Objective: This study aimed to assess the relative load of the midfoot and the metatarsals of both feet when schoolchildren walked with backpacks of different loads.
Methods: A group of 12 healthy girls (9.9 ± 0.8 years; 33.8 ± 6.7 kg, 1.40 ± 0.10 m) walked barefoot to assess plantar pressures during gait without load (L0%) and with a loaded backpack equal to 10% (L10%) and 20% (L20%) of their body weight. A Footscan® system (RSscan International, Belgium) was used to determine the contact area and relative pressure impulse in the midfoot and metatarsals on the dominant (DL) and non-dominant legs (NL).
Results: The effect of load was significant for the contact area of the midfoot for both NL (p = 0.013) and DL (p = 0.001). In the metatarsals, there was significantly greater relative impulse during L10% compared to L0% in the first (p = 0.041) and second (p = 0.050) metatarsals of the DL. Comparing the NL and DL showed significantly greater relative impulse on the DL in the fourth metatarsal during L10% (p = 0.023), greater contact area in the fifth metatarsal during L0% (p = 0.050), and greater impulse in the midfoot during L20% (p = 0.028) on the NL.
Conclusions: The school backpack load influences relative plantar pressure distribution, especially in the midfoot. Further, our findings suggest greater propulsion of the DL and supporting function of the NL.
Keywords: biomechanics; gait; health; kinetics; laterality; overload.