Blood hemostasis in exercise and training

Concerns about the application of resistance exercise with blood-flow restriction and thrombosis risk in hemodialysis patients

BACKGROUND

Hemodialysis (HD) per se is a risk factor for thrombosis. Considering the growing body of evidence on blood-flow restriction (BFR) exercise in HD patients, identification of possible risk factors related to the prothrombotic agent D-dimer is required for the safety and feasibility of this training model. The aim of the present study was to identify risk factors associated with higher D-dimer levels and to determine the acute effect of resistance exercise (RE) with BFR on this molecule.

METHODS

Two hundred and six HD patients volunteered for this study (all with a glomerular filtration rate of <15 mL/min/1.73 m2). The RE + BFR session consisted of 50% arterial occlusion pressure during 50 min sessions of HD (intradialytic exercise). RE repetitions included concentric and eccentric lifting phases (each lasting 2 s) and were supervised by a strength and conditioning specialist.

RESULTS

Several variables were associated with elevated levels of D-dimer, including higher blood glucose, citrate use, recent cardiovascular events, recent intercurrents, higher inflammatory status, catheter as vascular access, older patients (>70 years old), and HD vintage. Furthermore, RE + BFR significantly increases D-dimer after 4 h. Patients with borderline baseline D-dimer levels (400-490 ng/mL) displayed increased risk of elevating D-dimer over the normal range (≥500 ng/mL).

CONCLUSION

These results identified factors associated with a heightened prothrombotic state and may assist in the screening process for HD patients who wish to undergo RE + BFR. D-dimer and/or other fibrinolysis factors should be assessed at baseline and throughout the protocol as a precautionary measure to maximize safety during RE + BFR.

Exercise transiently increases the density of incipient blood clots in antiplatelet-treated lacunar stroke patients

INTRODUCTION

Older individuals and, in particular, individuals at risk of recurrent stroke, may be susceptible to thrombosis when participating in exercise, however, this aspect has not been well investigated.

METHODS

Clot microstructure and conventional markers of thrombotic risk were determined in twenty lacunar stroke patients and fifteen healthy age-matched controls before, immediately after and 1 h after a bout of moderate intensity cycling exercise. Data were analyzed using a linear mixed model approach.

RESULTS

At rest, clot microstructure (1.69 ± 0.07 vs. 1.64 ± 0.05, corresponding to a difference of ~ 50% in normalized clot mass; p = 0.009) and thrombocyte count (73%; p < 0.0001) were higher, and activated partial thromboplastin time was lower (18%; p = 0.0001) in stroke patients compared to age-matched controls. Acute exercise increased thrombogenic markers similarly in the two groups: incipient clot microstructure (1.69 ± 0.07 vs. 1.74 ± 0.05; p = 0.0004 and 1.64 ± 0.05 vs. 1.71 ± 0.04; p < 0.0001, for stroke and controls respectively), plasma fibrinogen (12%; p < 0.0001 and 18%; p < 0.0001, for stroke and controls respectively) and the combined coagulation factors II, VII and X (p = 0.0001 and p < 0.0001, for stroke and controls respectively).

CONCLUSION

The results show that exercise transiently increases the risk of blood clot formation in both stroke patients and controls, however, due to the higher baseline thrombogenicity in stroke patients, the post exercise risk of forming blood clots may be higher in this group.

TRIAL REGISTRATION

Registered at ClinicalTrials.gov (NCT03635177).

The influence of the CYP1A2-163 C>A polymorphism on the hemostatic response to exercise following caffeine supplementation

BACKGROUND

Prior work from our group suggests that caffeine increases thrombotic potential after acute exercise. The aim of this study was to determine if hemostatic responses to exercise affected by caffeine are influenced by the CYP1A2-163 C>A polymorphism.

METHODS

Forty-two healthy men performed two trials in which a graded maximal exercise test was completed one hour after consuming either 6 mg/kg of caffeine or placebo. Subjects were categorized as possessing the C allele (N.=21) or being homozygous for the A allele (N.=21).

RESULTS

Factor VIII increased more (265%) during exercise in the caffeinated condition than the placebo condition (178%) (P<0.05). Tissue plasminogen activator (tPA) activity also increased more following caffeine as compared to placebo (increase of 8.70±4.32 IU/mL vs. 6.77±3.79 IU/mL respectively, P<0.05). There was no treatment × genotype or treatment × time × genotype interactions.

