BackgroundSarcopenia is a common geriatric condition closely associated with cardiovascular diseases and other health issues. This study aims to investigate the causal relationship between sarcopenia-related traits and electrocardiogram(ECG) indices. MethodsWe conducted a comprehensive analysis utilizing summary data from genome-wide association studies (GWAS) associated with sarcopenia-related traits, including hand grip strength, lean body mass, and walking pace. ECG indices included PR interval, PP interval, ST duration, QRS duration and T wave duration. The primary analytical method employed was the inverse variance-weighted method (IVW). ResultsAccording to our study findings, we identified a significant association between sarcopenia-related traits and ECG indices. Specifically, we observed a positive correlation between increased muscle mass and certain ECG indices. For instance, increased limb muscle mass (including left arm, right arm, left leg, and right leg) was associated with prolonged PR interval and QRS duration. This suggests that enhancing muscle mass may impact the timing of cardiac electrical activity. Additionally, increased whole-body fat-free mass showed similar associations with cardiac electrical activity. ConclusionSarcopenia-related traits have a unidirectional causal relationship with ECG indices, indicating that sarcopenia affects cardiac electrical activity.