Background: Academic procrastination (AP) has been a common problematic behavior in college students. While physical activity (PA) has been reported to increase self-efficacy and reduce AP, less is known about the potential relationships among them. Therefore, this study aimed to investigate the mediating effect of self-efficacy on the relationship between PA and AP. Methods: 687 Chinese college students (51% males, 49% females) aged 17–23 years (M = 19.59, SD = 0.89) participated in the study. PA, self-efficacy, and AP were assessed using the Physical Activity Rating Scale-3 (PARS-3), the Generalized Self-Efficacy Scale, and the Procrastination Assessment Scale-Students (PASS), respectively. Pearson correlation analysis, linear regression analysis, and mediation analysis were used to analyze the data. Results: (1) PA has a significant and negative impact on college students’ AP, (2) PA has a significant and positive impact on college students’ self-efficacy; (3) self-efficacy has a significant and negative impact on AP in college students; and (4) self-efficacy significantly mediates the relationship between PA and AP. Conclusions: PA is an effective intervention for directly and indirectly decreasing college students’ AP. Therefore, more intervention efforts should focus on the promotion of PA in higher education to improve students’ self-efficacy and thus, to reduce AP among college students.

Summary Osteoporosis is an increasing health problem in postmenopausal women. Our findings indicated that long-term brisk walking with a volume greater than 16 per week is effective for improving BMD in premenopausal women. Purpose To examine the effects of brisk walking on bone mineral density (BMD) in premenopausal women, and further determine the effective frequency, intensity, time and volume (frequency x duration) of brisk walking for training strategy prescription. Methods 222 healthy premenopausal women were recruited for BMD measurement. According to the survey of their physical activity level, 84 subjects (age: 46±1.8) whose physical activity index ≥40 were categorized into the brisk walking group, and 138 subjects (age: 47±2.2) whose physical activity index <40 were assigned to the sedentary group. The BMD of these two groups were statistically compared with an independent t test. Next, 35 subjects from the original sedentary group were recruited for BMD measurement after 2-year moderate brisk walking. According to the volume of physical activity per week, they were divided into the control group (n = 10, aged 49±0.9), volume 8 group (n = 4, aged 48±1.2), volume 12 group (n = 7, aged 49±1.4), volume 16 group (n = 8, aged 49±1.3), and volume 20 group (n = 6, aged 49±1.5). ANOVA was used to analyze BMD before and after brisk walking among the five groups. Results The BMD in the brisk walking group (1.00±0.008 g/cm2) was significantly higher than that in the sedentary group (0.89±0.008 g/cm2) (P<0.001). Stepwise regression analysis revealed that the volume of brisk walking was significantly correlated with BMD (P<0.001). In particular, brisk walking with a volume greater than 16 (a score of duration up to 4 and a score of frequency up to 4 or 5) per week is effective for improving BMD in premenopausal women (P = 0.03, P = 0.002, respectively). Conclusions Long-term brisk walking is an efficient way to improve BMD. Taking brisk walks for 30 minutes per day 3 or more times per week (volume>16) is recommended to prevent bone loss in premenopausal women.

The aim of this study was to investigate the applicability of the planned behavior theory model (TPB-5) and TPB-6 model of enhanced physical exercise in college students, and to explore the role of exercise commitment in the relationship between exercise intention and behavior, so as to provide theoretical and empirical support for college students to promotion exercise. The study participants were 581 college students (male = 243, female = 338, age = 19.27 ± 0.94) are investigated with Theory of Planned Behavior (TPB) Scale, Exercise Commitment Scale, and Physical Activity Rating Scale. Results showed that the explanatory power of the TPB to exercise intention and exercise behavior is 0.70 and 0.52, respectively, and exercise intention was the primary factor to predict exercise behavior of college students. The Model fit of TPB-6 model is acceptable, compared with TPB 5-factor model, the predictive power of TPB-6 (with the mediator: exercise commitment) on behavioral intention increases from 70.0 to 75.0%, and the predictive power towards behavior raises from 52.0 to 59.0%. Exercise commitment has a partial mediating effect between exercise intention and behavior, which accounts for 26.89% of the total effect, but it has no moderating effect. In conclusion, this research demonstrates the TPB-5 model has good applicability among the college students, with exercise commitment variables, exercise intention can better predict college students’ exercise behavior, which can be used as the theoretical basis for the intervention on their exercise behavior.