To explore the effects of different sequential strength and endurance training on body composition and cardiorespiratory endurance of primary school students, and to provide theoretical basis for scientific guidance of primary school students’ fitness and improvement of children’s physical health. Subjects 60 boys in grade 5 of a primary school in Beijing (age: 10.22 y±0.73 y; height: 150.23 cm±9.63 cm; weight:45.71 kg±8.09 kg; BMI: 20.25 kg/m²±4.77 kg/m²).

The subjects were divided into three groups: simple endurance group (n=20), RE group (n=20) and ER group (n=20). Three groups of subjects were trained for 12 weeks, 3 times a week. Maximum oxygen uptake, body composition, lung function and other indicators were tested before and after intervention.One-way ANOVA and Paired Sample T-Test were used for statistical analysis.

After 12 weeks of exercise training intervention, there was no significant difference in the growth rate ofthe weight of the subjects between the three groups (Egroup: 2.78±7.23; REgroup: 4.00±7.20; ER groupin the same period: 3.47±7.94)(P>0.05).Compared with the simple endurance group, the percentage of physical fitness (Egroup: 10.69±3.34; RE group: 16.38±6.34; ER group: 23.15±10.30) was significantly decreased (P<0.01), and the ER group was better than the RE group (P<0.05). The muscle growth rate (Egroup: 6.84 ± 2.91; RE group: 12.58 ± 3.68; the ER group: 10.63±2.91) in the same period group was higher than the simple endurance group (P<0.01), and the RE group was higher than the ER group (P<0.05).The growth rate of vital capacity (Egroup: 12.71±4.64; RE group: 20.35±4.22; the ER group: 17.76±5.51) in the same period group was higher than that in the endurance group (P>0.05).There was no significant difference in the growth rate of vital capacity body mass index between the three groups (E group: 9.43±8.23; RE group: 16.55±7.96; the same period ER group: 13.44±10.26) (P>0.05).The maximum oxygen uptake growth rate (Egroup: 7.06±2.55; RE group: 14.10±4.12; the ER group: 11.26±4.04) in the same period group was higher than the endurance group (P>0.05).

Concurrent training is superior to simple endurance training in improving children’s body composition and cardiopulmonary endurance. The endurance-strength training sequence can effectively reduce the body fat content, the training sequence of strength-endurance can effectively increase the content of skeletal muscle and the improvement of children’s cardiopulmonary function is not related to the training sequence.