CONCLUSIONS

Although caffeine increases factor VIII and tPA responses to maximal exercise, these changes are not influenced by the CYP1A2-163 C>A polymorphism.

The Fibrinolytic System in Peripartum Depression

The relationship between depression and reduced fibrinolytic activity reflects the role of tissue plasminogen activator and plasmin in brain remodeling underlying resilience, depression remission, and reward processing, rather than the dissolution of fibrin clots. Individuals who experience depression demonstrate hippocampal and prefrontal cortex atrophy, as well as impaired neuronal connectivity. Brain-derived neurotrophic factor (BDNF), synthesized as a precursor that is activated through cleavage by tissue plasminogen activator and plasmin, influences adult neurogenesis and neuronal plasticity in the hippocampus and prefrontal cortex. Depression is associated with decreased brain levels of BDNF, due to reduced activity of tissue plasminogen activator and plasmin. Tissue plasminogen activator and plasmin also mediate the release of dopamine, a neurotransmitter implicated in motivation and reward. Peripartum depression defines a depressive episode that occurs during pregnancy or in the first month after delivery, reinforcing the concept that postpartum depression may be a continuum of antenatal depression. This article describes the fibrinolytic status in the healthy brain, in stress and depression, emphasizing the links between biological markers of depression and defective fibrinolysis. It also discusses the association between hypofibrinolysis and risk factors for perinatal depression, including polycystic ovary syndrome, early miscarriage, preeclampsia, stressful life events, sedentariness, eating habits, gestational and type 2 diabetes, and antithyroid peroxidase antibodies. In addition, it reviews the evidence that antidepressant medications and interventions as diverse as placebo, psychotherapy, massage, video game playing, regular exercise, dietary modifications, omega 3 fatty acid supplementation, neurohormones, and cigarette smoking may reduce depression by restoring the fibrinolytic activity. Last, it suggests new directions for research.

Global thrombosis test for assessing thrombotic status and efficacy of antithrombotic diet and other conditions

Because of the high mortality from myocardial infarction and stroke, there is a great demand for finding novel methods of diagnosis, prevention and treatment of these diseases. Most of the current tests measure important determinants of thrombosis such as platelet function, coagulation and fibrinolysis in isolation; therefore, a global test measuring the actual thrombotic status would be more useful in clinical conditions. We obtained considerable experience by using the global thrombosis test, which determines the actual thrombotic status by taking into account the measured platelet reactivity, coagulation and fibrinolytic activities. In animal experiments, we found significant correlation between the ex vivo global thrombosis test measurements and the in vivo thrombotic status. The published evidence for the benefit of an antithrombotic diet with regular physical exercise is also described.

There is a great concern in the general population how to detect the risk of thrombotic events and prevent the high mortality from stroke, myocardial infarction, sudden death and cancer-associated thrombosis. Our experience on antithrombotic fruits and vegetables intake and regular exercise assessed by the global thrombosis test suggested a potentially unique way of preventing these life-threatening diseases. In addition, global thrombosis testing may offer some benefit in detecting risk of thrombotic of forthcoming thrombotic events in cancer and COVID-19 virus-infected patients.

Transferring clinically established immune inflammation markers into exercise physiology: focus on neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio and systemic immune-inflammation index

Over the last decades the cellular immune inflammation markers neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR) and systemic immune-inflammation index (SII = NLR × platelets) have emerged in clinical context as markers of disease-related inflammation and are now widely appreciated due to their integrative character. Transferring these clinically established inflammation markers into exercise physiology seems highly beneficial, especially due to the low temporal, financial and infrastructural resources needed for assessment and calculation. Therefore, the aim of this review is to summarize evidence on the value of the integrative inflammation markers NLR, PLR and SII for depiction of exercise-induced inflammation and highlight potential applications in exercise settings. Despite sparse evidence, multiple investigations revealed responsiveness of the markers to acute and chronic exercise, thereby opening promising avenues in the field of exercise physiology. In performance settings, they might help to infer information for exercise programming by reflecting exercise strain and recovery status or periods of overtraining and increased infection risk. In health settings, application involves the depiction of anti-inflammatory effects of chronic exercise in patients exhibiting chronic inflammation. Further research should, therefore, focus on establishing reference values for these integrative markers in athletes at rest, assess the kinetics and reliability in response to different exercise modalities and implement the markers into clinical exercise trials to depict anti-inflammatory effects of chronic exercise in different patient collectives.

