BACKGROUND: Quarantine was the measure taken by governments to control the rapid spread of COVID-19. This restriction resulted in a sudden change in people's lifestyle, leading to an increase in sedentary behavior and a related decrease in the practice of physical activity (PA). However, in neuromuscular diseases patients need to perform regular PA to counteract the negative consequences of the disease. Hence, the aim of this study was to estimate the levels of PA, measured as energy expenditure (MET-minute/week), among patients with neuromuscular disease (NMD) before and during the last week of quarantine. METHODS: A total of 268 Italian subjects, living in Sicily, completed an adapted version of the IPAQ-SF. Participants comprised 149 NMD, enrolled at the Neuromuscular Clinic of Palermo and 119 healthy subjects (control group). The SF-12 questionnaire was also administered to NMD. The Mann-Whitney U and the Kruskal-Wallis rank-sum tests were used for statistical analyses. RESULTS: We observed a significant decrease of the total weekly PA level during COVID-19 quarantine in both patients and controls. Moreover, a significant difference in the total weekly PA level was found depending on the presence of neuromuscular disease, impaired walking, gender and BMI. Finally, we found a correlation between SF-12 scores and the entity of the reduction of PA level during quarantine, thus confirming a relevant association with the quality of life in NMD. CONCLUSION: Our study confirmed that COVID-19 quarantine has affected the practice of PA among both NMD and healthy controls.