Objective This study aims to examine the distributional characteristics of weekly physical activity patterns ("insufficient" "concentrated" and "regular") and its relationship with physical fitness among children and adolescents.

Methods A total of 1,752 children and adolescents aged 6-18 years participated in this study. Moderate-to-vigorous physical activity (MVPA) was measured using accelerometers. Physical fitness was assessed according to the National Students' Physical Fitness Standards (Revised in 2014). Multivariate linear regression analysis was used to examine the relationship between the three physical activity patterns and the score of physical fitness, as well as the relationship between the average daily MVPA time and intensity and the score of physical fitness within each pattern.

Results ① Among the children and adolescents with an average MVPA of 60 minutes daily, the proportion of "regular" pattern was significantly higher than the proportion of "concentrated" pattern. (χ²=6.902, P=0.009), indicating that the "regular" was the predominant physical activity pattern. ② There were significant differences in the distribution of weekly physical activity patterns among children and adolescents of different genders (χ²=105.189, P<0.001), educational stages (χ²=268.665, P<0.001), and parental education levels (χ²=10.773, P=0.029). ③ The analysis of the total sample revealed that "concentrated" β=4.601, 95% CI (2.638, 6.564), P<0.001 and "regular" pattern β=6.390, 95% CI (4.489, 8.291), P<0.001 were both significantly related to increased total physical fitness score, there was no significant difference in the physical fitness score between the "concentrated" and "regular" pattern β=−0.513, 95% CI (−2.990, 1.964), P=0.685. The results of different educational stages were consistent with the total sample. ④ The analysis of the total sample indicated that an increase of average daily MVPA time was significantly related to an increase of the total physical fitness scores only in the "insufficient" pattern β=0.142, 95% CI (0.078, 0.205), P<0.001, while the intensity was not significantly related to the total physical fitness scores in any of the three patterns (P>0.05). The results of different educational stages were consistent with the total sample.

Conclusions Among the three patterns, the "concentrated" and "regular" pattern were more beneficial to the physical fitness of children and adolescents, and there was no significant difference in physical fitness between the two.