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

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.

Cross-sectional analysis of 5652 women aged 45-70 years from the Korea National Health and Nutrition Examination Survey (2014-2023).

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.

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.

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.