Effects of a 1-Year Physical Activity Intervention on Markers of Hemostasis among Breast Cancer Survivors: A Randomized Controlled Trial

Introduction  Physical activity may reduce the development of breast cancer. Whereas hypercoagulability has been linked to adverse outcomes in breast cancer patients, the effects of physical activity on their hemostatic factors are unknown. The study aimed to assess whether long-term (1 year) physical activity can affect hemostatic factors in breast cancer patients. Methods  Fifty-five women (35-75 years) with invasive breast cancer stage I/II were randomized to a physical activity intervention ( n  = 29) lasting 1 year or to a control group ( n  = 26), and analyzed as intention to treat. Fibrinogen, factor VII antigen, tissue factor pathway inhibitor, and von Willebrand factor (VWF) antigen as well as prothrombin fragment 1 + 2, the endogenous thrombin potential and D-dimer, were measured in plasma before intervention (baseline), and then after 6 and 12 months. Results  Maximal oxygen uptake (measure of cardiorespiratory fitness) decreased the first 6 months among the controls, but remained stable in the intervention group. We found no significant differences between the two study groups regarding any of the hemostatic factors, except a significantly higher increase in factor VII antigen in the intervention group. The effect of the intervention on VWF was, however, significantly affected by menopausal stage, and a significant effect of the intervention was found on VWF among postmenopausal women, even after adjustment for dietary intake. Conclusion  Long-term physical activity had no effect on the majority of the hemostatic factors measured, but led to increased plasma concentrations of factor VII antigen and prevented an increase in VWF concentration after breast cancer treatment in postmenopausal women. The clinical impact of these findings for risk of vascular thrombosis warrants further studies.

Acute responses of platelet count and ADP-induced platelet aggregation to different high intensity interval exercise modes

BACKGROUND

Platelet activation is associated with abdominal obesity and exercise training is an important modulator of body weight.

OBJECTIVE

We investigated the effects of two high intensity interval exercise (HIIE) protocols of different intensity and duration on platelet indices and platelet aggregation in overweight men.

METHODS

Ten overweight men performed 6 intervals of 30s exercise at 110% of peak power output (PPO) interspersed by 3 : 30 min active recovery (1/7 protocol) at 40% of PPO and 6 intervals of 2 min exercise at 85% of PPO interspersed by 2 min active recovery (1/1 protocol) at 30% of PPO in two separate sessions. Platelet indices and platelet aggregation were measured before and immediately after both HIIEs.

RESULTS

Platelet indices increased significantly following HIIE (P < 0.05), though, significant differences between the two protocols were only detected for platelet count, which was markedly increased following 1/1 protocol. Platelet aggregation increased significantly (P < 0.05) in response to the two HIIE protocols, with no significant difference being observed between the two protocols (P > 0.05).

CONCLUSIONS

It is concluded that HIIE leads to transient increases in markers of thrombus formation and that work to rest ratio is an important factor when investigating the changes in thrombocytosis following HIIE.

Physical Activity and Thrombophilic Risk in a Short Series

The role of influence on protein C anticoagulant system and PC deficiency-related thrombophilic risk due to strenuous physical exercise is still under discussion. To investigate the modification of the protein C anticoagulant pathway after vigorous exercise, we measured ProC^® Global assay, a protein C activity dependent clotting time, in 20 healthy subjects before and immediately after maximal treadmill exercise, and at 5, 15, 30 and 60 min in the recovery phase. The most evident change was a shortening of ProC^® Global clotting time from the average basal value of 123 sec to 84 sec at 30 min in post-exercise. Our study shows that the coagulation unbalance observed after strenuous exercise and with no consequence in healthy individuals with normal PC level, could increase the thrombophilic risk in silent carriers of significant defects of the protein C system and occasionally trigger an episode of deep vein thrombosis.

