title: Mechanical, hormonal, and hypertrophic adaptations to 10 weeks of eccentric and stretch-shortening cycle exercise training in old males.
abstract: The growth promoting effects of eccentric (ECC) contractions are well documented but it is unknown if the rate of stretch per se plays a role in such muscular responses in healthy aging human skeletal muscle. We tested the hypothesis that exercise training of the quadriceps muscle with low rate ECC and high rate ECC contractions in the form of stretch-shortening cycles (SSCs) but at equal total mechanical work would produce rate-specific adaptations in healthy old males age 60-70. Both training programs produced similar improvements in maximal voluntary isometric (6%) and ECC torque (23%) and stretch-shortening cycle function (reduced contraction duration [24%] and enhanced elastic energy storage [12%]) (p<0.05). The rate of torque development increased 30% only after SSC exercise (p<0.05). Resting testosterone and cortisol levels were unchanged but after each program the acute exercise-induced cortisol levels were 12-15% lower (p<0.05). Both programs increased quadriceps size 2.5% (p<0.05). It is concluded that both ECC and SSC exercise training produces favorable adaptations in healthy old males' quadriceps muscle. Although the rate of muscle tension during the SSC vs. ECC contractions was about 4-fold greater, the total mechanical work seems to regulate the hypetrophic, hormonal, and most of the mechanical adaptations. However, SSC exercise was uniquely effective in improving a key deficiency of aging muscle, i.e., its ability to produce force rapidly.
authors: Institute of Sport Sciences and Physical Education, University of Pécs, Ifjúság útja 6., 7624 Pécs, Hungary. Electronic address: vaczi@gamma.ttk.pte.hu.
authors: Márk
authors: M
authors: Váczi
authors: Diagnostic Center of Pécs, Rét utca 2., 7623 Pécs, Hungary. Electronic address: szilvia.anett.nagy@gmail.com.
authors: Szilvia A
authors: SA
authors: Nagy
authors: Institute of Laboratory Medicine, University of Pécs, Szigeti út 2., 7624 Pécs, Hungary. Electronic address: koszegit@freemail.hu.
authors: Tamás
authors: T
authors: Kőszegi
authors: Institute of Sport Sciences and Physical Education, University of Pécs, Ifjúság útja 6., 7624 Pécs, Hungary. Electronic address: ambrusmira@freemail.hu.
authors: Míra
authors: M
authors: Ambrus
authors: Diagnostic Center of Pécs, Rét utca 2., 7623 Pécs, Hungary. Electronic address: peter.bogner@gmail.com.
authors: Péter
authors: P
authors: Bogner
authors: Diagnostic Center of Pécs, Rét utca 2., 7623 Pécs, Hungary; MTA-PTE Clinical Neuroscience MR Research Group, Rét utca 2., 7623 Pécs, Hungary. Electronic address: petzinger.gabor@gmail.com.
authors: Gábor
authors: G
authors: Perlaki
authors: Diagnostic Center of Pécs, Rét utca 2., 7623 Pécs, Hungary; MTA-PTE Clinical Neuroscience MR Research Group, Rét utca 2., 7623 Pécs, Hungary. Electronic address: gergo.orsi@gmail.com.
authors: Gergely
authors: G
authors: Orsi
authors: Department of Radiography, Faculty of Health Sciences, University of Pécs, 7400 Kaposvár, Hungary. Electronic address: katalin.toth90@gmail.com.
authors: Katalin
authors: K
authors: Tóth
authors: Center for Human Movement Sciences, University Medical Center Groningen, A. Deusinglaan 1, 9700 AD Groningen, The Netherlands; Faculty of Health and Life Sciences, Northumbria University, Newcastle-upon-Tyne, UK. Electronic address: t.hortobagyi@umcg.nl.
authors: Tibor
authors: T
authors: Hortobágyi
mesh_terms: D000222:Adaptation, Physiological; D000367:Age Factors; D000368:Aged; D000375:Aging / Q000097:blood / Q000502:physiology*; D015415:Biomarkers / Q000097:blood; D001696:Biomechanical Phenomena; D006801:Humans; D006814:Hungary; D006854:Hydrocortisone / Q000097:blood; D006984:Hypertrophy; D007537:Isometric Contraction; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength; D009929:Organ Size; D052097:Quadriceps Muscle / Q000378:metabolism / Q000502:physiology*; D055070:Resistance Training / Q000379:methods*; D012737:Sex Factors; D013739:Testosterone / Q000097:blood; D013997:Time Factors; D019415:Torque; D016896:Treatment Outcome
chemical_list: D015415:Biomarkers; D013739:Testosterone; D006854:Hydrocortisone
keywords: Aging; Elastic energy; Explosive strength; Hormone; Hypertrophy; Stretch-shortening cycle