Purpose: To examine the effects of three types of school-based exercises on bone health and physical fitness function in Chinese boys and girls. Methods: One hundred and seventy-four Chinese boys and girls were randomly assigned into four groups: (1) sham exercise (ShEx); (2) high-impact exercise (HiEx); (3) high-impact exercise with various directions (HiExVi); and (4) high-intensity interval exercise (HiInEx). Speed of sound (SOS) and physical fitness parameters were determined before and after six-month intervention. Results: At the end of six-month intervention, participants in all groups show an increment of SOS compared with the baseline (p < 0.05), and the changes were higher in HiEx (mean: 38.878 m/s, 95% CI: 32.885~44.872, p = 0.001) and HiExVi groups (49.317 m/s, 42.737~55.897, p < 0.001) compared with ShEx group (20.049 m/s, 13.751~26.346). Six-month exercise training generated a reduction of percent of body fat (PBF) and waist–hip ratio (WHR) (p < 0.05). The decrease of PBF was greater in HiExVi (−1.222%, −1.820~−0.624, p = 0.012) and HiInEx groups (−1.395%, −1.809~−0.982, p = 0.003), whereas the reduction of WHR was larger in HiEx (−0.026, −0.039~−0.014, p = 0.009), HiExVi (−0.024, −0.036~−0.012, p = 0.021), and HiInEx groups (−0.035, −0.046~−0.024, p < 0.001) compared with ShEx group. Balance function (BLF), vital capacity (VC), standing long jump (SLJ), and sit up (SU) increased in all intervention groups (p < 0.05). The BLF increased in HiEx (6.332 s, 4.136~8.528, p = 0.001), HiExVi (10.489 s, 8.934~12.045, p < 0.001), and HiInEx groups (9.103 s, 7.430~10.776, p < 0.001) showed a greater change than that of ShEx group (1.727 s, 0.684 ~2.770). The increment of VC (273.049 mL, 199.510~346.587, p < 0.001) and SU (2.537 times/min, 0.639~4.435, p = 0.017) was higher in HiInEx group, whereas the accrual in SLJ was larger in HiExVi (7.488 cm, 4.936~10.040, p = 0.007) compared with ShEx group (58.902 mL, 7.990 ~109.814; −0.463 times/min, −2.003~1.077; 1.488 cm, −0.654 ~3.630). Conclusion: The brief school-based exercises were effective in improving schoolchildren’s health, but they showed different effects, with HiEx mostly improving bone health, HiInEx largely benefiting physical fitness function, and HiExVi enhancing both bone and physical fitness.

BackgroundMental health has become a major public health issue worldwide. Biological and epidemiological studies have suggested that diet and physical fitness play a role in the prevention or cure of mental disorders. However, further research is required to elucidate the relationship between diet, physical fitness, and mental health. The study aims to provide a theoretical basis for promoting an adolescent healthy lifestyle and preventing mental problems by exploring the relationship between physical fitness, calcium intake, calorie intake, and adolescent mental health.MethodsA cross-sectional study of a sample of adolescents (N = 253, 12–13 years) was conducted. The study involved adolescents from three middle schools in Central Jiangsu Province, including 136 boys and 117 girls. Weight, height, and body mass index were measured. Physical fitness was scored using the Chinese National Student Physical Fitness Standard. Diet data were collected using a weighed 7-day food diary to estimate energy intake and dietary calcium intake. The mental health status of the participants was assessed using the Chinese Middle School Student Mental Health Scale. A T-test and analysis of variance were used to analyze the differences of variables between different genders and body mass index, and Pearson correlation and stepwise multiple regression were used to explore the relationship between physical fitness, dietary intake, and mental health.ResultsThe height (165.13 ± 8.07), weight (55.24 ± 13.00), and strength quality (64.93 ± 21.66) of boys are higher than those of girls (161.67 ± 6.44,48.99 ± 8.97, 58.40 ± 23.75, P &lt; 0.05), and the flexibility quality (74.59 ± 14.75) of girls is higher than that of boys (68.30 ± 20.84) (P &lt; 0.05). There were significant differences in the total scores of speed and physical fitness (F values were 4.02187.73, 3.07, 5.95, 10.33, and 9.52, respectively, P &lt; 0.05). There was a significant positive correlation between calcium intake, cardiopulmonary fitness, and mental health (r = 0.276, P &lt; 0.01; r = 0.159, P &lt; 0.05). Calcium intake and cardiopulmonary fitness could explain 8.4% of the changes in the mental health of adolescents aged 12–13(ΔR2 = 0.084, P &lt; 0.05).ConclusionAdequate calcium intake and the improvement of cardiopulmonary fitness in adolescents aged 12–13 are essential for the good development of their mental health. Future research in this field should examine the prospective associations between multiple measures of physical fitness composition and other nutrients ingested and mental health outcomes, as well as intervention studies that seek to provide evidence of causality.