Effects of sildenafil on the human response to acute hypoxia and exercise

We examined the effects of the 5-phosphodiesterase (5-PDE) inhibitor sildenafil on pulmonary arterial pressure and some oxygen transport and cardiopulmonary parameters in humans during exposure to hypobaric hypoxia at rest and after exercise. In a double-blind study, 100 mg sildenafil or placebo was administered orally to 14 healthy volunteers 45 min before exposure to 5,000 m of simulated altitude. Arterial oxygen saturation (SaO2), heart rate (HR), tidal volume (VT), respiratory rate (RR), left ventricular ejection fraction (EF), and pulmonary arterial pressure (PAP) were measured first at rest in normoxia, at rest and immediately after exercise during hypoxia, and after exercise in normoxia. The increase in systolic PAP produced by hypoxia was significantly decreased by sildenafil at rest from 40.9 +/- 2.6 to 34.9 +/- 3.0 mmHg (-14.8%; p = 0.0046); after exercise, from 49.0 +/- 3.9 to 42.9 +/- 2.6 mmHg (-12.6%; p = 0.003). No significant changes were found in normoxia either at rest or after exercise. Measurements of the effect of sildenafil on exercise capacity during hypoxia did not provide conclusive data: a slight increase in SaO2 was observed with exercise during hypoxia, and sildenafil did not cause significant changes in ventilatory parameters under any condition. Sildenafil diminishes the pulmonary hypertension induced by acute exposure to hypobaric hypoxia at rest and after exercise. Further studies are needed to determine the benefit from this treatment and to further understand the effects of sildenafil on exercise capacity at altitude.     

Circulatory response to acute hypobaric hypoxia in conscious dogs.

Hemodynamics were studied in seven conscious dogs during acute hypobaric stress at 14,000 ft simulated altitude. Silastic catheters were chronically implanted in the pulmonary artery, left atrium, and aorta. Pulmonary and central aortic pressures, cardiac output, and pulmonary blood volume were determined under conditions of normoxia and acute hypoxia in a hypobaric chamber maintained at 446 mm Hg pressure (14,000 ft). Altitude resulted in significant increases in heart rate, cardiac output, pulmonary blood volume, and pulmonary artery pressure. Left atrial pressure and calculated systemic vascular resistance decreased during hypobaric hypoxia while stroke volume, stroke work index, arterial pressure and pulmonary vascular resistance remained unchanged. Arterial blood PO2 decreased markedly at altitude, and all animals hyperventilated with resultant systemic hypocarbic alkalosis. The combination of elevated pulmonary arterial pressure and increased pulmonary blood volume may by an etiologic factor in the development of high-altitude pulmonary edema.     

Sustained acclimatization in Chilean mine workers subjected to chronic intermittent hypoxia

Farias, Jorge G., Jorge Osorio, Gustavo Soto, Julio Brito, Patricia Siques, and Juan G. Reyes. Sustained acclimatization in Chilean mine workers subjected to chronic intermittent hypoxia. High Alt. Med. Biol. 7:302-306, 2006--We wanted to know if sea-level mine workers exposed previously to chronic intermittent hypoxia reached a steady acclimatization at 36 months under hypobaric hypoxia. An intermittently exposed group of mine workers (IE, n = 25) were subjected to submaximal exercise (100 W) at 4500 m. Their systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), and hemoglobin oxygen saturation (HbSatO(2)) were monitored. Two comparison groups of unacclimatized sea-level workers (n = 17) were studied. A nonexposed group (NE) performed 5 min of submaximal exercise at sea level. Some kind of exercise was performed both by an acutely exposed group (AE) and IE group at 4500 m. No statistical differences were found for HR, SBP, and DBP (p > 0.05) during exercise between IE and AE groups. Resting HbSatO(2) of IE (87 +/- 6%) was lower than NE (97 +/- 3%) (p < 0.05), but was higher than AE (82 +/- 4%) (p < 0.05). In the exercise condition, HbSatO(2) of IE (85 +/- 5%) was lower than NE (95 +/- 3%) (p < 0.05), but was higher than AE (76 +/- 2%) (p < 0.05). These responses were maintained through the 6 months of the study period. Thus, mine workers subjected to intermittent hypobaric condition for 3 years showed a good degree of acclimatization that was maintained through time.     

