The Effect of Fatigue Due to Backpack Carriage with Different Weights on Shear and Vertical Components of Walking Ground Reaction Forces in Healthy Students

Introduction: The risk factors of fatigue while carrying bags with different weights in students are unknown. Therefore, this study aimed to investigate the effect of fatigue due to carrying backpacks with different weights on the kinetic parameters of gait in students.Methods: This study was quasi-experimental research. The statistical population of this study consisted of healthy male students. To investigate the effects of fatigue due to backpack carriage, backpacks with7.5, 10, 12.5%​​, and 15% body weight were used before and after fatigue. The fatigue protocol consisted of 10-minute walking and carrying a backpack with 10 percent of body weight. Kistler force plates were used to measure the ground reaction forces. For statistical analysis, paired sample t-test was used through SPSS v. 20.Results: Fatigue in the healthy group increased propulsive force (10 and 12.5% BW), braking force, vertical force of the first peak of Fz1, whereas it decreased Fz2 valley force (with 7.5 and 10 BW) (P≤0/05). The carrying load increased the second peak of Fz3 in most levels after fatigue (P≤0/05). In addition, the carrying load increased the valley (Fz2) by a 15% level compared to other levels after fatigue (P≤0.05).Conclusion: Muscle fatigue caused by carrying a backpack changes the reaction forces of the ground, so it is considered an important risk factor for secondary effects such as abnormalities or injuries in the lower extremities. Therefore, students, parents, and primary school teachers are advised to pay special attention to the weight of the backpack