Acquired von Willebrand Syndrome Associated with Cardiovascular Diseases

The blood glycoprotein von Willebrand factor (VWF) plays an important role in hemostasis and thrombosis. VWF is produced and secreted as large multimers by endothelial cells and megakaryocytes. It is then cleaved in a sheer-stress dependent manner by a specific protease, ADAMTS13, into multimers consisting of 2–80 subunits. Among VWF multimers, high molecular weight (HMW) multimers play important roles in platelet aggregation. Therefore, their loss induces a hemostatic disorder known as von Willebrand disease (VWD) type 2A. Various cardiovascular diseases, such as aortic stenosis, hypertrophic obstructive cardiomyopathy (HOCM), and several congenital structural diseases, as well as mechanical circulatory support systems, generate excessive high shear stress in the bloodstream. These cause excessive cleavage of VWF multimers resulting in a loss of HMW multimers, known as acquired von Willebrand syndrome (AVWS), a hemostatic disorder similar to VWD type 2A. Bleeding often occurs in the gastrointestinal tract since a fragile angiodysplasia develops associated with these diseases. Radical treatment for AVWS is to remove the pathological high shear causing AVWS.

Exercise-Derived Microvesicles: A Review of the Literature

Initially suggested as simple cell debris, cell-derived microvesicles (MVs) have now gained acceptance as recognized players in cellular communication and physiology. Shed by most, and perhaps all, human cells, these tiny lipid-membrane vesicles carry bioactive agents, such as proteins, lipids and microRNA from their cell source, and are produced under orchestrated events in response to a myriad of stimuli. Physical exercise introduces systemic physiological challenges capable of acutely disrupting cell homeostasis and stimulating the release of MVs into the circulation. The novel and promising field of exercise-derived MVs is expanding quickly, and the following work provides a review of the influence of exercise on circulating MVs, considering both acute and chronic aspects of exercise and training. Potential effects of the MV response to exercise are highlighted and future directions suggested as exercise and sports sciences extend the realm of extracellular vesicles.

Effect of ABO blood group on haemostatic parameters in severe haemophilia A patients performing acute moderate-intensity exercise

: The primary objective was to assess the effect of ABO blood group on von Willebrand factor (VWF) rise induced by four bouts of moderate-intensity physical activity, on pharmacokinetics of a B-domain-deleted recombinant FVIII (BDD-rFVIII), and haemostatic parameters in severe haemophilia A patients with a null mutation. The secondary objective was to compare the response to exercise according to infused product type in a subgroup of patients who previously participated to the same exercise protocol, while treated with a full length recombinant FVIII (FL-rFVIII). Twenty patients had two visits (rest and exercise). Blood samples were drawn before administration of BDD-rFVIII and at 6 time points, until 24 h postinfusion. FVIII activity increased transiently by 1.1-fold, but only after the first exercise session, as compared to rest. VWF:Ag and platelet count were significantly elevated after each session. Mean FVIII half-life and thromboelastography measurements were unchanged with exercise. However, 14 participants had a slight variation of FVIII half-life with exercise compared to rest (from -3.42 h to +2.51 h). Seven patients demonstrated a longer FVIII half-life (four with O blood group), whereas the remainders had a reduced half-life (three with O blood group). FVIII half-life correlated with baseline VWF:Ag at rest (r = 0.70, P < 0.001) and with exercise (r = 0.67, P < 0.002). Recovery was different between FL-rFVIII and BDD-rFVIII at rest (P = 0.032), but no significant differences were observed between half-life of products at rest and with exercise. ABO blood group and the type of rFVIII administered did not influence the response to exercise.