Intermittent hypobaric hypoxia induces altitude acclimation and improves the lactate threshold

The physiological responses to short-term intermittent exposure to hypoxia in a hypobaric chamber were evaluated. The exposure to hypoxia was compatible with normal daily activity. The ability of the hypoxia program to induce hematological and ventilatory adaptations leading to altitude acclimation and to improve physical performance capacity was tested. Six members of a high-altitude expedition were exposed to intermittent hypoxia and low-intensity exercise (in cycle-ergometer) in the INEFC-UB hypobaric chamber over 17 d, 3-5 h x d(-1), at simulated altitude of 4,000 m to 5,500 m. Following this hypoxia exposure program, significant increases were found in packed cell volume (41 to 44.6%; p<0.05), red blood cells count (4.607 to 4.968 10(6) cells x microL(-1); p<0.05), and hemoglobin concentration (14.8 to 16.4 g x dL(-1); p<0.05), thus implying an increase in the blood oxygen transport capacity. Significant differences in exercise blood lactate kinetics and heart rate were also observed. The lactate vs. exercise load curve shifted to the right and heart rate decreased, thus indicating an improvement of aerobic endurance. These results were associated with a significant increase in the ventilatory anaerobic threshold (p<0.05). Significant increases (p<0.05) in pulmonary ventilation, tidal volume, respiratory frequency, O2 uptake, CO2 output and ventilatory equivalents to oxygen (VE/Vo2) and carbon dioxide (VE/co2) were observed at the ventilatory threshold and within the transitional zone of the curves. We conclude that short-term intermittent exposure to moderate hypoxia, in combination with low-intensity exercise in a hypobaric chamber, is sufficient to improve aerobic capacity and to induce altitude acclimation.     

Comparison of exercise responses of males and females during acute exposure to hypobaria

Seventeen male and 20 female college students were tested on a bicycle ergometer in a hypobaric chamber to determine whether both sexes had similar submax and max exercise responses to acute hypoxia. Initial testing was at a terrestrial altitude of 1576 m, to which the subjects were acclimated; subsequent tests were at simulated altitudes of 2743 m and 3962 m. Analysis of covariance showed that inspired V was the only variable during submaximal work (50% max) to exhibit a significant difference in altitude response between males and females; women had a smaller increase than men. During max work, V and O2 pulse increased less in women. At 2743 m, max VO2 decreased more in females whereas, at 3962 m, no difference was noted. It was concluded that during both submaximal and maximal work with acute altitude exposure, women would demonstrate smaller relative increases in ventilation than would men.     

Effect of body position on the afterload response during sustained exercise.

Hemodynamic and cardiovascular responses were studied in 80 males (age: 30 +/- 2 years) at rest, and during separate three minute trials of upright and supine isometric deadlift exercise at 30% of maximum voluntary contraction (MVC). MVC did not differ significantly between supine and upright deadlift exercise. In comparison to values at rest, both forms of isometric exercise resulted in significant increases (p less than 0.05) in heart rate, systolic blood pressure, diastolic blood pressure, mean arterial blood pressure, oxygen uptake, oxygen pulse and double product. In the upright exercise, the values obtained for all of the physiological variables were found to be significantly higher (p less than 0.05) than in the supine exercise. These findings indicate that the upright isometric deadlift produces a higher after-load than the supine maneuver, and that this response may be a good indicator of cardiovascular functioning.     

Effects of sildenafil on exercise capacity in hypoxic normal subjects

The phosphodiesterase-5 inhibitor sildenafil has been reported to improve hypoxic exercise capacity, but the mechanisms accounting for this observation remain incompletely understood. Sixteen healthy subjects were included in a randomized, double-blind, placebo-controlled, cross-over study on the effects of 50-mg sildenafil on echocardiographic indexes of the pulmonary circulation and on cardiopulmonary cycle exercise in normoxia, in acute normobaric hypoxia (fraction of inspired O2, 0.1), and then again after 2 weeks of acclimatization at 5000 m on Mount Chimborazo (Ecuador). In normoxia, sildenafil had no effect on maximum VO2 or O2 saturation. In acute hypoxia, sildenafil increased maximum VO2 from 27 +/- 5 to 32 +/- 6 mL/min/kg and O2 saturation from 62% +/- 6% to 68% +/- 9%. In chronic hypoxia, sildenafil did not affect maximum VO2 or O2 saturation. Resting mean pulmonary artery pressure increased from 16 +/- 3 mmHg in normoxia to 28 +/- 5 mmHg in normobaric hypoxia and 32 +/- 6 mmHg in hypobaric hypoxia. Sildenafil decreased pulmonary vascular resistance by 30% to 50% in these different conditions. We conclude that sildenafil increases exercise capacity in acute normobaric hypoxia and that this is explained by improved arterial oxygenation, rather than by a decrease in right ventricular afterload.     

