Document Detail

Is the rate of whole-body nitrogen elimination influenced by exercise?
MedLine Citation:
PMID:  22400450     Owner:  NLM     Status:  In-Process    
BACKGROUND: Because it has earlier been shown that exercise 24 or two hours pre-dive may suppress the appearance of venous gas bubbles (VGB) in connection with the dive, we studied whether exercise before or during N2 elimination would influence the rate of the latter. Nitrogen elimination was recorded in eight volunteers breathing a normoxic O2+argon mixture for two hours. The N2 washout was preceded two (Condition A) or 24 hours (Condition B) earlier, by one hour of exercise at 85% VO2max (two hours of exercise interspersed with two hours of rest). In separate experiments, exercise at -40% of VO2max was performed throughout the two-hour washout (Condition C), and control experiments (Condition D) with denitrogenation without exercise were also performed.
RESULTS: There were no significant differences among conditions for the total N2 eliminated (904 +/- 196 mL). The half-times of N2 washout for A (35.2 +/- 10.8 minutes) and B (31.9 +/- 8.6 minutes) did not differ from control washouts. The rate of washout in C increased 14% compared to D (half-time: 30.4 +/- 7.6 vs. 34.5 +/- 7.8 minutes, p = 0.002), and correlated with cardiac output.
CONCLUSION: Exercise 24 or two hours pre-N2 washout did not affect it, suggesting that the decreased VGB scores noted by others in dives preceded by conditions similar to A and B are not due to changes in nitrogen exchange but rather to factors related to bubble formation and/or appearance. That N2 elimination is enhanced by concomitant exercise makes physiological sense but does not necessarily explain the observation by others of a reduced risk of decompression sickness with exercise before diving.
D R Pendergast; C Senf; C E G Lundgren
Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Undersea & hyperbaric medicine : journal of the Undersea and Hyperbaric Medical Society, Inc     Volume:  39     ISSN:  1066-2936     ISO Abbreviation:  Undersea Hyperb Med     Publication Date:    2012 Jan-Feb
Date Detail:
Created Date:  2012-03-09     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9312954     Medline TA:  Undersea Hyperb Med     Country:  United States    
Other Details:
Languages:  eng     Pagination:  595-604     Citation Subset:  IM; S    
Center for Research and Education in Special Environments, Department of Physiology and Biophysics, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York, USA.
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