Dose-response Relationship between Bouts of Physical Activity and Physical Health in Preschool Children

Objective: To examine the dose-response relationship between bouts of physical activity and physical fitness in preschool children. Methods: Sporadic sessions(2~4 s) of moderate-to-vigorous physical activity(MVPA), short bouts(5~9 s) of MVPA;and medium-to-long bouts(≥10 s) of MVPA were measured over 7 days by using accelerometers. Healthy fitness tests including cardiorespiratory endurance, muscle strength and speed/agility. The bouts of physical activity and composite scores were categorized into quartiles(Q1~Q4 group) by sex, the highest quartile(Q4) denotes as high healthy fitness(HPH). Logistic and linear regression were used to analyze the relationship between bouts of MVPA and HPH. Results: A total of 265 participants were included in statistical analysis(149 boys, 116 girls, 57.19 ± 5.33 months old). After adjustment for confounding factors and compared to Q1 group, the odds ratio for HPH in Q4 were 11.72(95% CI: 2.27, 60.53)、7.53(95% CI: 1.83, 30.90) and 8.98(95% CI: 1.78, 45.39)for sporadic MVPA, short bouts and medium-to-long bouts of MVPA in boys, respectively. Similar results were observed in girls as well, and the results were 11.85(95% CI: 2.33, 60.19)、12.34(95% CI: 2.47, 61.57) and 8.58(95% CI: 1.70, 43.41), respectively. In addition, there was a non-linear relationship between overall MVPA and HPH in boys. If the total MVPA ≤ 65 minutes/day, the OR of achieving HPH increased by 19%(OR=1.19, 95% CI: 1.03, 1.37) for every 1 minute/day increment in total MVPA; but if the total MVPA > 65 minutes/day, the OR of achieving HPH was not go up further. However, the non-linear relationship was not found in girls. Conclusion: There is a significant dose-response relationship between bouts of MVPA and HPH in preschool children.In boys, the OR of achieving HPH was progressively increased if the total MVPA ≤ 65 minutes/day.