title: Hormonal responses from concentric and eccentric muscle contractions.
abstract: Intense resistance exercise can acutely increase testosterone (T), free testosterone (FT), and growth hormone (GH) concentrations, but there are few investigations concerning acute endocrine responses to concentric (CON) and eccentric (ECC) contractile actions.
  
  
  OBJECTIVE
  The purpose of the study was to compare acute anabolic hormonal responses to bouts of dynamic CON and ECC contractions from multiple exercises at the same absolute load.
  
  
  METHODS
  Ten young men (age: 24.7 +/- 1.2 yr, weight: 85.45 +/- 24.2 kg, and height: 178 +/- 0.2 cm) completed two trials in counterbalanced fashion consisting of only CON or ECC contractions at the same absolute workload. Subjects performed four sets of 12 repetitions of bench press, leg extension, military press, and leg curl at 80% of a 10-repetition maximum with 90-s rest periods. Blood samples were collected pre-, post-, and 15-min postexercise.
  
  
  RESULTS
  There were significant increases in GH, T, and FT and lactate for both trials, but only GH and lactate were greater for the CON trial.
  
  
  CONCLUSIONS
  CON exercise increases GH concentrations to a much greater extent than ECC exercise at the same absolute load, and it is likely that greater GH responses were related to intensity rather than mode of contraction. Also, CON and ECC dynamic contraction trials at the same absolute workload elicited similar small but significant increases in T and FT, indicating that the greater metabolic stress produced by during the CON trial did not affect these hormone responses.
authors.affiliation: Department of Kinesiology and Health Studies, Southeastern Louisiana University, Hammond, USA. Durandrj@pbrc.edu
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Durand
authors.forename: V Daniel
authors.initials: VD
authors.lastname: Castracane
authors.forename: Daniel B
authors.initials: DB
authors.lastname: Hollander
authors.forename: James L
authors.initials: JL
authors.lastname: Tryniecki
authors.forename: Marcas M
authors.initials: MM
authors.lastname: Bamman
authors.forename: Sarah
authors.initials: S
authors.lastname: O'Neal
authors.forename: Edward P
authors.initials: EP
authors.lastname: Hebert
authors.forename: Robert R
authors.initials: RR
authors.lastname: Kraemer
mesh_terms: D000328:Adult; D015444:Exercise / Q000502:physiology*; D019382:Human Growth Hormone / Q000097:blood*; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D013739:Testosterone / Q000097:blood*; D014891:Weight Lifting
chemical_list: D019382:Human Growth Hormone; D019344:Lactic Acid; D013739:Testosterone