Effect of Personality and Physical Activity on Bone Mineral Density in College Students: A Cross-sectional Survey

Objective To explore the correlation between 5 dimensions of personality, physical activity (PA), and bone mineral density (BMD) among college students.

Methods A total of 705 undergraduates (329 males and 376 females) from a sports university were recruited. Based on their sports training experience, the participants were divided into 6 major sports groups, including ball sports, skilled sports, competitive sports, track and field, leisure sports, and no sports. Students with professional sports training (ie, athletes) were categorized into ballgame, skilled, competitive, and track and field groups, while the rest (non-athletes) were placed in leisure and no sports groups. Ten-Item Personality Inventory in China (TIPI-C), or the 5-factor model of personality, was used to measure the 5 personality dimensions of openness, conscientiousness, extraversion, agreeableness, and neuroticism of the participants. Their daily level was measured with GT3X+ triaxial accelerometers over 7 continuous days. Then, parameter thresholds were established and the participants' PA was categorized as light (LPA), moderate (MPA), and vigorous (VPA). The bone mineral density (BMD) of arms, legs, and the total body was measured using dual-energy X-ray absorptiometry. The mediation effect of PA and that of the 5-factor model of personality were tested using PROCESS and Sobel tests. The correlation between the 5 personality dimensions, PA, and BMD was explored, with PA and the 5 personality dimensions as mediator variables. A comparison of PA and BMD was conducted across the 6 major sports groups. The correlation between PA of different intensities and BMD was also analyzed using Spearman's correlation.

Results Although there were 90 potential relationships between PA, the 5 personality dimensions, and BMD, only 3 were significant. When conscientiousness was used as an independent variable and MPA, as a mediating variable, statistically significant differences in PROCESS results were reported (P<0.01), with MPA mediating 17.3% of arm BMD, 19.4% of leg BMD, and 19.1% of total body BMD. Among male students, there was no significant difference in LPA among the 6 groups, but significant differences in MPA and VPA (P<0.05). Among female students, significant differences in LPA, MPA, and VPA were observed in all 6 groups and the differences between MPA and VPA were especially prominent (P<0.05). For both males and females, the differences in arm, leg, and total body BMD across the 6 groups were statistically significant (P<0.05), with these differences being more pronounced in females. There was no correlation between LPA and BMD in either sex. MPA and VPA were positively correlated with BMD, with MPA correlating with arm, leg, and total body BMD (males, Spearman's correlation r_s: 0.11-0.14, P<0.05; females, r_s: 0.20-0.23, P<0.01). VPA correlated with arm, leg, and total body BMD (males, r_s: 0.11-0.23, P<0.05; females, r_s: 0.26-0.30, P<0.01).

Conclusion MPA is associated with BMD in college students scoring high in the conscientiousness dimension of personality. In addition, there is a weak positive correlation between both MPA and VPA and BMD levels, with these associations being more pronounced in females.