Catalogo Articoli (Spogli Riviste)

OPAC HELP

Titolo:
Selective muscle hypertrophy, changes in EMG and force, and serum hormonesduring strength training in older women
Autore:
Hakkinen, K; Pakarinen, A; Kraemer, WJ; Hakkinen, A; Valkeinen, H; Alen, M;
Indirizzi:
Univ Jyvaskyla, Neuromuscular Res Ctr, Jyvaskyla 40351, Finland Univ Jyvaskyla Jyvaskyla Finland 40351 Res Ctr, Jyvaskyla 40351, Finland Univ Jyvaskyla, Dept Biol Phys Activ, Jyvaskyla 40351, Finland Univ Jyvaskyla Jyvaskyla Finland 40351 s Activ, Jyvaskyla 40351, Finland Univ Oulu, Dept Clin Chem, Oulu 90220, Finland Univ Oulu Oulu Finland 90220 v Oulu, Dept Clin Chem, Oulu 90220, Finland Ball State Univ, Human Performance Lab, Muncie, IN 47306 USA Ball State Univ Muncie IN USA 47306 Performance Lab, Muncie, IN 47306 USA Cent Hosp, Dept Phys Med & Rehabil, Jyvaskyla 40620, Finland Cent Hosp Jyvaskyla Finland 40620 ed & Rehabil, Jyvaskyla 40620, Finland Univ Jyvaskyla, Dept Hlth Sci, Jyvaskyla 40351, Finland Univ Jyvaskyla Jyvaskyla Finland 40351 lth Sci, Jyvaskyla 40351, Finland Kuopio Univ Hosp, Dept Phys Med & Rehabil, Kuopio 70211, Finland Kuopio Univ Hosp Kuopio Finland 70211 d & Rehabil, Kuopio 70211, Finland
Titolo Testata:
JOURNAL OF APPLIED PHYSIOLOGY
fascicolo: 2, volume: 91, anno: 2001,
pagine: 569 - 580
SICI:
8750-7587(200108)91:2<569:SMHCIE>2.0.ZU;2-9
Fonte:
ISI
Lingua:
ENG
Soggetto:
HEAVY RESISTANCE EXERCISE; HIGH-INTENSITY STRENGTH; CROSS-SECTIONAL AREA; SKELETAL-MUSCLE; GROWTH-HORMONE; ELDERLY MEN; NEURAL ACTIVATION; HUMAN QUADRICEPS; RESPONSES; TESTOSTERONE;
Keywords:
aging; muscle; endocrine functions; resistance training; selective hypertrophy; electromyogram;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
45
Recensione:
Indirizzi per estratti:
Indirizzo: Hakkinen, K Univ Jyvaskyla, Neuromuscular Res Ctr, POB 35, Jyvaskyla 40351, Finland Univ Jyvaskyla POB 35 Jyvaskyla Finland 40351 40351, Finland
Citazione:
K. Hakkinen et al., "Selective muscle hypertrophy, changes in EMG and force, and serum hormonesduring strength training in older women", J APP PHYSL, 91(2), 2001, pp. 569-580

Abstract

Effects of strength training (ST) for 21 wk were examined in 10 older women (64 +/- 3 yr). Electromyogram, maximal isometric force, one-repetition maximum strength, and rate of force development of the leg extensors, muscle cross-sectional area (CSA) of the quadriceps femoris (QF) and of vastus lateralis (VL), medialis (VM), intermedius (VI) and rectus femoris (RF) throughout the lengths of 3/12-12/15 (Lf) of the femur, muscle fiber proportion and areas of types I, IIa, and IIb of the VL were evaluated. Serum hormone concentrations of testosterone, growth hormone (GH), cortisol, and IGF-I were analyzed for the resting, preexercise, and postexercise conditions. Afterthe 21-wk ST, maximal force increased by 37% (P < 0.001) and 1- RM by 29% (P < 0.001), accompanied by an increase (P < 0.01) in rate of force development. The integrated electromyograms of the vastus muscles increased (P < 0.05). The CSA of the total QF increased (P < 0.05) throughout the length ofthe femur by 5-9%. The increases were significant (P < 0.05) at 7/15-12/15Lf for VL and at 3/15-8/15 Lf for VM, at 5/15-9/15 for VI and at 9/15 (P <0.05) for RF. The fiber areas of type I (P < 0.05), IIa (P < 0.001), and IIb (P < 0.001) increased by 22-36%. No changes occurred during ST in serum basal concentrations of the hormones examined, but the level of testosterone correlated with the changes in the CSA of the QF (r = 0.64, P < 0.05). Anacute increase of GH (P < 0.05), remaining elevated up to 30 min (P < 0.05) postloading, was observed only at posttraining. Both neural adaptations and the capacity of skeletal muscle to undergo training-induced hypertrophy even in older women explain the strength gains. The increases in the CSA ofthe QF occurred throughout its length but differed selectively between theindividual muscles. The serum concentrations of hormones remained unaltered, but a low level of testosterone may be a limiting factor in training-induced muscle hypertrophy. The magnitude and time duration of the acute GH response may be important physiological indicators of anabolic adaptations during strength training even in older women.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 04/04/20 alle ore 08:55:22