title: Differences in physical performance between U-20 and senior top-level Brazilian futsal players.
abstract: BACKGROUND
  The aim of this study was to compare performance in the Yo-Yo IR1, 20-meter sprint, COD test, loaded and unloaded lower-limb muscle power tests (squat jump [SJ], countermovement jump [CMJ] and jump squat [JS] tests), as well as resting and exercise heart rate variability parameters in high-level senior professional and under-20 (U-20) futsal players.
  
  
  METHODS
  All the players (18 senior and 15 U-20 male players) performed the Yo-Yo Intermittent Recovery Test level 1 (Yo-Yo IR1), 20-m sprint, COD test, loaded and unloaded lower-limb power tests (SJ, CMJ and JS tests), as well as resting and post-exercise log-transformed root-mean-square difference of successive normal RR intervals (lnRMSSD) recording. The t-test for independent samples and magnitude-based inference were used to compare the groups.
  
  
  RESULTS
  Seniors were likely to very likely superior than U-20 in the Yo-Yo IR1 (1506.7±287.1 and 1264.0±397.9 m, P<0.05), and resting (3.43±0.32 and 3.21±0.37 ms) and post-exercise lnRMSSD (2.95±0.39 and 2.48±0.59 ms, P<0.05). Conversely, U-20 players performed very likely to almost certainly better than seniors in the relative mean propulsive power (10.39±1.60 and 9.05±1.57 W/kg, P<0.05), 20-m sprint time (2.92±0.10 and 3.05±0.10 s, P<0.05) and COD (5.50±0.15 and 5.71±0.22 s, P<0.05).
  
  
  CONCLUSIONS
  Findings from this cross-sectional study indicate that long-term exposure to futsal may lead to improvement in the aerobic fitness and cardiac autonomic regulation, while impairing the muscle power and speed performance of players. Future longitudinal studies are necessary to confirm the occurrence of such concurrent training adaptations.
authors.affiliation: Nucleus of High Performance in Sport (NAR), São Paulo, Brazil - fabioy_nakamura@yahoo.com.br.
authors.forename: Fábio Y
authors.initials: FY
authors.lastname: Nakamura
authors.forename: Lucas A
authors.initials: LA
authors.lastname: Pereira
authors.forename: César C
authors.initials: CC
authors.lastname: Cal Abad
authors.forename: Ronaldo
authors.initials: R
authors.lastname: Kobal
authors.forename: Katia
authors.initials: K
authors.lastname: Kitamura
authors.forename: Hamilton
authors.initials: H
authors.lastname: Roschel
authors.forename: Felipe
authors.initials: F
authors.lastname: Rabelo
authors.forename: Wilson A
authors.initials: WA
authors.lastname: Souza
authors.forename: Irineu
authors.initials: I
authors.lastname: Loturco
mesh_terms: D000064:Acclimatization; D000293:Adolescent; D000328:Adult; D054874:Athletic Performance / Q000502:physiology*; D001341:Autonomic Nervous System; D001938:Brazil; D003430:Cross-Sectional Studies; D005080:Exercise Test / Q000379:methods*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D035002:Lower Extremity; D008297:Male; D012146:Rest; D012420:Running / Q000502:physiology; D012916:Soccer / Q000502:physiology; D055815:Young Adult