Document Detail

Calf muscle oxygen saturation and the effects of supervised exercise training for intermittent claudication.
MedLine Citation:
PMID:  22503174     Owner:  NLM     Status:  Publisher    
OBJECTIVE: The mechanisms underlying the symptomatic improvement witnessed as a result of exercise training in intermittent claudication remain unclear. There is no reproducible evidence to support increased limb blood flow resulting from neovascularization. Changes in oxygenation of active muscles as a result of blood redistribution are hypothesized but unproven. This study sought evidence of improved gastrocnemius oxygenation resulting from exercise training. METHODS: The study recruited 42 individuals with claudication. After an initial control period of exercise advice, participants undertook a 3-month supervised exercise program. Spatially resolved near-infrared spectroscopy monitored calf muscle oxygen saturation (Sto(2)) during exercise and after a period of cuff-induced ischemia. Comparison was made with 14 individuals undergoing angioplasty for calf claudication. Clinical outcomes of claudication distance and maximum walking distance were measured by treadmill assessment. RESULTS: Significant increases occurred in mean [interquartile range] claudication disease (57 [38-78] to 119 [97-142] meters; P = .01) and maximum walking distance (124 [102-147] to 241 [193-265] meters; P = .02) after supervised exercise but not after the control period. No change occurred in resting Sto(2) at any interval. Angioplasty (27% [21-34] to 19% [13-29]; P = .02) but not exercise training (26% [21-32] vs 23% [20-31]; P > .20) resulted in a reduced Sto(2) desaturation in response to submaximal exercise and an increased hyperemic hemoglobin oxygen recovery rate after ischemia (0.48 [0.39-0.55] to 0.63 [0.52-0.69] s(-1); P = .01). However supervised exercise reduced the Sto(2) recovery half-time by 17% (82 [64-101] to 68 [55-89] seconds; P = .02). CONCLUSIONS: Supervised exercise training is not associated with increased gastrocnemius muscle oxygenation during exercise or increased hyperemic hemoglobin flow after a model of ischemia. This suggests that the symptomatic improvement witnessed is not the result of increased oxygen delivery to the active muscle. The enhanced recovery after exercise training therefore reflects a combination of enhanced metabolic economy and increased oxidative capacity, suggesting that exercise training helps reverse an acquired metabolic myopathy.
Tim A Beckitt; Jude Day; Maria Morgan; Peter M Lamont
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-4-11
Journal Detail:
Title:  Journal of vascular surgery : official publication, the Society for Vascular Surgery [and] International Society for Cardiovascular Surgery, North American Chapter     Volume:  -     ISSN:  1097-6809     ISO Abbreviation:  -     Publication Date:  2012 Apr 
Date Detail:
Created Date:  2012-4-16     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8407742     Medline TA:  J Vasc Surg     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2012 Society for Vascular Surgery. Published by Mosby, Inc. All rights reserved.
Department of Vascular Surgery, Bristol Royal Infirmary, Bristol, United Kingdom.
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