title: The influence of muscle action on the acute growth hormone response to resistance exercise and short-term detraining.
abstract: The effects of resistance training with concentric or concentric-eccentric muscle actions on the acute hormonal response to a resistance exercise protocol was investigated. Thirty-two men completed a 19 week lower-body resistance training program (consisting of the leg press and leg extension exercises) in which they (1) performed concentric actions only (CON); (2) performed both concentric and eccentric actions (CON-ECC); (3) performed double concentric actions for each repetition (CON-CON); or (4) did not exercise. Following training each subject performed two exercise tests consisting of three sets of 30 isokinetic concentric (day 1) and eccentric (day 2) knee extensions separated by 48 h. The exercise tests were repeated following 4 weeks of detraining. Blood samples were obtained before and after each exercise test. Serum growth hormone (GH) was significantly (P< 0.05) greater for the concentric test in groups CON and CON-CON whereas GH was lower for the concentric test in CON-ECC compared with the eccentric test prior to detraining. Following detraining, GH was greater during the concentric test in CON-ECC than in the eccentric test, whereas no differences were observed between the concentric and eccentric tests in CON and CON-CON and the acute GH response to resistance exercise was attenuated. These data indicate that GH is sensitive to muscle action type with differential responses observed with resistance exercise after short-term detraining.
authors.affiliation: The Human Performance Laboratory, Ball State University, Muncie, IN 47306, USA. wkraemer@bsu.edu
authors.forename: W J
authors.initials: WJ
authors.lastname: Kraemer
authors.forename: G A
authors.initials: GA
authors.lastname: Dudley
authors.forename: P A
authors.initials: PA
authors.lastname: Tesch
authors.forename: S E
authors.initials: SE
authors.lastname: Gordon
authors.forename: B M
authors.initials: BM
authors.lastname: Hather
authors.forename: J S
authors.initials: JS
authors.lastname: Volek
authors.forename: N A
authors.initials: NA
authors.lastname: Ratamess
mesh_terms: D000328:Adult; D015444:Exercise; D013006:Growth Hormone / Q000097:blood*; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D019344:Lactic Acid / Q000097:blood; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D012738:Sex Hormone-Binding Globulin / Q000378:metabolism; D013739:Testosterone / Q000097:blood
chemical_list: D012738:Sex Hormone-Binding Globulin; D019344:Lactic Acid; D013739:Testosterone; D013006:Growth Hormone; D006854:Hydrocortisone