title: Regular Football Practice Improves Autonomic Cardiac Function in Male Children.
abstract: BACKGROUND
  The role of the autonomic nervous system (ANS) in the cardiovascular regulation is of primal importance. Since it has been associated with adverse conditions such as cardiac arrhythmias, sudden death, sleep disorders, hypertension and obesity.
  
  
  OBJECTIVE
  The present study aimed to investigate the impact of recreational football practice on the autonomic cardiac function of male children, as measured by heart rate variability.
  
  
  METHODS
  Forty-seven male children aged 9 - 12 years were selected according to their engagement with football oriented practice outside school context. The children were divided into a football group (FG; n = 22) and a control group (CG; n = 25). The FG had regular football practices, with 2 weekly training sessions and occasional weekend matches. The CG was not engaged with any physical activity other than complementary school-based physical education classes. Data from physical activity, physical fitness, and heart rate variability measured in time and frequency domains were obtained.
  
  
  RESULTS
  The anthropometric and body composition characteristics were similar in both groups (P > 0.05). The groups were also similar in time spent daily on moderate-to-vigorous physical activities (FG vs. CG: 114 ± 64 vs. 87 ± 55 minutes; P > 0.05). However, the FG performed better (P < 0.05) in Yo-Yo intermittent endurance test (1394 ± 558 vs. 778 ± 408 m) and 15-m sprint test (3.06 ± 0.17 vs. 3.20 ± 0.23 s). Also, the FG presented enhanced autonomic function. Significant differences were detected (P < 0.05) between groups for low frequency normalized units (38.0 ± 15.2 vs. 47.3 ± 14.2 n.u (normalized units)), high frequency normalized units (62.1 ± 15.2 vs. 52.8 ± 14.2 n.u.), and LF:HF ratio (0.7 ± 0.4 vs. 1.1 ± 0.6 ms(2)).
  
  
  CONCLUSIONS
  Children engaged with regular football practice presented enhanced physical fitness and autonomic function, by increasing vagal tone at rest.
authors.affiliation: Centre of Research, Education, Innovation and Intervention in Sport, Faculty of Sport, University of Porto, Porto, Portugal.
authors.forename: Luis
authors.initials: L
authors.lastname: Fernandes
authors.affiliation: Research Centre in Physical Activity, Health and Leisure, Faculty of Sport, University of Porto, Portugal.
authors.forename: Jose
authors.initials: J
authors.lastname: Oliveira
authors.affiliation: Research Centre in Physical Activity, Health and Leisure, Faculty of Sport, University of Porto, Portugal.
authors.forename: Luisa
authors.initials: L
authors.lastname: Soares-Miranda
authors.affiliation: Centre of Research, Education, Innovation and Intervention in Sport, Faculty of Sport, University of Porto, Porto, Portugal.
authors.forename: Antonio
authors.initials: A
authors.lastname: Rebelo
authors.affiliation: Portuguese Football Federation, Health and Performance Unit, Lisbon, Portugal.
authors.forename: Joao
authors.initials: J
authors.lastname: Brito
keywords: Heart rate; Physical Education; Soccer