PMID- 11581327
OWN - NLM
STAT- MEDLINE
DCOM- 20011207
LR  - 20220216
IS  - 0022-0949 (Print)
IS  - 0022-0949 (Linking)
VI  - 204
IP  - Pt 18
DP  - 2001 Sep
TI  - Muscle tissue adaptations to hypoxia.
PG  - 3133-9
AB  - This review reports on the effects of hypoxia on human skeletal muscle tissue. It 
      was hypothesized in early reports that chronic hypoxia, as the main physiological 
      stress during exposure to altitude, per se might positively affect muscle 
      oxidative capacity and capillarity. However, it is now established that sustained 
      exposure to severe hypoxia has detrimental effects on muscle structure. 
      Short-term effects on skeletal muscle structure can readily be observed after 2 
      months of acute exposure of lowlanders to severe hypoxia, e.g. during typical 
      mountaineering expeditions to the Himalayas. The full range of phenotypic 
      malleability of muscle tissue is demonstrated in people living permanently at 
      high altitude (e.g. at La Paz, 3600-4000 m). In addition, there is some evidence 
      for genetic adaptations to hypoxia in high-altitude populations such as Tibetans 
      and Quechuas, who have been exposed to altitudes in excess of 3500 m for 
      thousands of generations. The hallmark of muscle adaptation to hypoxia in all 
      these cases is a decrease in muscle oxidative capacity concomitant with a 
      decrease in aerobic work capacity. It is thought that local tissue hypoxia is an 
      important adaptive stress for muscle tissue in exercise training, so these 
      results seem contra-intuitive. Studies have therefore been conducted in which 
      subjects were exposed to hypoxia only during exercise sessions. In this 
      situation, the potentially negative effects of permanent hypoxic exposure and 
      other confounding variables related to exposure to high altitude could be 
      avoided. Training in hypoxia results, at the molecular level, in an upregulation 
      of the regulatory subunit of hypoxia-inducible factor-1 (HIF-1). Possibly as a 
      consequence of this upregulation of HIF-1, the levels mRNAs for myoglobin, for 
      vascular endothelial growth factor and for glycolytic enzymes, such as 
      phosphofructokinase, together with mitochondrial and capillary densities, 
      increased in a hypoxia-dependent manner. Functional analyses revealed positive 
      effects on V(O(2)max) (when measured at altitude) on maximal power output and on 
      lean body mass. In addition to the positive effects of hypoxia training on 
      athletic performance, there is some recent indication that hypoxia training has a 
      positive effect on the risk factors for cardiovascular disease.
FAU - Hoppeler, H
AU  - Hoppeler H
AD  - Department of Anatomy, University of Bern, Buhlstrasse 26, CH-3000 Bern 9, 
      Switzerland. hoppeler@ana.unibe.ch
FAU - Vogt, M
AU  - Vogt M
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Review
PL  - England
TA  - J Exp Biol
JT  - The Journal of experimental biology
JID - 0243705
RN  - 0 (DNA-Binding Proteins)
RN  - 0 (HIF1A protein, human)
RN  - 0 (Hypoxia-Inducible Factor 1)
RN  - 0 (Hypoxia-Inducible Factor 1, alpha Subunit)
RN  - 0 (Nuclear Proteins)
RN  - 0 (Transcription Factors)
SB  - IM
MH  - Acclimatization
MH  - *Adaptation, Physiological
MH  - *Altitude
MH  - Bolivia
MH  - DNA-Binding Proteins/genetics
MH  - Exercise/physiology
MH  - Humans
MH  - Hypoxia/genetics/pathology/*physiopathology
MH  - Hypoxia-Inducible Factor 1
MH  - Hypoxia-Inducible Factor 1, alpha Subunit
MH  - Indians, South American
MH  - Mountaineering/physiology
MH  - Muscle, Skeletal/pathology/*physiopathology
MH  - Nuclear Proteins/genetics
MH  - Tibet
MH  - *Transcription Factors
RF  - 43
EDAT- 2001/10/03 10:00
MHDA- 2002/01/05 10:01
CRDT- 2001/10/03 10:00
PHST- 2001/10/03 10:00 [pubmed]
PHST- 2002/01/05 10:01 [medline]
PHST- 2001/10/03 10:00 [entrez]
AID - 10.1242/jeb.204.18.3133 [doi]
PST - ppublish
SO  - J Exp Biol. 2001 Sep;204(Pt 18):3133-9. doi: 10.1242/jeb.204.18.3133.