The immediate effect of aerobic exercise on haemostatic parameters in patients with recently diagnosed mild to moderate essential hypertension

Effects of acute and chronic exercise in patients with essential hypertension: benefits and risks

The importance of regular physical activity in essential hypertension has been extensively investigated over the last decades and has emerged as a major modifiable factor contributing to optimal blood pressure control. Aerobic exercise exerts its beneficial effects on the cardiovascular system by promoting traditional cardiovascular risk factor regulation, as well as by favorably regulating sympathetic nervous system (SNS) activity, molecular effects, cardiac, and vascular function. Benefits of resistance exercise need further validation. On the other hand, acute exercise is now an established trigger of acute cardiac events. A number of possible pathophysiological links have been proposed, including SNS, vascular function, coagulation, fibrinolysis, and platelet function. In order to fully interpret this knowledge into clinical practice, we need to better understand the role of exercise intensity and duration in this pathophysiological cascade and in special populations. Further studies in hypertensive patients are also warranted in order to clarify the possibly favorable effect of antihypertensive treatment on exercise-induced effects.

Diurnal variation of haemostatic response to exercise in young sedentary males

The aim of this study was to evaluate diurnal variations in the haemostatic response to submaximal exercise performed by young, sedentary men. Fifteen healthy young sedentary males aged 25.6 ± 1.34 (mean ± SD) years performed two exercise sessions, morning and evening, at 70% of maximal oxygen consumption (V.O₂max) on a cycle ergometer for 30 min. Platelet count (PC), activated partial thromboplastin time (aPTT), prothrombin time (PT), fibrinogen, tissue plasminogen activator (tPA) and plasminogen activator inhibitor-1 (PAI-1) activity were measured as dependent variables. Exercise produced significant increases in PC and fibrinogen for both sessions (P ≤ 0.05), which returned to the resting values after recovery only in the evening session. APTT and PT shortened immediately after exercise, which remained after recovery for both sessions (P ≤ 0.01). Exercise presented significant increases in tPA activity (P ≤ 0.001), which returned to the baseline after recovery in both exercises. PAI-1 activity was significantly higher during the morning than evening (P ≤ 0.05), but no longer demonstrated exercise-related changes. It was found that exercise caused activation of both coagulation and fibrinolysis processes, partly related to the time of the day when the exercise was performed.

Platelet flow cytometry

Flow cytometry is a powerful and versatile tool which can be used to provide substantial phenotypic data on platelets by yielding quantitative information of their physical and antigenic properties. This includes surface expression of functional receptors, bound ligands, expression of granule components, interaction of platelets with other platelets via aggregation, or interaction with other blood components, such as leukocytes or the plasma coagulation system. Quantitative assessment of these parameters may facilitate the diagnosis of inherited or acquired platelet disorders, assist in the diagnosis of diseases associated with platelet activation, or assist in the monitoring of safety and efficacy of antiplatelet therapy.

Prolonged platelet activation in individuals with elevated blood pressure in response to a moderate exercise challenge

We examined the magnitude of 20-min moderate exercise-induced platelet activation in 50 volunteers with normal (n=31) or elevated blood pressure (EBP; n=19). Blood was drawn before, immediately after, and 25 min after exercise. Antibody-staining for platelet activation markers, P-selectin, and fibrinogen receptors was done with and without adenosine diphosphate (ADP) stimulation in whole blood for flow cytometric analyses. Exercise led to increases in percent aggregated platelets and percent platelets expressing P-selectin or PAC-1 binding (ps< or =.001). This increase in percent platelets expressing P-selectin continued even after a 25-min rest only in the EBP group (p< or =.01) accompanied by an increase in percent of aggregated platelets (p< or =.05). Although ADP stimulation led to increased platelet activation at rest, it was attenuated following exercise, even among EBP individuals. A moderate exercise challenge induced prolonged platelet activation in individuals with EBP but attenuation in activation to further stimulation by an agonist. Findings suggest that a recovery period after physical stress appears critical in individuals with high BP regarding platelet activation and aggregation, which can lead to an acute coronary syndrome in vulnerable individuals.

The effects of maximal treadmill graded exercise testing on haemorheological, haemodynamic and flow cytometry platelet markers in patients with systolic or diastolic heart failure

BACKGROUND

Acute exercise has been associated with activation of thrombosis, and this risk may be accentuated in patients with heart failure. Given the relation of platelets to atherothrombosis, we tested the hypothesis that acute exercise would adversely affect platelet indices and platelet activation markers in patients with systolic and diastolic heart failure.

MATERIALS AND METHODS

We studied 20 patients with systolic heart failure (17 men, 3 women; mean age 64 +/- 10 years, all with ejection fraction (EF) < or = 40%) and 20 patients with diastolic heart failure (14 men, 6 women; mean age 64 +/- 8 years, mean EF = 66%) who were exercised to maximal intensity, who were compared to 13 healthy controls (6 men, 7 women; mean age 60 +/- 4 years, mean EF = 73%). We measured platelet indices (platelet volume, mass and component) and platelet activation markers (platelet-bound CD62P%G, CD63%G and CD40L%G using flow cytometry, as well as plasma sCD40L and soluble P-selectin (sP-sel) levels).

RESULTS

Baseline Mean Platelet Volume (MPV), sP-sel, CD40L%G and CD63%G levels were significantly higher in patients with systolic and diastolic heart failure, when compared with controls. The mean exercise duration and VO(2 )peak in patients with systolic and diastolic heart failure were not significantly different, but lower than that seen in healthy controls. Following exercise, mean haematocrit, CD62P%G, and CD63%G significantly increased in all three subject groups (all P < 0.05). The proportional change in CD62P%G and CD63%G were not significantly different between healthy controls and heart failure patients (P > 0.05).

CONCLUSION

Acute maximal graded exercise increases platelet activation markers, with no disproportionate differences between heart failure patients and healthy controls, despite the former group having a lower exercise tolerance and VO2 peak.