Abstract Body: Background: Adhering to guideline-recommended leisure-time physical activity (LTPA) is a key component for chronic disease prevention and recent studies suggest social relationships influence LTPA. However, the influence of social networks on activity patterns in Asian populations remains unclear.

Methods: This cross-sectional study included 125,457 adults aged 40-69 years from the Health Examinees study-G (HEXA-G) cohort. They were recruited from 38 health centers and hospitals in Korea from 2004 to 2013. The primary exposure was social network size by type (total, family, and non-family), each categorized into quartiles (Q1-Q4). Physical activity patterns, the primary outcome, were defined as inactive (<150 minutes moderate-to-vigorous physical activity (MVPA)/week), weekend warrior (≥150 minutes MVPA/week in ≤2 days), and regularly active (≥150 minutes MVPA/week in ≥3 days). Multinomial logistic regression analysis was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs), adjusting for age, BMI, waist circumference, education, income, marital status, smoking, alcohol intake, total caloric intake, chronic diseases and cancer diagnosis.

Results: Among participants (53±8 years of age; 66% women), 8.7% of men and 3.4% of women were weekend warriors, and 33.1% of men and 33.0% of women were regularly active. Regarding LTPA types, mountain climbing was most common among weekend warriors (41.2% in men and 39.7% in women), whereas aerobics/gym activities predominated among those regularly active (10.6% in men and 17.0% in women). Larger total networks were associated with greater physical activity. Associations were stronger for non-family networks, whereas family networks showed no consistent trends. Using inactive participants as reference, both men and women in Q4 of non-family networks had higher odds of being a weekend warrior than regularly active, compared to those in Q1: ORs (95% CIs) were 1.44 (1.29-1.61) and 1.22 (1.14-1.30) in men and 1.33 (1.18-1.50) and 1.25 (1.19-1.31) in women.

Conclusions: Larger social networks, particularly non-familial ties, were significantly associated with higher likelihood of being a weekend warrior or regularly active. Strengthening non-family social connections may be an effective approach to promote active lifestyles and reduce inactivity among middle-aged adults.