Document Detail

Circadian effects on the acute responses of salivary cortisol and IgA in well trained swimmers.
MedLine Citation:
PMID:  12145115     Owner:  NLM     Status:  MEDLINE    
OBJECTIVE: To examine whether time of day significantly affects salivary cortisol and IgA levels before and after submaximal swimming. METHODS: Fourteen male competitive swimmers (mean (SD) age 18 (3.2) years) volunteered to participate in the study. In a fully randomised, cross over design, each subject performed 5 x 400 m front crawl at 85 (1.2)% of their seasonal best time (277 (16) seconds), with one minute rest between each 400 m, at 0600 and 1800 hours on two separate days. Timed, unstimulated saliva samples were collected before and after exercise. Saliva samples were analysed for cortisol and IgA by radioimmunoassay and single radial immunodiffusion respectively. RESULTS: Significant time of day effects (am and pm respectively) were observed in IgA concentration (0.396 (0.179) v 0.322 (0.105) mg/ml, p<0.05), IgA secretory rate (0.109 (0.081) v 0.144 (0.083) mg/min, p<0.01), and saliva flow rate (0.31 (0.23) v 0.46 (0.22) ml/min, p<0.001) before exercise (all values mean (SD)). Differences in cortisol levels before exercise (1.09 (0.56) v 0.67 (0.94) microg/dl) approached significance (p = 0.059). The exercise protocol did not significantly affect IgA concentration and secretory rate (p>0.05) but, in comparison with values before exercise, caused significant alterations in cortisol (p<0.01) and saliva flow rate (p<0.01). There was no significant interaction effect of time of day by exercise on any salivary variables measured (p>0.05). However, most of the values of the salivary variables before exercise were significantly inversely related to their exercise induced response (p<0.05). CONCLUSION: These results suggest a significant circadian variation in the variables measured before exercise, without showing a significant effect on their acute responses to exercise.
L Dimitriou; N C C Sharp; M Doherty
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Publication Detail:
Type:  Clinical Trial; Journal Article; Randomized Controlled Trial    
Journal Detail:
Title:  British journal of sports medicine     Volume:  36     ISSN:  0306-3674     ISO Abbreviation:  Br J Sports Med     Publication Date:  2002 Aug 
Date Detail:
Created Date:  2002-07-29     Completed Date:  2002-11-08     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  0432520     Medline TA:  Br J Sports Med     Country:  England    
Other Details:
Languages:  eng     Pagination:  260-4     Citation Subset:  IM    
Department of Sport Sciences, Brunel University, Osterley Campus, Borough Road Isleworth, Middlesex TW7 5DU, UK.
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MeSH Terms
Analysis of Variance
Circadian Rhythm*
Cross-Over Studies
Hydrocortisone / analysis*
Immunoglobulin A / analysis*
Saliva / chemistry*
Swimming / physiology*
Reg. No./Substance:
0/Immunoglobulin A; 50-23-7/Hydrocortisone
Comment In:
Br J Sports Med. 2003 Apr;37(2):187   [PMID:  12663367 ]

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