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- Effects of Backpacks on Ground Reaction Forces in Children of Different Ages When Walking, Running, and JumpingPublication . Barbosa, João P.; Marques, MC; Neiva, Henrique; Esteves, Dulce; Alonso-Martínez, Alicia M; Izquierdo, Mikel; Ramirez-Campillo, Rodrigo; Alvarez, Cristian; Marinho, DanielBackpacks 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.
- High-Speed Resistance Training in Older Women: The Role of SupervisionPublication . Ramirez-Campillo, Rodrigo; Martínez, Cristian; De La Fuente, Carlos I.; Cadore, Eduardo; Marques, MC; Nakamura, Fábio; Loturco, Irineu; Caniuqueo, Alexis; Cañas, Rodrigo; Izquierdo, MikelOlder women participated in a 12-week high-speed resistance training program under two supervisor-to-subject ratio methods (i.e., high versus low supervision) to assess its effects on muscle strength, power, functional performance, and quality of life assessed before (T1) and after (T2) intervention. Women were divided into either the control group (CG, n = 15), high supervision group (HSG, n = 30), or low supervision group (LSG, n = 28). The training program included exercises requiring high-speed concentric muscle actions. No differences were observed among groups at T1. Between T1 and T2, the HSG showed a higher (p < .05) improvement in muscle strength (ES = 0.36-1.26), power (ES = 0.5-0.88), functional performance (ES = 0.52-0.78), and quality of life (ES = 0.44-0.82) compared with LSG and CG. High-speed resistance training under closer supervision is more effective for improving muscle strength, power, functional performance, and quality of life in older women.