title: Hormonal responses during two different concurrent-training trials in youth elite soccer players: does changing the organization of training impact the hormonal response to concurrent exercise?
abstract: BACKGROUND
  There are no data describing the acute hormonal responses to concurrent-training programmes in youth elite soccer players. Therefore, the aim of this study was to describe the total testosterone (T), cortisol (C), and growth hormone (hGH) responses during two same-day concurrent-training (CT) trials in elite soccer players.
  
  
  METHODS
  Thirteen youth elite players (age: 17.0±0.2 years; height, 1.80±0.07 m; body mass, 73.1±5.7 kg; V̇O2max, 64.4±4.8 mL-1.kg-1.min-1) from an English premier league soccer club completed two CT trials. "Trial 1" (CT1); E (10.30 a.m.) followed by S (02.00 p.m.) and Trial 2 (CT2); strength-training (S) 09.00 a.m. followed by a soccer-specific endurance-training session (E) at 10.30 a.m. Venous blood samples were collected at 5 time-points around training and food intake (T1; 08.00 a.m., T2; 09.45h, T3; 12.30h, T4; 01.45 p.m. and T5; 03.15 p.m.) and analyzed for T (nmol/L) and C (nmol/L) and hGH (ug/L).
  
  
  RESULTS
  There was no main effects found between exercise conditions for any hormones (T; P=0.22, C; P=0.07, hGH; P=0.21). Effect size analysis revealed a moderate effect for T at T3 (ES=0.63, CT1; 18.4±3.8, CT2; 15.7±4.7 nmol/L-1). A moderate effect for T Area Under the Curve (AUC) was observed between conditions (CT1; 300±76 versus CT2; 244±81 [AU]; ES=0.71). A moderate effect was apparent for C concentrations T4 in (ES=-0.95, CT1; 230±69, CT2; 314±105 nmol/L-1). Moderate effect sizes were observed at T3 and T4 (ES=0.82, CT1; 1.28±1.17, CT2; 0.47±0.75, ES=0.72, CT1; 0.11±0.05, CT2; 0.07±0.06 ug/L-1 respectively). A moderate effect for hGH AUC was observed between trials (CT1; 14±11 versus CT2; 5±9; [AU], ES=-1.08).
  
  
  CONCLUSIONS
  The organisation of the concurrent-training protocols used in this study has a negligible impact upon the acute T, C and hGH in youth elite soccer players.
authors.affiliation: School of Education, Leisure and Sport Studies, Liverpool John Moores University, Liverpool, UK - k.j.enright@ljmu.ac.uk.|Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK - k.j.enright@ljmu.ac.uk.|Department of Medical and Exercise Science, Wolverhampton Wanderers Football Club, Wolverhampton, UK - k.j.enright@ljmu.ac.uk.
authors.forename: Kevin
authors.initials: K
authors.lastname: Enright
authors.affiliation: Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK.
authors.forename: James
authors.initials: J
authors.lastname: Morton
authors.affiliation: Department of Medical and Exercise Science, Wolverhampton Wanderers Football Club, Wolverhampton, UK.|Huddersfield Town Football Club, Training Centre, Huddersfield, UK.
authors.forename: John
authors.initials: J
authors.lastname: Iga
authors.affiliation: Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK.
authors.forename: Barry
authors.initials: B
authors.lastname: Drust
mesh_terms: D000293:Adolescent; D019540:Area Under Curve; D054874:Athletic Performance / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D006728:Hormones / Q000378:metabolism*; D019382:Human Growth Hormone / Q000378:metabolism; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism; D008297:Male; D010807:Physical Endurance / Q000502:physiology*; D055070:Resistance Training / Q000379:methods*; D012916:Soccer / Q000502:physiology*; D013739:Testosterone / Q000378:metabolism
chemical_list: D006728:Hormones; D019382:Human Growth Hormone; D013739:Testosterone; D006854:Hydrocortisone