Effects of Backpacks on Ground Reaction Forces in Children of Different Ages When Walking, Running, and Jumping

Abstract

Backpacks for transporting school loads are heavily utilized by children, and their mechanical advantages have been allowing children to transport heavy loads. These heavy loads may increase ground reaction forces (GRFs), which can have a negative effect on joints and bone health. The aim of this study was to investigate the effect of backpacks on the GRFs generated by children during walking, running, and jumping. Twenty-one children from the fifth (G-5, n = 9) and ninth (G-9, n = 12) grades walked, ran, and jumped over a force plate. When walking, the G-5 had GRF increments in the first (17.3%; p < 0.001) and second (15.4%; p < 0.001) peak magnitude, and in the total integral of the vertical force (20%; p < 0.001), compared to the control condition (i.e., no backpack), and the G-9 had increments of 10.4%, 9%, and 9% (p < 0.001), respectively. The G-9 did not prolong their total stance time (p > 0.05), unlike the G-5 (p = 0.001). When running, total stance time increased 15% (p < 0.001) and 8.5% (p < 0.001) proportionally to the relative load carried, in the G-5 and G-9, respectively. Peak GRF did not increase in any group when running or landing from a jump over an obstacle. It was found that GRF was affected by the backpack load when walking and running. However, when landing from a jump with the backpack, schoolchildren smoothed the landing by prolonging the reception time and thus avoiding GRF peak magnitudes.

Podiatric and Stabilographic Examinations of the Effects of School Bag Carrying in Children Aged 11 to 15 Years

“…An example confirming the results obtained in this study is the research conducted by Barbosa et al in groups of children aged 10 to 11 and 14 to 15 years. The results showed that the load caused by the backpack influences the ground reaction forces during walking and running [4]. Similar results were obtained by Ahmad and Barbosa after conducting a study on 48 primary school students performing four trials (carrying backpacks weighing 0%, 10%, and 15% of their body weight) over a distance of 10 m. The children walked slower and with a lower number of steps per minute than in the other three conditions.…”

“…Child obesity can weaken the structure and function of the foot, exposing children to pain and discomfort in the feet [2,3]. An external load in the form of a school backpack, often used by children during the school period, may also have a negative impact on joints, bone health, and body posture [4]. According to reports in the literature, the prevention of backpack-related musculoskeletal problems in primary school students is a serious problem [5].…”

Einfluss des Schulrucksackgewichtes bei Grundschulkindern: Gang, Muskelaktivität, Haltung und Stabilität

“…In unserer Studie über den Effekt des Rucksackgewichts auf die Muskelaktivität und Gelenkrotation beim Gehen sowie die Standstabilität von Grundschulkindern, lag die Traglast bei durchschnittlich 15,0 (SD 2,7) % des Körpergewichts. Dieser Wert ist vergleichbar mit [ 3 , 11 ] bzw. niedriger [ 29 ] als in vorherigen Studien zur Belastung durch den Schulrucksack angegeben.…”

Influence of School Backpack Load as a Variable Affecting Gait Kinematics among Seven-Year-Old Children

“…To date, there is no evidenced limit on the weight of a school BP that can safely be used by school-aged children. The weight of a school BP varies depending on a child’s age and education level [ 26 , 27 , 28 ].…”