Legs cramps are a frequent disorder, which have a negative impact on quality of life, particularly among patients over 60 years old. Lifestyle factors such as alcohol consumption have been shown to be associated with nocturnal Leg cramps. this study aimed to explore the association between nocturnal leg cramps and a sedentary lifestyle among elderly patients. A case-control study was conducted with a Bayesian approach for sensitivity analysis. Patients over 60 years old consulting their family doctor were recruited in the Alsace region, france. cases were matched with controls free from cramps for age, sex, medical history and medications known to trigger cramps. the level of physical activity was assessed using the Dijon physical Activity Score (DpAS). We performed univariate and multivariate analyses adjusting for alcohol consumption. 272 participants were matched into 136 pairs. 11% of all were sedentary persons. Adjusting for alcohol consumption, we observed an association between nocturnal Leg cramps and a sedentary lifestyle oR = 9.84 (95% credibility interval [1.74; 101.9]; posterior probability 99.68%). Our findings represent an additional argument to promote physical activity to patients over 60 years old. They also highlight the need to develop and evaluate physical activity interventions in the treatment of nocturnal Legs cramps. Nocturnal Leg Cramps (NLC) are painful, involuntary contractions of muscles 1-3. NLC is a specific entity of idiopathic cramps occurring at rest in the lower limb during the night 4-7. NLC are associated with a reduced quality of sleep 6 and reduced physical component scores on the SF36 quality of life questionnaire 8. Among patients over 60 years old the cramp prevalence varies from 46% to 56% 4,9. Nonetheless, patients rarely report NLC to their general practitioners 4,10,11. One of the reasons may be the known lack of both effective and safe treatments 9,11-13. Specific medical conditions and drug treatments have been identified to be associated with muscle cramps 10,14. Recently, we also showed a strong association with the global consumption of alcoholic beverages 15. Still, most cramps are considered idiopathic 16 and their physiological mechanism remains unclear 10,14. Some authors suggest that neuromuscular structures located in muscle, tendons and nerve fibres seem to be involved in the trigger of muscle cramps 4-6. Congruently with this assumption, musculoskeletal conditions associated with sedentary lifestyle 17 as well as work postures 18-20 , prolonged standing 21 and western habit of sitting instead of squatting 22 have been suspected of causing cramps and specifically NLC. We hypothesize that there may be an association between sedentary lifestyle and NLC. To the best of our knowledge, no study confirmed such a link, our aim was therefore to assess the association between a sedentary lifestyle and Nocturnal Leg Cramps in elderly patients. Methods Study design. The study was conducted within 67 general practices of the Strasbourg General Medicine Department pract...