Association between adherence to healthy lifestyle factors and handgrip strength among Korean older adults

Lifestyle factors have been associated with muscle strength. However, little is known about the association of adherence to multiple healthy lifestyle factors with muscle strength in non-Western populations. We conducted a cross-sectional analysis of 4,253 Korean older adults (aged ≥ 65 years) using data from the Korea National Health and Nutrition Examination Survey 2014–2019. A healthy lifestyle score was created by summing six self-reported healthy lifestyle factors: non-smoking, no alcohol consumption or drinking 2–4 times/month or less, sleeping 6–8 h/day, ≥ ​150 min/week moderate-intensity or ≥ 75 min/week vigorous-intensity aerobic physical activity, ≥ 2 d/week muscle-strengthening exercise, and protein intake of ≥ 0.8 g/kg of body weight/d. Participants were categorized into four groups according to their healthy lifestyle score (0–2, 3, 4, and 5–6), using the 0–2 group as the reference. Handgrip strength (HGS) was assessed using a digital hand dynamometer. According to the Asian Working Group for Sarcopenia (AWGS) 2019 criteria, HGS ≥ 28 kg in men and ≥ 18 kg in women was classified as “above the cutoff for low HGS” Multivariable logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for having HGS above the cutoff according to the healthy lifestyle score, adjusting for potential confounders. Higher healthy lifestyle scores (5–6 vs. 0–2) were associated with higher odds of HGS above the AWGS 2019 cutoff (OR [95% CI] = 2.18 [1.61, 2.96]; P-trend < 0.001). The positive association was more pronounced among men (2.81 [1.82–4.36]; P-trend < 0.001) than among women (1.66 [1.06–2.60]; P-trend = 0.008), with statistically significant interaction by sex (P-interaction = 0.03). Positive associations were generally observed across subgroups defined by age, education, income, residential area, and marital status. No statistically significant interactions were observed between healthy lifestyle score and any of these sociodemographic characteristics. Our findings support the potential benefits of greater adherence to multiple healthy lifestyle behaviors for maintaining muscle strength among Korean older adults.