Baroreflex responsiveness during hypobaric hypoxia

Baroreflex responses to graded neck suction during held expiration were studied in five healthy females at sea level and at a simulated altitude of 4,572 m (15,000 ft), with and without oxygen administration. An apparent resetting of the baroreflex was observed during hypobaric hypoxia, but this effect was abolished by oxygen administration. Held expiration alone induced a pulse prolongation in all experimental conditions, however this bradycardiac response was smaller during hypobaric hypoxia than during the two normoxic conditions. When the bradycardic responses of held expiration were subtracted, the baroreflex responses to neck suction were equal in all experimental situations. Similarly, the baroreflex was unaffected by hypobaric hypoxia when the R-R interval prolongations were expressed in percentage of the R-R intervals immediately prior to the neck suction. These data indicate that reduced ambient pressure per se has no influence on the carotid baroreflex control of heart rate.     

Effects of mountaineering training at high altitude (4,350 m) on physical work performance of women

BACKGROUND: Little is known about work performance of women in hypobaric hypoxia. Moreover, whether native women of moderate altitude (2,000-2,100 m) differ from their lowland counterparts in their ability to adjust to hypobaric hypoxia is also not known. Hence, physiological alterations on work performance due to mountaineering training with altitude adaptation was evaluated in two groups of women and compared to the differences in the responses of the native women of moderate altitudes (Highlanders-HL) with those of the plains (Lowlanders-LL). METHODS: Pre-training tests were conducted at 2,100 m, then during sojourn to 4,350 m and re-tested again after return to 2,100 m. Physical work performance was assessed following standard step-test-exercise on a 30 cm stool with 24 cycles x min(-1) for 5 min. Heart rate, BP, ventilation, oxygen consumption and oxygen saturation were monitored at rest and during exercise followed by 5 min recovery in all three situations. RESULTS: During initial assessment, HL showed higher cardiovascular efficiency with faster recovery of exercise heart rate. Both groups showed significant improvement in physical performance due to mountaineering training at high altitude (HA). The difference in performance between two groups narrowed down at 4,350 m and further reduced during re-test with maintenance of initial superiority of the HL. CONCLUSIONS: a) Native women of moderate altitude (HL) are more fit compared with their plains counterparts (LL); b) All women achieved marked improvement in cardiovascular and respiratory efficiency as well as the step-test score due to intense mountaineering training at HA, and the rate of improvement in physical performance was higher in LL; c) Further, induction by trekking under progressive hypoxia coupled with rigorous mountaineering activity at HA merits in understanding better acclimatization and improved physical performance.     

Short hypobaric hypoxia and breathing pattern: effect of positive end expiratory pressure.

The ventilatory effects of a 5-cm H2O positive end expiratory pressure (PEEP) and its influence on the breathing pattern during short hypoxic exposure both at rest and during physical exercise were studied. There were 22 healthy subjects who were submitted to normoxia and to 4-h of hypoxia in a hypobaric chamber (4500 m, PB = 589 hPa) both at rest and during an 8-min cycle ergometer exercise (100 W) without and with a 5 cm H2O PEEP. The results show that hypoxia compared with normoxia induces increases in tidal volume (VT) (+28.5%, p < 0.05 at rest; and +19.4%, p < 0.01 at 100 W) and in respiratory frequency (f) at 100 W (p < 0.05), and significant decreases in inspiratory (tI) (p < 0.05 at rest and at 100 W), and expiratory (tE) durations (p < 0.05 at 100 W). However, the breathing pattern expressed as duty cycle (tI/tt) is unchanged, whereas an increased mean inspiratory flow (VT/tI) is observed (p < 0.01 at rest and at 100 W). This study also demonstrates that PEEP during a 4-h hypobaric hypoxia significantly increases VT (+22.2% p < 0.01 at rest, +8.9% p < 0.05 at 100 W), tI, and tE at rest (p < 0.05), but not during exercise and tends to decrease f (p = 0.06 at rest and at 100 W). However, PEEP does not alter the breathing pattern in hypoxia since VT/tI and tI/tt are unchanged. Heart rate and arterial O2 saturation are also unaffected by PEEP. In conclusion, this study shows that a 4-h hypoxia modifies ventilatory parameters and mean inspiratory flow (VT/tI) at rest and during exercise (100 W), whereas a 5-cm H2O PEEP does not alter the breathing pattern despite changes in ventilatory parameters are observed.     

