The effect of backpack carriage in different weights and gradients on ground reaction force parameters of ۱۰-۱۲ year old schoolboys walking on instrumented treadmill

Schoolchildren have to carry their backpacks every day on routes with different conditions and slopes. However, the knowledge available on its effects on walking biomechanics is very limited. Therefore, this study aims to evaluate the effects of backpack carriage with ۱۰ and ۱۵ percent weights (which is recommended by researches as optimal weight for children on even surface) and ±۱۵ percent gradients on the kinetics of schoolboys’ gait.۱۸ primary schoolchildren living in Tehran city, Iran, with age range of ۱۰ ۱۲ years completed ۷ randomized trials of walking on an instrumented treadmill (belt-driven instrumented HP Cosmos Gaitway treadmill with Kistler forceplates): Three tasks on flat surface, including without backpack and with backpacks with ۱۰% and ۱۵% of body weight load as the control groups, two tasks on a ۱۵% positive gradient, and two tasks on a ۱۵% negative gradient. The Value of the vertical ground reaction force parameters including the first force peak, second force peak, mid-support force, loading rate, push-off rate, and time-to-peak (TTP) was extracted.The results of repeated measure ANOVA test showed that the effect of gradient on the first and second peaks, mid-support force, loading rate, rate of push-off, and TTP of gait was significant in both weights (p≤۰.۰۰۱). But the effect of backpack weights on the kinetics was not significant.First peak and TTP value increased significantly in downhill. Second force peak, loading rate, push-off rate (just in downhill), and mid-support force (in both downhill and uphill) decreased significantly. Carrying backpacks downhill will have more impacts on the children’s motor system, so that it seemed to have a different motor control strategy. The modification of backpack carriage methods can be one of the leading strategies to reduce the negative effects of stress on the musculoskeletal system of children. Determining the optimal appropriate weight of backpack is still a challenge because the students travel routes are not straight and even, but they have different slopes.

کلیدواژه ها:

Backpack ، Gait ، Gradient ، Kinetics ، Schoolchildren