Sedentary behaviour, muscle diseases, fractures: Mendelian randomisation study.

Area of Science:

• Epidemiology
• Genetics
• Orthopedics

Background:

• Sedentary behaviors are increasingly prevalent globally.
• Understanding their impact on musculoskeletal health and fracture risk is crucial for public health.
• Previous observational studies have shown associations, but genetic evidence is limited.

Purpose of the Study:

• To investigate the causal associations between specific sedentary behaviors (driving, TV viewing, computer use) and the risk of musculoskeletal diseases and fractures.
• To utilize a Mendelian randomization approach to infer causality and mitigate confounding factors.

Main Methods:

• A two-sample Mendelian randomization (MR) analysis was performed using UK Biobank data.
• Genetic variants associated with sedentary behaviors and musculoskeletal outcomes served as instrumental variables.
• Inverse variance weighting, weighted median, and MR-Egger regression were employed for primary and complementary analyses.
• Sensitivity analyses included Cochran's Q test, MR-Egger intercept, and leave-one-out analysis.

Main Results:

• Television viewing showed a significant association with an increased risk of ankle fractures (P = 0.0182) and musculoskeletal diseases (P < 0.001).
• Computer use was inversely associated with musculoskeletal diseases (P = 0.0017), suggesting a potential protective effect.
• Heel bone mineral density was strongly associated with ankle fracture risk (P < 0.001).

Conclusions:

• Sedentary behaviors have heterogeneous effects on musculoskeletal health.
• Television viewing is linked to higher risks of ankle fractures and musculoskeletal diseases.
• Computer use may have a protective role, warranting further investigation into its mechanisms.