Open AccessCutaneous vascular reflexes during exercise in the heat
Author(s) -
Anurag Tripathi,
Gary W. Mack,
E. R. Nadel
Publication year - 1990
Publication title -
medicine and science in sports and exercise
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.703
H-Index - 224
eISSN - 1530-0315
pISSN - 0195-9131
DOI - 10.1249/00005768-199012000-00011
Subject(s) - medicine , hypovolemia , cardiac output , stroke volume , blood pressure , baroreceptor , heart rate , cardiology , venous return curve , central venous pressure , blood volume , shock (circulatory) , forearm , reflex , anesthesia , hemodynamics , surgery
Eight relatively fit men performed cycle ergometer exercise (50% VO2max) for 30 min at 35 degrees C, less than 40% rh. To determine the importance of changes in cardiac filling pressure on the cutaneous vascular responses during exercise, we compared data from eight control (normovolemic) and four hypovolemic (19.5% decrease in plasma volume (PV) induced by diuretics) experiments. Cardiac output was maintained at 13.9 +/- 0.8 l.min-1 during steady state exercise in the two conditions. However, heart rate was higher (P less than 0.05) and stroke volume (SV) was slightly, although not statistically lower during hypovolemic exercise. Forearm venous compliance (FVC) was significantly lower during hypovolemic exercise than during control exercise (P less than 0.05). The increases in forearm blood flow and arterial blood pressure during exercise were not affected significantly by hypovolemia. FVC and SV in both conditions were linearly related to changes in central venous pressure during exercise (r2 = 0.88 and 0.78, respectively). Since changes in arterial pressure during exercise were not correlated with the observed arteriomotor and venomotor responses, we concluded that low pressure baroreceptors may have induced peripheral vascular reflexes, which act to maintain cardiac output during exercise in the heat.