Background: The objective of this study was to investigate the effect of backpack carriage in different weights on ground reaction force components, loading rate and free moment of schoolchildren’s gait. Methods: Twenty-one healthy primary school children (8–11 years old) of second, third, fourth and fifth grade participated in this study where quasi-experimental design was administered. The weight of the backpacks used was 7.5, 10, 12.5 and 15 percent of the participant’s body weight. Gait was evaluated using a Kistler force plate at a frequency of 1000 Hz. The GRF along anterior-posterior(y), and medial-lateral (x) and vertical (z) axes, time to peak (TTP), the rate of loading, free moment were calculated. A repeated-measures ANOVA was used to compare the data between subjects. Results: The amplitudes of Fy2 and Fx2 were affected by the carrying load with 15 percent body weight. The amplitudes of Fy1, Fz1 and Fz3 were also affected by the carrying load with 12 and 15 percent body weight. Conclusions: The carrying load with %12 and 15% of the body weight altered schoolchildren’s gait performance. These altered variables should be considered as a risk factor for carrying a backpack.
