Effect of alteration of peripheral blood flow on the central circulation in man during supine cycling in different ambient temperatures

Autor: Yoshio Kuroda, Shizuo Ito, Katsumi Tsukagoshi, Y Suzuki, Teruya Amemiya
Rok vydání: 1980
Předmět:
Zdroj: European Journal of Applied Physiology and Occupational Physiology. 45:69-80
ISSN: 1439-6327
0301-5548
Popis: Whether the alteration of peripheral circulation caused by changing ambient temperature (Ta) affects central circulatory changes in man during supine cycling was investigated in four well-trained men, who exercised at two levels (117.7 or 176.6 W). Exercise metabolic rate (VO2) in cold (0 degree C or 10 degrees C) was the same as it was at 20 degrees C, whereas the cardiac output (CO; CO2 rebreathing technique) and heart rate were significantly lower (e.g.,176.6 W at 0 degree C, both p0.01). In heat (30 degrees C or 40 degrees C), the VO2 reduced with falling CO and mean arterial blood pressure from those at 20 degrees C (e.g., 176.6 W at 40 degrees C, all cases p0.01), whereas the peak post-exercise calf blood (CBFp) increased (p0.01). The VO2 and stroke volume (SV) were inversely proportional to the ratio of CBFp to CO/kg body weight (CBFp/CO) (r-0.78, p0.001). Total peripheral resistance (TPR) was related to arteriovenous oxygen difference (A-VO2 difference) (r0.78, p0.001). The TPR and A-VO2 difference decreased as Ta rose, while CBFp/CO was almost the same. As CBFp/CO had exceeded 50 and further progressed, however, the two parameters elevated until the same level as that at 0 degree C. The present results suggest that during moderately prolonged (16--60 min) supine cycling in different Ta's the central circulatory changes are mainly affected by the altered peripheral blood flow in competing between skin and muscle for blood flow.
Databáze: OpenAIRE
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