Recreational soccer training improves heart-rate variability indices and physical performance in untrained healthy adolescent

The aim of this study was to evaluate the effects of soccer training on short-term heart-rate variability, blood pressure, and physical fitness in untrained healthy adolescents. Twenty-two adolescent boys took part in this study: 11 boys were randomly assigned to participate in an 8-week soccer training and 11 boys served as a control group. Soccer exhibited significant increases in high-frequency power (difference 52.9%, P = 0.03, effect size: ES = 1.2), root mean squared of the standard deviation rMSSD (10.8%, P = 0.02, ES = 1), and a significant decrease in sympathetic activity LF (26.3%, P = 0.004, ES = 1.4). The control group showed an increase in rMSSD (9.4%, P = 0.05, ES = 1). The soccer group showed increases in estimated aerobic fitness (30.9%, P = 0.001, ES = 1.50) and 20-m sprint performance (4.1%, P = 0.004, ES = 0.8) with a trend to an improvement in horizontal jumping (3.8%, P = 0.15, ES = 0.8). In conclusion, soccer-based training improved measures of both physical fitness and autonomic function making soccer an effective training strategy for improving health-related fitness measures in untrained adolescents.