title: Intermittent hypobaric hypoxia combined with aerobic exercise improves muscle morphofunctional recovery after eccentric exercise to exhaustion in trained rats.
abstract: Unaccustomed eccentric exercise leads to muscle morphological and functional alterations, including microvasculature damage, the repair of which is modulated by hypoxia. We present the effects of intermittent hypobaric hypoxia and exercise on recovery from eccentric exercise-induced muscle damage (EEIMD). Soleus muscles from trained rats were excised before (CTRL) and 1, 3, 7, and 14 days after a double session of EEIMD protocol. A recovery treatment consisting of one of the following protocols was applied 1 day after the EEIMD: passive normobaric recovery (PNR), a 4-h daily exposure to passive hypobaric hypoxia at 4,000 m (PHR), or hypobaric hypoxia exposure followed by aerobic exercise (AHR). EEIMD produced an increase in the percentage of abnormal fibers compared with CTRL, and it affected the microvasculature by decreasing capillary density (CD, capillaries per mm2) and the capillary-to-fiber ratio (CF). After 14 days, AHR exhibited CD and CF values similar to those of CTRL animals (789 and 3.30 vs. 746 and 3.06) and significantly higher than PNR (575 and 2.62) and PHR (630 and 2.92). Furthermore, VEGF expression showed a significant 43% increase in AHR when compared with PNR. Moreover, after 14 days, the muscle fibers in AHR had a more oxidative phenotype than the other groups, with significantly smaller cross-sectional areas (AHR, 3,745; PNR, 4,502; and PHR, 4,790 µm2), higher citrate synthase activity (AHR, 14.8; PNR, 13.1; and PHR, 12 µmol·min-1·mg-1) and a significant 27% increment in PGC-1α levels compared with PNR. Our data show that hypoxia combined with exercise attenuates or reverses the morphofunctional alterations induced by EEIMD.NEW & NOTEWORTHYOur study provides new insights into the use of intermittent hypobaric hypoxia combined with exercise as a strategy to recover muscle damage induced by eccentric exercise. We analyzed the effects of hypobaric exposure combined with aerobic exercise on histopathological features of muscle damage, fiber morphofunctionality, capillarization, angiogenesis, and the oxidative capacity of damaged soleus muscle. Most of these parameters were improved after a 2-wk protocol of intermittent hypobaric hypoxia combined with aerobic exercise.
authors.affiliation: Departament de Biologia Cel·lular, Fisiologia i Immunologia, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain; and drizo@ub.edu.
authors.forename: D
authors.identifier: http://orcid.org/0000-0002-9379-7543
authors.initials: D
authors.lastname: Rizo-Roca
authors.affiliation: Departament de Biologia Cel·lular, Fisiologia i Immunologia, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain; and.
authors.forename: J G
authors.initials: JG
authors.lastname: Ríos-Kristjánsson
authors.affiliation: Departament de Biologia Cel·lular, Fisiologia i Immunologia, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain; and.
authors.forename: C
authors.initials: C
authors.lastname: Núñez-Espinosa
authors.affiliation: Research Center in Physical Activity, Health and Leisure, Faculty of Sport, University of Porto, Porto, Portugal.
authors.forename: E
authors.initials: E
authors.lastname: Santos-Alves
authors.affiliation: Research Center in Physical Activity, Health and Leisure, Faculty of Sport, University of Porto, Porto, Portugal.
authors.forename: I O
authors.initials: IO
authors.lastname: Gonçalves
authors.affiliation: Research Center in Physical Activity, Health and Leisure, Faculty of Sport, University of Porto, Porto, Portugal.
authors.forename: J
authors.initials: J
authors.lastname: Magalhães
authors.affiliation: Research Center in Physical Activity, Health and Leisure, Faculty of Sport, University of Porto, Porto, Portugal.
authors.forename: A
authors.initials: A
authors.lastname: Ascensão
authors.affiliation: Departament de Biologia Cel·lular, Fisiologia i Immunologia, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain; and.
authors.forename: T
authors.initials: T
authors.lastname: Pagès
authors.affiliation: Departament de Biologia Cel·lular, Fisiologia i Immunologia, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain; and.
authors.forename: G
authors.identifier: http://orcid.org/0000-0003-4942-2346
authors.initials: G
authors.lastname: Viscor
authors.affiliation: Departament de Biologia Cel·lular, Fisiologia i Immunologia, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain; and.
authors.forename: J R
authors.initials: JR
authors.lastname: Torrella
mesh_terms: D000532:Altitude Sickness / Q000503:physiopathology*; D000818:Animals; D008297:Male; D018482:Muscle, Skeletal / Q000033:anatomy & histology* / Q000502:physiology*; D010805:Physical Conditioning, Animal; D010807:Physical Endurance / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020127:Recovery of Function / Q000502:physiology*
keywords: aerobic exercise; eccentric exercise-induced muscle damage; intermittent hypobaric hypoxia; soleus fiber morphofunctionality