Immune-regulating effects of exercise on cigarette smoke-induced inflammation

Long-term cigarette smoking (LTCS) represents an important risk factor for cardiac infarction and stroke and the central risk factor for the development of a bronchial carcinoma, smoking-associated interstitial lung fibrosis, and chronic obstructive pulmonary disease. The pathophysiologic development of these diseases is suggested to be promoted by chronic and progressive inflammation. Cigarette smoking induces repetitive inflammatory insults followed by a chronic and progressive activation of the immune system. In the pulmonary system of cigarette smokers, oxidative stress, cellular damage, and a chronic activation of pattern recognition receptors are described which are followed by the translocation of the NF-kB, the release of pro-inflammatory cytokines, chemokines, matrix metalloproteases, and damage-associated molecular patterns. In parallel, smoke pollutants cross directly through the alveolus-capillary interface and spread through the systemic bloodstream targeting different organs. Consequently, LTCS induces a systemic low-grade inflammation and increased oxidative stress in the vascular system. In blood, these processes promote an increased coagulation and endothelial dysfunction. In muscle tissue, inflammatory processes activate catabolic signaling pathways followed by muscle wasting and sarcopenia. In brain, several characteristics of neuroinflammation were described. Regular exercise training has been shown to be an effective nonpharmacological treatment strategy in smoke-induced pulmonary diseases. It is well established that exercise training exerts immune-regulating effects by activating anti-inflammatory signaling pathways. In this regard, the release of myokines from contracting skeletal muscle, the elevations of cortisol and adrenalin, the reduced expression of Toll-like receptors, and the increased mobilization of immune-regulating leukocyte subtypes might be of vital importance. Exercise training also increases the local and systemic antioxidative capacity and several compensatory mechanisms in tissues such as an increased anabolic signaling in muscle or an increased compliance of the vascular system. Accordingly, regular exercise training seems to protect long-term smokers against some important negative local and systemic consequences of smoking. Data suggest that it seems to be important to start exercise training as early as possible.

Elderly-customized hatha yoga effects on the vascular inflammation factors of elderly women

[Purpose] The aim of this study was to examine the effects of the application of elderly-customized hatha yoga on the vascular inflammation factors of elderly women. [Subjects and Methods] This research was conducted with 14 elderly women, between 70 and 80 years old, divided into an elderly-customized hatha yoga group (n=7) and a control group (n=7). The application group participated in a hatha yoga program designed to be elderly-friendly for 10 weeks. At the end of the program, the vascular inflammation factors were measured, including the albumin, white blood cell count, fibrinogen, high sensitivity C-reactive protein (hs-CRP), and erythrocyte sedimentation rate (ESR). [Results] In the hatha yoga group, the albumin increased significantly after the application, when compared to the level before the application, while the fibrinogen, hs-CRP, and ESR decreased significantly. In the control group, the vascular inflammation factor levels before and after the application period were not significantly different. [Conclusion] Based on the results of this study, the application of elderly-customized hatha yoga created positive changes in the vascular inflammation factors of elderly women.

Exercise training reverses inflammation and muscle wasting after tobacco smoke exposure

Long-term cigarette smoking induces inflammatory processes in the pulmonary system that are suggested to "spill over" into systemic inflammation. Regular exercise has been shown to have anti-inflammatory properties. The aim of the study was to investigate the effects of therapeutic exercise on inflammation and muscle wasting in smoke-exposed mice. C57BL/6J mice ( n = 30) were separated into three groups to receive either 1) no specific treatment (control group), 2) 8-mo exposure to cigarette smoke [smoke-exposed (SE) group], or 3) 8 mo of cigarette smoke combined with exercise training during the last 2 mo (SEex group). The inflammatory status was analyzed by quantifying levels of various plasma proteins using multiplex ELISA and detection of lymphocyte surface markers by flow cytometry. Muscle tissue was analyzed by histological techniques and measurements of RNA/protein expression. SE led to decreased maximal O₂ uptake (V̇o_2max) and maximal running speed ( V_max), which was reversed by exercise ( P < 0.05). Expression of ICAM-1, VCAM-1, and CD62L on T cells increased and was reversed by exercise ( P < 0.05). Similarly, SE induced an increase of various inflammatory cytokines, which were downregulated by exercise. In muscle, exercise improved the structure, oxidative capacity, and metabolism by reducing ubiquitin proteasome system activation, stimulating insulin-like growth factor 1 expression, and the SE-induced inhibition of mammalian target of rapamycin signaling pathway ( P < 0.05). Exercise training reverses smoke-induced decline in exercise capacity, systemic inflammation, and muscle wasting by addressing immune-regulating, anabolic, and metabolic pathways.

Effects of a Single Bout of Resistance Exercise in Different Volumes on Endothelium Adaptations in Healthy Animals

Background:

Resistance exercise (RE) has been recommended for patients with cardiovascular diseases. Recently, a few studies have demonstrated that the intensity of a single bout of RE has an effect on endothelial adaptations to exercise. However, there is no data about the effects of different volumes of RE on endothelium function.

Objective:

The aim of the study was to evaluate the effects of different volumes of RE in a single bout on endothelium-dependent vasodilatation and nitric oxide (NO) synthesis in the mesenteric artery of healthy animals.

