Handgrip Strength-Related Factors Affecting Health Outcomes in Young Adults: Association with Cardiorespiratory Fitness

Abstract

Objectives. Handgrip strength (HS) is a risk factor of all-cause mortality and cardiovascular diseases. However, the influencing factors and mechanisms contributing to this correlation remain unclear. Therefore, we aimed to explore factors related to HS and investigated the mechanism underlying its risk predictive value. Methods. This was a prospective, cross-sectional study. One hundred forty-five participants were recruited from December 2019 to November 2020. HS was measured using a hydraulic hand dynamometer and adjusted for body mass index (HSBMI) and body surface area (HSBSA). Body composition was assessed via bioimpedance spectroscopy. Physical fitness was measured using a cardiopulmonary exercise test system. Univariate, multiple linear regression analyses and receiver operator characteristic curve (ROC) were conducted to evaluate the associations between various participant characteristics and HS. Results. The average participant age was $21.68\pm 2.61\text{years}$ (42.8% were male). We found positive correlations between HSBMI/HSBSA and VO2max, VEmax, Loadmax, and METmax in both sexes ( $p<0.05$ ). Lean-tissue, protein, total water, and inorganic salt percentages were positively correlated, and fat percentage was negatively correlated with HSBMI in men and with HSBMI and HSBSA in women ( $p<0.05$ ). Multiple regression revealed that VO2max was independently associated with HSBSA in both sexes ( $\beta =0.215$ , 0.173; $95\%\text{confidence}\text{interval}\left[\text{CI}\right]=0.032-0.398$ , 0.026-0.321; $p=0.022$ , 0.022, respectively) and independently associated with HSBMI in women ( $\beta =0.016$ , $95\%\text{CI}=0.004-0.029$ , $p=0.011$ ). ROC analysis showed that HSBMI and HSBSA can moderately identify normal VO2max in men ( $\text{area}\text{under}\text{curve}\left[\text{AUC}\right]=0.754$ , 0.769; $p=0.002$ , 0.001, respectively) and marginally identify normal VO2max in women ( $\text{AUC}=0.643$ , 0.635; $p=0.029$ , 0.042, respectively). Conclusions. BMI- and BSA-adjusted HS could serve as indicators of physical health, and HSBSA may moderately reflect cardiorespiratory fitness levels in healthy young adults, particularly in males. Clinical trials registry site and number: China Clinical Trial Center (ChiCTR1900028228).