Chemoreflex and metaboreflex responses to static hypoxic exercise in aging humans

PURPOSE: We tested the hypothesis that aging decreases the contribution of metaboreceptors to sympathetic responses during exercise in hypoxia. METHODS: We recorded sympathetic nerve traffic to muscle circulation (MSNA), heart rate (HR), blood pressure (BP), minute ventilation (VE), and blood lactate (BL) in 12 older (55 +/- 10 yr) and 12 younger (22 +/- 2 yr) normal subjects during three randomized interventions: isocapnic hypoxia (chemoreflex activation), isometric handgrip exercise (HG) in normoxia (metaboreflex activation), and HG during isocapnic hypoxia (concomitant metaboreflex and chemoreflex activation). All interventions were followed by a forearm circulatory arrest period to allow metaboreflex activation in the absence of exercise and chemoreflex activation. RESULTS: Older subjects had higher resting MSNA (38 +/- 12 vs 23 +/- 9 bursts per minute; P < 0.01) and BP (P < 0.001). Heart rate, minute ventilation, and blood lactate did not differ (all P > 0.5). MSNA responses to HG in normoxia (P < 0.05) and in hypoxia (P < 0.05) were smaller in the older subjects, but were similar during hypoxia alone. The increase in HR was smaller in the older subjects for all interventions (all P < 0.05). In contrast, the increase in systolic and diastolic BP, VE, and BL were similar in both groups (P > 0.05). During the local circulatory arrest, MSNA and BP remained elevated in both groups after HG in normoxia (P < 0.01) and in hypoxia (P < 0.01), but MSNA changes were smaller in the older subjects (P < 0.05). CONCLUSION: Aging reduces sympathetic reactivity to isometric handgrip, but does not prevent the metaboreceptors to remain the main determinant of sympathetic activation during exercise in hypoxia.     

Time course of cardiovascular and hematological responses in rats exposed to chronic intermittent hypobaric hypoxia (4600 m)

The aim of this study was to evaluate the effects of two periods of intermittent exposure to hypoxia (428 torr) in rats over 12 months. The conditions of CIH4x4 (4 days in hypoxia, 4 days in normoxia, n = 50) and CIH2x2 (2 days in hypoxia, 2 days in normoxia, n = 50) were selected for simulating in this animal model the chronic-intermittent exposure to high altitudes experienced by Andean miners. We assessed mortality, weight, hematological parameters, and time course of resting heart rate and systolic blood pressure. In general, mortality increased during the first month, with a tendency to stabilize during exposure; it was associated with lower weights and with higher hematocrit levels, making these possible predictor factors. Intermittence produced an increase in hematocrit and hemoglobin concentrations as previously seen in most hypoxic models, compared with normoxia (NX, n = 30), but attained lower levels compared with chronic hypoxia (CH, n = 28). CIH4x4 and CIH2x2 had similar sustained elevations of systolic blood pressure (171 +/- 3 and 174 +/- 2 mmHg, respectively) versus the basal level (163 +/- 3; 163 +/- 3 mmHg), whereas CH did not. Heart rate suffered an equally sustained decrease in all exposed groups (343 +/- 14 beats/min). Exposure to chronic-intermittent hypoxia led to a mild polycythemia and to a decrease in heart rate. The effects of hypoxia were already evident during the first month of exposure and attained a more pronounced expression and stabilization during the third month.     

Effects of exercise and weight loss on blood pressure during daily life

PURPOSE: The objective of this study was to investigate the effects of exercise training and weight loss on blood pressure (BP) associated with physical activity and emotional stress during daily life. METHODS: One hundred twelve participants with unmedicated high normal or stage 1 to stage 2 hypertension were randomized to one of three conditions: a combined exercise and behavioral weight management group (WM), an exercise-only group (EX), or a wait list control group (CON). BP was assessed in the clinic and during 15 h of daytime ambulatory BP monitoring at baseline and after 6 months of treatment. RESULTS: Increased levels of physical activity and emotional distress measured during daily life were associated with increases in systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), and rate pressure product (RPP). After treatment, the WM group had significantly lower DBP, HR, and RPP responses during both high and low levels of physical activity and emotional distress compared with the CON group. The EX group had similar BP levels as the WM group, although the EX group had significantly lower BP than the CON group during low but not high levels of physical activity and emotional distress. CONCLUSION: These findings indicate that exercise, especially when combined with weight loss, reduces BP levels at rest and in situations that typically elevate BP such as intense physical activity and emotional distress.     

