Internal and External Load Variations in Young Students: Comparisons between Small-Sided Games and Small-Sided Games Combined with Strength Training during Physical Education Classes

The purpose of this study was to compare the effects of internal and external load in soccer small-sided games (SSGs) and a strength program based on CrossFit combined with SSGs for 7 weeks. Fifty-five students participated in this research (age: 9.04 +/- 0.19 years) and were randomly assigned to SSGs (n = 27) or strength combined with SSGs (n = 29) group. Two sessions/week were implemented. The results revealed that internal load on SSGs promoted higher levels (p <= 0.001; d = 0.35) of light physical activity (PA) (12.24 cpm) compared with strength combined with SSGs (11.46) and % heart rate (%HR) max (p = 0.002; d = 0.48) between SSGs (96.21) regarding strength combined with SSGs (92.09). On external load, significant differences appear in total distance (p <= 0.001; d = 0.80) on SSGs (1326 m) compared with strength combined with SSGs (1004 m) and mean velocity (p <= 0.001; d = 0.63) in both groups; 2.71 km/h on SSGs and 2.26 km/h on strength combined with SSGs. The SSGs seem to be more appropriate at the beginning of sessions, but as the weeks advance, strength combined with SSGs results in improved internal load compared with SSGs.