique that is non-invasive and extremely well tolerated by patients for long periods of time. This is providing unprecedented precision during the quantification of motor unit activity, demonstrating excellent spatial and temporal resolution. A recent 14-month prospective study at King’s has indicated that fasciculation frequencies (number per minute) first rise in ALS patients while muscles remain strong, before rapidly declining in weak muscles. We hope that results like this can improve the utility and accessibility of outcome measures in clinical drug trials. I will also discuss ideas for the future, as we strive to introduce home-based monitoring.