Blood pressure behaviour during physical activity

Aerobic exercise is currently being recommended in addition to pharmacological therapy for lowering blood pressure levels in hypertensive patients, i.e. in subjects whose resting blood pressure levels exceed 145/90 mm Hg. On the other hand competitive sports are generally contraindicated in hypertensives, who are thought to be at increased risk of morbidity or mortality from their blood pressure levels. The present knowledge of blood pressure behaviour during isotonic physical activity is almost wholly based on the results obtained by means of the ergometric tests. Several maximal and submaximal exercise protocols have been introduced, but none has proved to be superior for diagnostic purposes. There is general agreement that the systolic blood pressure increase determined by isotonic exercise usually ranges from 50 to 70 mm Hg in both normotensive or hypertensive subjects. Diastolic blood pressure shows only minor changes in the normotensives, while in the hypertensives it tends to substantially increase because of their inability to adequately reduce their peripheral resistance. This mechanism may also explain the delay shown by the hypertensives in reaching pre-exercise blood pressure values during the recovery. On average diastolic blood pressure increases to a greater extent during bicycle ergometry than during treadmill, while no differences in exertional systolic blood pressure have been observed between the 2 tests. The results of several studies indicate that the blood pressure response to isotonic exercise is a marker for detection of hypertension earlier in the course of the disease, while resting blood pressure is still normal. According to some authors it is also of value in predicting future hypertension in individuals with borderline pressure levels. There are no conclusive data on the effect of training on blood pressure response to exercise. The majority of the published studies report small exertional pressure reductions after conditioning, which would merely reflect the reduction in resting blood pressure. Vasodilation greatly influences the exercise-induced rise in blood pressure; in fact the exertional pressor increase is blunted when the test is preceded by an adequate warm-up session. Isometric effort is thought to be contraindicated in hypertensive subjects, as it causes a pronounced increase not only of systolic but also of diastolic pressure. Mean blood pressure is, however, increased to the same extent by isotonic and isometric exercise, even though minor discrepancies have been reported by some authors.(ABSTRACT TRUNCATED AT 400 WORDS)     

Fluid-regulatory hormone responses during cycling exercise in acute hypobaric hypoxia

PURPOSE: This study was designed to describe the responses of fluid-regulating hormones during exercise in acute hypobaric hypoxia and to test the hypothesis that they would be dependent on the relative intensity of exercise rather than the absolute workload. METHODS: Thirteen men cycled for 60 min on four occasions in the same individual hydration status: in normoxia at 55% and 75% of normoxia maximal aerobic power (N55 and N75, respectively), in hypoxia (PB = 594 hPa) at the same absolute workload and at the same relative intensity as N55 (H75 and H55, respectively). VO2, heart rate, and rectal and mean skin temperatures were recorded during exercise. The total water loss was measured by the difference in nude body mass adjusted for metabolic losses. Venous blood samples were drawn before and 15, 30, 45, and 60 min after the beginning of exercise to measure variations in plasma volume, osmolality, and concentrations in arginine vasopressin (AVP), atrial natriuretic factor (ANF), plasma renin activity (ARP), aldosterone (Aldo), and noradrenaline (NA). RESULTS: During N55 and H55, AVP, Aldo and ARP did not change, whereas ANF increased slightly. Increases in AVP, Aldo, ARP, and NA were greater during N75 than during H75, whereas the increase in ANF was greater during H75 than N75. CONCLUSION: Plasma levels of AVP, Aldo, and ARP increase during exercise when a threshold is reached and thereafter are dependent on the absolute workload, without any specific effect of hypoxia. The time course of ANF appears to be different from that of the other hormones.     

Cardiovascular responses to apnea during dynamic exercise

Breath holding maneuvers induce hypoxia, hypercapnia, and various cardiovascular responses typically including increases in total peripheral resistance, mean arterial pressure (MAP) and decreases in heart rate (HR). During dynamic exercise these responses may have a generally negative impact on performance. Moreover, they deserve particular attention in cardiovascular risk subjects. In 26 healthy sport students we studied the HR and MAP effects induced by the combination of dynamic exercise (cycle ergometry, 30 W and 250 W) with 20 s of either respiratory arrest (mouth piece pressure held constant at 20 mm Hg), free breathing, or rebreathing, i. e. periods of unimpeded breathing leading to similar levels of hypercapnia and hypoxia as the respiratory arrest. The measurements yielded no major differences between the conditions of rebreathing and free breathing. In contrast, 20 s of apnea led to a marked increase in MAP and a HR depression at both levels of exercise intensity. Additionally, there was a delayed MAP recovery after this stimulus. The present findings show that breath holding has marked effects on MAP and HR during dynamic exercise, which are essentially independent of the resulting hypoxia and of increases in intrathoracic pressure. The key factor seems to be an increase in total peripheral resistance, probably including a vasoconstriction in the exercising muscles.     

