This This study aimed to investigate the impact of muscle-related physical function indicators on phase angle (PhA) and to identify their relationships using multiple regression analysis. We used raw data from the 9th Korea National Health and Nutrition Examination Survey (KNHANES) conducted in 2022. Among the respondents, 4,820 adults aged 20 years and older were initially included, but 612 individuals who did not undergo body composition measurements and 446 who reported using the left hand, both hands, or provided no response, were excluded. Thus, 3,762 participants were analyzed.
The results showed that the whole-body phase angle had a very low correlation with total physical activity (r = .091), days of resistance exercise per week (r = .164), days of practicing physical activity for more than 60 minutes per day (r = .181), and body fat (r = .045). There was a low correlation between the whole-body phase angle and waist circumference (r = .273), as well as body fat percentage (r = -.325). Conversely, the whole-body phase angle showed a stronger correlation with right handgrip strength (r = .584), left handgrip strength (r = .596), height (r = .464), weight (r = .496), and neck circumference (r = .487). Notably, the total fat-free mass showed a high correlation with the whole-body phase angle (r = .633), and all variables were statistically significant at the .01 level. The stepwise multiple regression analysis revealed that total fat-free mass, left handgrip strength, height, waist circumference, right handgrip strength, and body fat percentage, in that order, influenced the phase angle. Therefore, PhA positively correlates with fat-free mass and handgrip strength. Considering that PhA measurement can assess muscle mass and function, it may serve as a simple and efficient method for comprehensive monitoring of muscle mass and quality.