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Diurnal physiological and immunological responses to a 10-km run in highly trained athletes in an environmentally controlled condition of 6 °C

Boukelia, Boukhemis; Fogarty, M C; Davison, R C R; Florida-James, G D


Boukhemis Boukelia

M C Fogarty

R C R Davison



The Clara cell protein CC16, secreted from Clara cells in the lung, is discussed as a potential biomarker for toxic effects on the airways. An increased concentration of CC16 in serum may be caused by increased permeability of the lungs. To investigate the changes in P-CC16 in response to an intense exercise bout performed at different times of day (9 am and 4 pm) of highly trained individuals.


Using a crossover randomized design, 8 runners (mean VO2max 71 ml kg−1 min−1, SD 6) performed a 10-km time trial run, at 9 am and 4 pm, in an environmental chamber set at 6 °C. Lung function tests and blood sampling occurred at baseline, immediately post and 1 h post time trial.


Diurnal differences (P < 0.05) were found for blood neutrophil and lymphocyte counts; with higher values at 4 pm. P-CC16 was higher at the pre- and post-trial time point at 9 am compared to 4 pm. Lung function was not different between or within trials.


Morning trial in cold condition caused more physiological strain compared to the same trial in the evening. However, this extra stress caused by zeitgebers could be a useful strategy for athletes, coaches, and general population to improve their running performance and protect their health in cold conditions in the long-term plan.


Boukelia, B., Fogarty, M. C., Davison, R. C. R., & Florida-James, G. D. (2016). Diurnal physiological and immunological responses to a 10-km run in highly trained athletes in an environmentally controlled condition of 6 °C. European Journal of Applied Physiology, 117(1), 1-6.

Journal Article Type Article
Acceptance Date Oct 13, 2016
Online Publication Date Nov 9, 2016
Publication Date Nov 9, 2016
Deposit Date Nov 15, 2016
Publicly Available Date Nov 15, 2016
Journal European Journal of Applied Physiology
Print ISSN 1439-6319
Electronic ISSN 1439-6327
Publisher Springer
Peer Reviewed Peer Reviewed
Volume 117
Issue 1
Pages 1-6
Keywords Immunological markers, CC16, Diurnal variation,
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