Exercise training and response to stress: insights from an animal model

The effect of training on the sympathoadrenal and cardiovascular responses to stress was examined in borderline hypertensive rats (BHRs). Animals trained with swimming showed reduced heart rates and plasma norepinephrine and epinephrine levels in response to novel foot shock stress. In contrast, systolic blood pressure was significantly higher in trained BHRs during the stress. Parasympathetic blockade with atropine sulfate (1 mg.kg-1 IV) had little effect on heart rate during stress in untrained rats but significantly elevated the stress-induced heart rate of trained animals. The reduction in stress reactivity produced by exercise training is not manifested in all physiological variables and increases in parasympathetic tone contribute strongly to the attenuated reactivity in heart rate.     

高原化学毒剂伤的伤情特点和机制研究

系统回顾了高原化学毒剂伤伤情特点和发生机制研究进展。高原环境影响人体健康的主要因素是低压缺氧。在既往的20年内,国内外建立了一系列模拟高原缺氧的实验技术和模型。利用这些技术进行的实验研究结果表明,高原缺氧复合化学中毒时,缺氧和中毒两种因素同时作用于机体,使病理生理反应、毒物代谢过程、中毒表现及药物效应等发生变化,常规的救治方案是否合适,值得进行更深入地探讨。     

Responses of peripheral blood mononuclear cells to moderate exercise and hypoxia

The purpose of this study was to analyze the physiological features of peripheral blood mononuclear cells (PBMCs) isolated from healthy female trekkers before and after physical activity carried out under both normoxia (low altitude, < 2000 m a.s.l.) and hypobaric hypoxia (high altitude, > 3700 m a.s.l.). The experimental design was to differentiate effects induced by exercise and those related to external environmental conditions. PBMCs were isolated from seven female subjects before and after each training period. The PBMCs were phenotypically and functionally characterized using fluorimetric and densitometric analyses, to determine cellular activation, and their intracellular Ca²⁺ levels and oxidative status. After a period of normoxic physical exercise, the PBMCs showed an increase in fully activated T lymphocytes (CD3⁺CD69⁺) and a reduction in intracellular Ca²⁺ levels. On the other hand, with physical exercise performed under hypobaric hypoxia, there was a reduction in T lymphocytes and an increase in nonactivated B lymphocytes, accompanied by a reduction in O₂^? levels in the mitochondria. These outcomes reveal that in women, low‐ to moderate‐intensity aerobic trekking induces CD69 T cell activation and promotes anti‐stress effects on the high‐altitude‐induced impairment of the immune responses and the oxidative balance.     

Blood pressure responses to acute static and dynamic exercise in three racial groups

PURPOSE: African Americans have a higher incidence of hypertension than other racial groups. Furthermore, some research suggests that normotensive individuals who exhibit exaggerated blood pressure (BP) responses to exercise may be at risk for future hypertension. This study sought to determine whether normotensive African Americans exhibited exaggerated BP responses to static exercise or dynamic exercise relative to Caucasian Americans and Asian Americans. METHODS: Thirty normotensive subjects participated from each of the three racial groups (15 men and 15 women). Subjects held 30% of maximal voluntary contraction (right knee extension) for 3 min, and BP was recorded during the 3rd min. On a separate occasion, subjects cycled for six min at a power equivalent to 70% of VO2 reserve, and BP was recorded during the 6th min. RESULTS: Static exercise produced large, significant increases in both systolic and diastolic BP (35 +/- 1.5 and 29 +/- 1.3 mm Hg, respectively). Dynamic exercise produced large, significant increases in systolic BP (51 +/- 1.6 mm Hg) and moderate, yet significant, increases in diastolic BP (8 +/- 1.0 mm Hg). There were no significant differences between racial groups in BP response to either static exercise or dynamic exercise. However, during dynamic exercise, men had a higher systolic BP response than did women. CONCLUSIONS: African Americans who are normotensive at rest do not exhibit a greater BP response to static exercise or dynamic exercise than do Caucasian Americans or Asian Americans.