Abstract

Background: Pinch strength is required for activities of daily living, and any decline in it can cause difficulty with fine motor skills, such as fastening buttons or tying shoelaces. Thus, it is important to prevent the deterioration of pinch strength. Muscle strength is positively related to muscle mass. Conversely, it has been reported that changes in muscle mass and muscle strength do not always correspond and bioelectrical impedance analysis is a relatively easy method to measure muscle mass. But there has been little study of how upper extremity muscle mass using bioelectrical impedance analysis influences pinch strength. In this study, we aimed to investigate the relationship between upper extremity muscle mass and pinch strength. Furthermore, we examined the association between upper extremity fat mass and pinch strength.
Methods: This cross-sectional study included 82 healthy young men and women aged 20-22 years (mean age, 21.1 ± 0.7 years). Maximum lateral pinch strength was measured using a digital pinch sensor. Upper extremity muscle mass and fat mass were estimated using bioelectrical impedance analysis. The relationships between pinch strength, upper extremity muscle mass, and upper extremity fat mass were assessed using correlation and multiple regression analyses.
Results: Men had a greater pinch strength and upper extremity muscle mass than women (P < 0.05); however, there was no significant difference in upper extremity fat mass (P > 0.05). Pinch strength showed a significantly positive association with upper extremity muscle mass (P < 0.05), but not with upper extremity fat mass (P > 0.05). In multiple regression analysis adjusted for sex, upper extremity muscle mass was found to be a significant explanatory variable for pinch strength (P < 0.05).
Conclusion: To prevent the decline in pinch strength, preserving the ability of daily living activities that involve the hands, such as fastening buttons or tying shoelaces, needs to be focused on by improving upper extremity muscle mass using bioelectrical impedance analysis.