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Skeletal muscle oxidative function in vivo and ex vivo in athletes with marked hypertrophy from resistance training

Salvadego, Desy and Domenis, Rossana and Lazzer, Stefano and Porcelli, Simone and Rittweger, Jörn and Rizzo, Giovanni and Mavelli, Irene and Šimunicˇ, Bostjan and Pišot, Rado and Grassi, Bruno (2013) Skeletal muscle oxidative function in vivo and ex vivo in athletes with marked hypertrophy from resistance training. Journal of Applied Physiology (114), pp. 1527-1535. American Physiological Society. DOI: 10.1152/japplphysiol.00883.2012 ISSN 8750-7587

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Abstract

RESISTANCE TRAINING PROGRAMS have been developed with the aim of improving variables of muscle function such as strength, power, speed, local muscular endurance, coordination, and flexibility (21). Resistance training is now considered an important part of training and rehabilitation programs for healthy subjects and for various types of patients, such as cardiac patients (45), patients with pulmonary diseases (10), patients undergoing prolonged bed-rest periods (2), or elderly subjects (28). In these populations, the combination of resistance training with the more conventional endurance exercise improves the patients’ outcomes and quality of life (45). An increase in the cross-sectional area of skeletal muscle fibers and a shift of fiber-type distribution toward type 2 fibers are typical adaptations induced by resistance training; these adaptations enhance the muscle force-generating potential (12) but could represent an impairment to skeletal muscle oxidative metabolism. On the other hand, muscles with higher maximal force would need to recruit a lower number of motor units, and therefore more oxidative (and more efficient) muscle fibers (20, 26). According to other authors, strength training may increase skeletal muscle efficiency (4) and enhance skeletal muscle “metabolic stability” (50). Other studies reported, after resistance training, unchanged values of maximal O2 uptake (V˙ O2) (6), as well as unchanged (19) or lower (42, 43) mitochondrial volume density, oxidative enzyme activity, and capillary density in the hypertrophic muscles. Thus the specific effects of resistance training, with the related changes in muscle phenotype, on oxidative metabolism appear difficult to reconcile in a unifying scenario. The aim of the present study was to determine whether increases in muscle mass induced by chronic resistance training are associated, in humans, with alterations in skeletal muscle oxidative function and aerobic performance. Experiments were carried out on a group of resistance-trained athletes (RTA), in whom muscle adaptations to resistance exercise are expected to be particularly marked. An integrative approach was applied by analyzing oxidative metabolism at different levels, spanning from pulmonary gas exchange to skeletal muscle function and mitochondrial respiration. Oxidative function was assessed in vivo during incremental cycle ergometer (CE) exercise and dynamic knee extension (KE) exercise with one leg (3). During KE, the recruitment of a relatively small muscle mass, i.e., the quadriceps femoris of one leg, significantly reduces constraints to oxidative function deriving from cardiovascular O2 delivery, thereby allowing a more direct assessment of quadriceps muscle oxidative capacity in vivo. The intrinsic properties of mitochondria were assessed ex vivo in permeabilized muscle fibers obtained by biopsy by high-resolution respirometry (36). We hypothesized, in RTA vs. control subjects (CTRL), an impaired skeletal muscle oxidative function in vivo and an impaired mitochondrial respiratory function ex vivo.

Item URL in elib:https://elib.dlr.de/82715/
Document Type:Article
Title:Skeletal muscle oxidative function in vivo and ex vivo in athletes with marked hypertrophy from resistance training
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Salvadego, DesyUniversity of UdineUNSPECIFIED
Domenis, RossanaUniversity of UdineUNSPECIFIED
Lazzer, StefanoUniversity of UdineUNSPECIFIED
Porcelli, SimoneUniversity of UdineUNSPECIFIED
Rittweger, Jörnjoern.rittweger (at) dlr.deUNSPECIFIED
Rizzo, GiovanniNational Research Council, MilanUNSPECIFIED
Mavelli, IreneUniversity of UdineUNSPECIFIED
Šimunicˇ, BostjanUniversity of UdineUNSPECIFIED
Pišot, RadoUniversity of PrimorskaUNSPECIFIED
Grassi, BrunoUniversity of UdineUNSPECIFIED
Date:2013
Journal or Publication Title:Journal of Applied Physiology
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
DOI :10.1152/japplphysiol.00883.2012
Page Range:pp. 1527-1535
Editors:
EditorsEmail
Dempsey, JerryUNSPECIFIED
Publisher:American Physiological Society
ISSN:8750-7587
Status:Published
Keywords:skeletal muscle hypertrophy; mitochondrial respiration; oxidative metabolism during exercise
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Research under Space Conditions
DLR - Research area:Raumfahrt
DLR - Program:R FR - Forschung unter Weltraumbedingungen
DLR - Research theme (Project):R - Vorhaben Systemphysiologie
Location: Köln-Porz
Institutes and Institutions:Institute of Aerospace Medicine > Space Physiology
Deposited By: Becker, Christine
Deposited On:20 Jun 2013 08:19
Last Modified:06 Sep 2019 15:27

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