Relationship Between Handgrip Strength and Lung Function in Adults: The Role of Sex and Age.

Background The association between handgrip strength and lung function has been explored in previous studies, yet few studies have addressed how this relationship varies by sex and age in healthy populations. Additionally, few studies have investigated the utility of the lower limit of normal (LLN) for identifying abnormal lung function in relation to handgrip strength. This study aimed to evaluate sex- and age-specific associations between handgrip strength and lung function in a healthy adult population. Methods This cross-sectional study included individuals undergoing health check-ups at a regional hospital in Japan from April 2018 to March 2020. Data on demographics, anthropometrics, handgrip strength, spirometry, and lifestyle factors were collected. Handgrip strength was assessed using a digital dynamometer, with two measurements taken for each hand while keeping the arms straight down at the sides without touching the body. The highest recorded value from each hand was averaged as the final measure. Pearson's correlation and multiple regression analyses were conducted to explore the relationship between handgrip strength and lung function parameters. Logistic regression analyses were used to estimate odds ratios (OR) and 95% confidence intervals (CI) for abnormal lung function per 5 kg increase in handgrip strength. Results A total of 1622 individuals were included in the study. The correlation coefficients between handgrip strength and forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) were approximately 0.3-0.45 (p < 0.01) after stratification by sex. Linear regression analysis showed a positive association between handgrip strength and FEV1, percentage of the predicted FEV1 value (FEV1% predicted), FVC, and percentage of the predicted FVC value (FVC% predicted) across all age groups in women (p < 0.05). In men, these associations were significant in the 25-44 and 45-59 year age groups (p < 0.05). Logistic regression indicated that a 5 kg increase in handgrip strength was significantly associated with reduced abnormal lung function in both men (OR = 0.790, 95% CI = 0.673-0.927; p < 0.01) and women (OR = 0.598, 95% CI = 0.461-0.775; p < 0.01); however, the significance was nullified in men over 60 years of age after further age stratification. Conclusion Handgrip strength is positively associated with FEV1 and FVC, both in absolute and predicted percentage values, across all age groups in women and in men under 60 years of age. A 5 kg increase in handgrip strength is significantly associated with lower abnormal lung function in women. Handgrip strength measurements integrated into regular health checkups may help in the early detection of lung function abnormalities, even in early adulthood. Further longitudinal studies are warranted to validate these findings.