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


METHODS
Using a crossover randomized design, 8 runners (mean VO2max71 ml kg-1min-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.


RESULTS
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.


CONCLUSIONS
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.
School of Applied Sciences, Edinburgh Napier University, Sighthill Campus, Sighthill Court, Edinburgh, EH11 4BN, UK. z.boukemis@napier.ac.uk.
Boukhemis
http://orcid.org/0000-0002-5622-9846
B
Boukelia
Department of Sport, Health and Exercise Science, University of Hull, Cottingham Road, Kingston-upon-Hull, UK.
M C
MC
Fogarty
Institute of Clinical Exercise and Health Science, University of the West of Scotland, Paisley, UK.
R C R
RC
Davison
School of Applied Sciences, Edinburgh Napier University, Sighthill Campus, Sighthill Court, Edinburgh, EH11 4BN, UK.
G D
GD
Florida-James
D000328:Adult; D056352:Athletes; D015415:Biomarkers / Q000097:blood; D058639:Cold-Shock Response; D006801:Humans; D008168:Lung / Q000166:cytology / Q000276:immunology; D008297:Male; D017440:Photoperiod; D011897:Random Allocation; D012420:Running / Q000502:physiology*; D014598:Uteroglobin / Q000097:blood*
D015415:Biomarkers; D014598:Uteroglobin
CC16; Diurnal variation; Immunological markers