RESUMEN
There is only limited evidence to suggest that training during childhood produces greater adaptations than at other ages. The aim of this study was to examine the effects of plyometric training (12 weeks, twice/week, 20 min/day) on physical fitness (PF) and gross motor coordination (GMC) in schoolboys aged 7-9 years. A total of 116 boys were assigned to two groups: plyometric training group (PT,n = 73) and control group (CG,n = 43). The CG maintained their normal daily activities. The PT consisted of twice-weekly exercises on nonconsecutive days for twelve weeks under monitored and controlled conditions. PF (handgrip strength, standing long jump (SLJ), curl-ups, sit and reach, square-test, running speed, and 1 mile run test), GMC, Korper-koordinations-test fur Kinder (KTK), and body mass index (BMI) were assessed. The main results through a 2 × 2 (time × groups) repeated measures analysis variance demonstrated a significant time effect that improves PF and GMC according to the direction of the measure. A group effect was observed only in the abdominal strength test (CG = 12.06% and PT = 17.04%) and moving sideways (CG = 11.1% and PT = 12.4%) showing that independent of the group there was an improvement. A significant interaction effect (time × groups) was observed in the flexibility test (CG = -2.7% and PT = 3.5%) and STJ (CG = 3.1% and PT = 18.5%), as well as jumping sideways (CG = 16.3% and PT = 17.4%) and overall GMC score (CG = 9.8% and PT = 15.9%), showing that gains in these variables were greater in the PT group. The results suggest that 12 weeks of PT improve components of gross motor coordination and health-related physical fitness in children.
