To investigate the causal association between sarcopenia and hypertension and the mediating role of sedentary behavior using Mendelian randomization.

The summary statistical data of sarcopenia-related indicators,sedentary behavior (television watching,computer use and driving) and hypertension were extracted from IEU Open GWAS database website.Univariate Mendelian randomization was used to explore the association between the indicators of sarcopenia and hypertension, and two-step Mendelian randomization was used to investigate whether sedentary behaviors (television watching, computer use and driving) mediated the causal association.

Univariate Mendelian randomization revealed that all four indicators of sarcopenia were negatively associated with hypertension, including appendicular lean mass (OR=0.92, 95% CI: 0.88-0.96), left grip strength (OR=0.78, 95% CI: 0.66-0.92), right grip strength (OR=0.78, 95% CI: 0.66-0.91) and walking pace (OR=0.20, 95% CI: 0.14-0.30). Furthermore, two-step Mendelian randomization showed that television watching partially mediated the causal association between left grip strength (22.92%) and right grip strength (23.62%) and hypertension, respectively.

All four indicators of sarcopenia had negative causal associations with hypertension and that television watching mediated part of the causal association between left and right grip strength and hypertension.