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Open AccessArticle

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

1
Department of Sport Sciences, University of Beira Interior, 6201-001 Covilhã, Portugal
2
Research Center in Sports Sciences, Health Sciences and Human Development, CIDESD, 6201-001 Covilhã, Portugal
3
Department of Health Sciences, Public University of Navarre, Navarrabiomed, CIBER de Fragilidad y Envejecimiento Saludable (CB16/10/00315), 31006 Pamplona, Navarra, Spain
4
Grupo GICAEDS, Programa de Cultura Física, Deporte y Recreación, Universidad Santo Tomás, Bogotá 110311, Colombia
5
Laboratory of Human Performance, Quality of Life and Wellness Research Group, Department of Physical Activity Sciences, Universidad de Los Lagos, Osorno 5290000, Chile
*
Author to whom correspondence should be addressed.
Int. J. Environ. Res. Public Health 2019, 16(24), 5154; https://doi.org/10.3390/ijerph16245154
Received: 23 October 2019 / Revised: 6 December 2019 / Accepted: 13 December 2019 / Published: 17 December 2019
(This article belongs to the Special Issue Health, Exercise and Sports Performance)
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. View Full-Text
Keywords: backpack; children; load-carriage; gait; ground reaction forces backpack; children; load-carriage; gait; ground reaction forces
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MDPI and ACS Style

Barbosa, J.P.; Marques, M.C.; Neiva, H.P.; Esteves, D.; Alonso-Martínez, A.M.; Izquierdo, M.; Ramirez-Campillo, R.; Alvarez, C.; Marinho, D.A. Effects of Backpacks on Ground Reaction Forces in Children of Different Ages When Walking, Running, and Jumping. Int. J. Environ. Res. Public Health 2019, 16, 5154.

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