Summary
Six essentially hypertensive men (average resting arterial pressure of 150/97 mm Hg) and eight normotensive controls (average resting arterial pressure of 115/73 mm Hg) were tested during 1 h of dynamic leg exercise in a warm environment. The groups were well matched for age, \(\dot V_{{\text{O}}_{\text{2}} }\) max, body surface area, weight, and body fat. Environmental conditions were 38‡ C dry-bulb, 28‡ C wet-bulb; exercise intensity was approximately 40% \(\dot V_{{\text{O}}_{\text{2}} }\) max (85–90 W). There were no significant intergroup differences in core or mean skin temperatures, calculated heat exchange variables, heart, or sweat rates. Blood pressure differences between the groups were maintained (P<0.01). The hypertensive group responded with a significantly lower stroke index (P<0.01) and cardiac index (P<0.01), and a decreased slope of the rise in forearm blood flow (P<0.01) due to an higher vascular resistance (P<0.01). The combined heat load (M + R + C) presented was not sufficient to override the hypertensives' higher cutaneous vasoconstrictor tone. However, on a practical basis, the hypertensives were able to tolerate exercise in the heat as well as their normotensive counterparts.
Similar content being viewed by others
References
Allen TH, Peng MT, Chen KP, Huang TF, Chang C, Fang HS (1956) Prediction of total adiposity from skinfolds and the curvilinear relationship between external and internal adiposity. Metabolism 5: 346–352
Amery A, Julius S, Whitlock LS, Conway J (1967) Influence of hypertension on the hemodynamic response to exercise. Circulation 36: 231–237
Belding HS, Kamon E (1973) Evaporative coefficients for prediction of safe limits in prolonged exposures to work under hot conditions. Fed Proc 32: 1598–1601
Blair DA, Glover WE, Roddie IC (1961) Vasomotor responses in the human arm during leg exercise. Circ Res 9: 264–271
Brengelmann GL, McKeag M, Rowell LB (1975) Use of dew-point detection for quantitative measurement of sweating rate. J Appl Physiol 39: 498–500
Brod J, Eenel V, Hejl Z, Jirka J, Ulrych M (1962) General and regional hemodynamic pattern underlying essential hypertension. Clin Sci 23: 339–349
Brodie TG, Russell AE (1905) On the determination of the rate of blood flow through an organ. J Physiol 32: 67–69
Conway J (1963) A vascular abnormality in hypertension. Circulation 27: 520–529
Denniston JC, Maher JT, Reeves JT, Cruz JC, Cymerman A, Grover RF (1976) Measurement of cardiac output by electrical impedance at rest and during exercise. J Appl Physiol 40: 91–95
Detry JMR, Brengelmann GL, Rowell LB, Wyss C (1972) Skin and muscle components of forearm blood flow in directly heated resting man. J Appl Physiol 32: 506–511
DuBois D, DuBois EF (1916) Clinical calorimetry X. A formula to estimate the approximate surface area if height and weight be known. Arch Int Med 17: 863–871
Johnson JM, Niederberger M, Rowell LB, Eisman MM, Brengelmann GL (1973) Competition between cutaneous vasodilator and vasoconstrictor reflexes in man. J Appl Physiol 35: 798–803
Johnson JM, Rowell LB, Brengelmann GL (1974) Modification of the skin blood flow-body temperature relationship by upright exercise. J Appl Physiol 37: 880–886
Johnson JM, Rowell LB (1975) Forearm skin and muscle vascular responses to prolonged leg exercise in man. J Appl Physiol 39: 920–924
Kerslake DMcK (1972) The stress of hot environments. Cambridge University Press, Cambridge
Kubicek WG, Karnegis MJ, Patterson RB, Witsoc DA, Mattson RH (1966) Development and evaluation of an impedance cardiac output system. Aerospace Med 37: 1208–1212
Levy AM, Tabikins BS, Hanson JS (1967) Hemodynamic responses to graded treadmill exercise in young untreated labile hypertensive patients. Circulation 35: 1063–1072
Lund-Johansen P (1976) Hemodynamic trends in untreated essential hypertension. Preliminary report on a 10 year follow-up study. Acta Med Scand 602: 68–75
Lund-Johansen P (1980) Hemodynamics in essential hypertension. Clin Sci 59: 3435–3545
Miyamoto Y, Takabashi M, Tamura T, Nakamura T, Hiura T, Mikami M (1981) Continuous determination of cardiac output during exercise by the use of impedance plethysmography. Med Biol Eng Comput 19: 638–644
Mulvany MJ, Hansen PK, Aalkjaer C (1978) Direct evidence that the greater contractility of resistance vessels in spontaneously hypertensive rats is associated with a narrowed lumen, a thickened media, and an increased number of smooth cell layers. Circ Res 43: 854–864
Nishi Y, Gagge AP (1970) Mathematical model of man's heat exchange with his thermal environment. A I Ch E Symposium Series 70: 226–232
Nishi Y (1973) Vapor permeation efficiency of clothing by napthalene sublimation. Arch Sci Physiol 27: A163-A169
Pickering GW (1936) The peripheral resistance in persistent arterial hypertension. Clin Sci 2: 209–215
Roberts J (1981) Hypertension in adults 25–74 years of age, United States, 1971–1975. Vital and Health Statistics: Series II, Data from the National Health Survey, No. 221. U.S. Department of Health and Human Services
Rowell LB, Marx HJ, Bruce RA, Conn RD, Kusumi F (1966) Reductions in cardiac output, control blood volume and stroke volume with thermal stress in normal men during exercise. J Clin Invest 45: 1801–1816
Rowell LB, Wyss CR, Brengelmann GL (1973) Sustained human skin and muscle vasoconstriction with reduced baroreceptor activity. J Appl Physiol 34: 634–643
Safar ME, Weiss YA, Leverson JA, London GM, Milliez PL (1973) Hemodynamic study of 85 patients with borderline hypertension. Am J Cardiol 31: 315–319
Sannerstedt R (1969) Hemodynamic findings at rest and during exercise in mild arterial hypertension. Am J Med Sci 258: 70–79
Takeshita A, Tanaka S, Kuroiwa A, Nakamura M (1975) Reduced baroreceptor sensitivity in borderline hypertension. Circ 51: 738–742
Temmar MM, Safar ME, Leversen JA, Totamoukovo JM, Simon AC (1981) Regional blood flow in vorderline and sustained essential hypertension. Clin Sci 60: 653–658
Tsuchiya M (1972) Hemodynamic studies on hypertension. Hemodynamic characteristics in the resting supine position. Jpn Circ J 36: 267–274
Webb RC, Bohr DF (1981) Recent advances in the pathogenesis of hypertension: consideration of structural, function, and metabolic vascular abnormalities resulting in elevated arterial resistance. Am Heart J 102: 251–264
Yablonski MR, Vande Water JM, Mount BF, Laska ED, Indech RB (1980) Calibrated impedance plethysmograph. Am J Physiol 239: H283-H288
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Kenney, W.L., Kamon, E. Comparative physiological responses of normotensive and essentially hypertensive men to exercise in the heat. Europ. J. Appl. Physiol. 52, 196–201 (1984). https://doi.org/10.1007/BF00433392
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00433392