Combined associations of protein intake and resistance exercise with handgrip strength in postmenopausal women

Abstract

Objectives: To investigate the combined associations of dietary protein intake and resistance exercise with handgrip strength in Korean postmenopausal women, and whether these differ by time since menopause. Study design: Cross-sectional analysis of 5652 women aged 45-70 years from the Korea National Health and Nutrition Examination Survey (2014-2023). Main outcome measures: Participants were grouped by protein intake (<1.0 vs. >= 1.0 g/kg/day, and also <1.2 vs. >= 1.2 g/kg/day) and amount of resistance exercise regularly undertaken (<2 vs. >= 2 times/week). Analyses were stratified by menopausal duration (<= 10 vs. >10 years). Low handgrip strength (<18 kg) and mean handgrip strength were evaluated using survey weighted logistic and linear regression, adjusting for demographic, lifestyle, and clinical factors. Results: At the 1.0 g/kg/day threshold, the prevalence of low handgrip strength was 8.9 % in women with low protein and no exercise (G1) versus 4.2 % in those with adequate protein and exercise (G4, p = 0.004). In adjusted models, G4 showed a trend toward lower odds of low handgrip strength (odds ratio 0.57, 95 % confidence interval 0.31-1.05), while G3 (low protein + exercise) consistently showed higher mean handgrip strength. Findings were similar at the 1.2 g/kg/day threshold (overall p = 0.027). Associations were significant in women >10 years postmenopause, though the interaction by menopausal duration was not significant. Conclusions: Adequate protein intake (>= 1.0-1.2 g/kg/day) with regular resistance exercise (>= 2 times/week) was associated with stronger handgrip strength and lower odds of weakness. Resistance exercise appeared to be more strongly associated with handgrip strength than protein intake alone. Because of the cross-sectional design, these findings should be interpreted as observational associations rather than causal effects.