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Wilderness Environ Med. 2017 Sep;28(3):197-206. doi: 10.1016/j.wem.2017.05.002. Epub 2017 Jul 22.

Blood Hemostatic Changes During an Ultraendurance Road Cycling Event in a Hot Environment.

Author information

1
Department of Military & Emergency Medicine, Uniformed Services University of Health Sciences, Bethesda, MD (Drs Kupchak and Deuster, Mr Kazman). Electronic address: brian.kupchak@usuhs.edu.
2
Department of Military & Emergency Medicine, Uniformed Services University of Health Sciences, Bethesda, MD (Drs Kupchak and Deuster, Mr Kazman).
3
Applied Physiology Laboratory, Department of Kinesiology, Health Promotion and Recreation, University of North Texas, Denton, TX (Dr Vingren and Ms. Levitt).
4
Human Performance Laboratory, Department of Kinesiology, University of Connecticut, Storrs, CT (Drs Lee and Armstrong).
5
Department of Kinesiology, Midwestern State University, Wichita Falls, TX (Dr Williamson).

Abstract

OBJECTIVE:

This study aims to examine blood hemostatic responses to completing a 164-km road cycling event in a hot environment.

METHODS:

Thirty-seven subjects (28 men and 9 women; 51.8±9.5 [mean±SD] y) completed the ride in 6.6±1.1 hours. Anthropometrics (height, body mass [taken also during morning of the ride], percent body fat [%]) were collected the day before the ride. Blood samples were collected on the morning of the ride (PRE) and immediately after (IP) the subject completed the ride. Concentrations of platelet, platelet activation, coagulation, and fibrinolytic markers (platelet factor 4, β-thromboglobulin, von Willebrand factor antigen, thrombin-antithrombin complex, thrombomodulin, and D-Dimer) were measured. Associations between changes from PRE- to IP-ride were examined as a function of event completion time and subject characteristics (demographics and anthropometrics).

RESULTS:

All blood hemostatic markers increased significantly (P < .001) from PRE to IP. After controlling for PRE values, finishing time was negatively correlated with platelet factor 4 (r = 0.40; P = .017), while percent body fat (%BF) was negatively correlated with thrombin-antithrombin complex (r = -0.35; P = .038) and to thrombomodulin (r = -0.36; P = .036). In addition, male subjects had greater concentrations of thrombin-antithrombin complex (d = 0.63; P < .05) and natural logarithm thrombomodulin (d = 6.42; P < .05) than female subjects.

CONCLUSION:

Completing the 164-km road cycling event in hot conditions resulted in increased concentrations of platelet, platelet activation, coagulation, and fibrinolytic markers in both men and women. Although platelet activation and coagulation occurred, the fibrinolytic system markers also increased, which appears to balance blood hemostasis and may prevent clot formation during exercise in a hot environment.

KEYWORDS:

coagulation; cycling; fibrinolysis; heat stress; platelet activation

PMID:
28739377
DOI:
10.1016/j.wem.2017.05.002
[Indexed for MEDLINE]

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