Document Detail

Endurance training under 2500-m hypoxia does not increase myoglobin content in human skeletal muscle.
MedLine Citation:
PMID:  11606019     Owner:  NLM     Status:  MEDLINE    
The present study was carried out to determine whether myoglobin (Mb) concentration ([Mb]) in human skeletal muscle is influenced by 8 weeks of endurance training under normal conditions, and under hypoxic conditions equivalent to an altitude of 2500 m. Fourteen healthy but sedentary male adults who did not participate in any regular exercise program took part in this study. They were divided into two groups according to the training regime to which they were submitted: the N group, who exercised under normobaric conditions, and the H group, who exercised under hypobaric conditions. All subjects performed an incremental cycling exercise at sea level to evaluate their maximal O2 uptake (VO2max) before and after the 8-week endurance training course period. Muscle tissue samples were obtained by needle biopsy from the vastus lateralis muscle for histochemical and biochemical analysis. Training induced an increase in VO2max in both the N and H groups (P < 0.05), although there was no significant difference in these changes between groups. The 8-week training had no effect on [Mb] in either group. Muscle fiber composition was also unaffected by the training course. In contrast, citrate synthase activity in both groups increased by [mean (SD)] 28.2 (33.3)% (N: P < 0.01) and 32.0 (18.2)% (H: P < 0.05) after training, and the number of capillaries (capillary:fiber ratio) increased by 47.7 (33.8)% (N: P < 0.01) and 32.3 (20.6)% (H: P < 0.05). There were no significant differences in these parameters between the N and H groups. These results suggest that significant improvement of aerobic potential as a result of endurance training are not accompanied by increases in [Mb] in human skeletal muscle. In addition, a lower absolute workload may not be sufficient to stimulate Mb synthesis in humans, even where endurance training is carried out under hypoxia.
K Masuda; K Okazaki; S Kuno; K Asano; H Shimojo; S Katsuta
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  European journal of applied physiology     Volume:  85     ISSN:  1439-6319     ISO Abbreviation:  Eur. J. Appl. Physiol.     Publication Date:  2001 Sep 
Date Detail:
Created Date:  2001-10-18     Completed Date:  2002-03-12     Revised Date:  2005-11-17    
Medline Journal Info:
Nlm Unique ID:  100954790     Medline TA:  Eur J Appl Physiol     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  486-90     Citation Subset:  IM    
Center for Tsukuba Advanced Research Alliance, University of Tsukuba, Tsukuba City, Ibaraki, Japan.
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MeSH Terms
Anoxia / metabolism*
Atmospheric Pressure
Capillaries / physiology
Citrate (si)-Synthase / metabolism
Muscle Fibers, Fast-Twitch / metabolism
Muscle Fibers, Slow-Twitch / metabolism
Muscle, Skeletal / blood supply,  cytology,  metabolism*
Myoglobin / metabolism*
Oxygen Consumption / physiology
Physical Endurance / physiology*
Reg. No./Substance:
0/Myoglobin; EC (si)-Synthase

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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