January 2022


…Carrying a backpack can increase reactive forces on the soil and plantar pressure, and this increase can be conditioned by the child’s educational level. The increase in ground reaction force (GRF) was noted while children carried a backpack weighing only 7.5% of their body weight. Thus, the increased GRF may be responsible for the higher level of knee flexion observed at further distances and may be a strategy to compensate for the inability of the ankle dorsiflexors to attenuate the impact forces. In fact, such protective behavior, when carrying a backpack, can generate smaller relative magnitudes of impact and propulsive forces when compared to the ‘no-load’ condition. The changes in walking speed and double support time described above could be used to not only maintain stability but also assist in shock absorption.

When carrying a backpack on a single shoulder, despite changes induced in the posture, the body adapts to the asymmetric placement of the load, finding a new dynamic balance that is not significantly different compared with the use of 2 handles. These adaptations cancel out a possible increase in the loading rate, even in children with scoliosis.

The analysis of GRF based on backpack use is of substantial importance because high levels of GRF are commonly associated with several health problems, such as lower limb injuries, degradation of articular cartilage, and injuries at the spine level. Mechanical forces influence spinal growth, and high loading rates can negatively affect bone health. These potential influences have gained emphasis because it is children of growing age who primarily use backpacks on a daily basis…

Excerpted from: Barbosa J, Marques MC, Neiva HP, et al. Impact of overloaded school backpacks: an emerging problem. Open Sports Sciences J. 2021;14:76-81. DOI: 10.2174/1875399X02114010076. Use is per CC BY 4.0.

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