Methods:

Male Wistar rats were divided into three groups: Control (Ct); low-volume RE (LV, 5 sets x 10 repetitions) and high-volume RE (HV, 15 sets x 10 repetitions). The established intensity was 70% of the maximal repetition test. After the exercise protocol, rings of mesenteric artery were used for assessment of vascular reactivity, and other mesenteric arteries were prepared for detection of measure NO production by DAF-FM fluorescence. Insulin responsiveness on NO synthesis was evaluated by stimulating the vascular rings with insulin (10 nM).

Results:

The maximal relaxation response to insulin increased in the HV group only as compared with the Ct group. Moreover, the inhibition of nitric oxide synthesis (L-NAME) completely abolished the insulin-induced vasorelaxation in exercised rats. NO production showed a volume-dependent increase in the endothelial and smooth muscle layer. In endothelial layer, only Ct and LV groups showed a significant increase in NO synthesis when compared to their respective group under basal condition. On the other hand, in smooth muscle layer, NO fluorescence increased in all groups when compared to their respective group under basal condition.

Conclusions:

Our results suggest that a single bout of RE promotes vascular endothelium changes in a volume-dependent manner. The 15 sets x 10 repetitions exercise plan induced the greatest levels of NO synthesis.

Fundamentos:

O exercício resistido (ER) tem sido recomendado para pacientes com doenças cardiovasculares. Recentemente, alguns estudos demonstraram que a intensidade de uma sessão de ER exerce um efeito sobre a disfunção endotelial. No entanto, não há dados sobre os efeitos de diferentes volumes de ER sobre a função endotelial.

Objetivo:

O objetivo deste estudo foi avaliar os efeitos de diferentes volumes de ER, realizados em uma única sessão, sobre a vasodilatação dependente do endotélio e síntese de óxido nítrico (NO) em artéria mesentérica de animais saudáveis.

Métodos:

Ratos Wistar machos foram divididos em três grupos: Controle (Ct); baixo volume (BV, 5 séries x 10 repetições) e alto volume de ER (AV, 15 séries x 10 repetições). Foi estabelecida a intensidade de 70% do teste de repetição máxima. Após o protocolo de exercício, anéis de artéria mesentérica foram utilizados na avaliação da reatividade vascular, e outras artérias mesentéricas foram preparadas para a detecção da produção de NO por fluorescência com para do DAF-FM. A resposta à insulina pela síntese de NO foi avaliada estimulando-se os anéis vasculares com insulina (10nM).

Resultados:

A resposta máxima do relaxamento induzido por insulina foi aumentada somente no grupo AV em comparação ao grupo Ct. Além disso, a inibição da síntese do NO (L-NAME), aboliu completamente o relaxamento vascular induzido por insulina em ratos exercitados. A produção de NO mostrou um aumento dependente do volume no endotélio e no músculo liso. No endotélio, apenas os grupos Ct e BV mostraram aumento significativo na síntese de NO quando comparado aos seus respectivos grupos sob condição basal. No entanto, no músculo liso, a fluorescência foi aumentada em todos os grupos quando comparados aos seus respectivos grupos sob a condição basal.

Conclusões:

Nossos resultados sugerem que uma única sessão de ER foi capaz de promover adaptações no endotélio vascular. Além disso, nós observamos que este efeito é volume-dependente e o volume de 15 séries x10 repetições induziu o maior aumento na síntese de NO.

The exercise paradox may be solved by measuring the overall thrombotic state using native blood

While exercise is widely believed to prevent atherothrombotic diseases, it occasionally causes sudden death. This exercise paradox may be due to the inadequate testing of the thrombotic and thrombolytic status. A recently developed shear-induced thrombosis/endogenous fibrinolysis test performed with non-anticoagulated blood samples allows the assessment of the thrombotic state of an individual both at rest and after exercise. This sensitive and physiologically relevant test may help to solve the aforementioned exercise paradox.

Patterns of expression of factor VIII and von Willebrand factor by endothelial cell subsets in vivo

Circulating factor VIII (FVIII) is derived from liver and from extrahepatic sources probably of endothelial origin, but the vascular sites of FVIII production remain unclear. Among organs profiled, only liver and lymph nodes (LNs) show abundant expression of F8 messenger RNA (mRNA). Transcriptomic profiling of subsets of stromal cells, including endothelial cells (ECs) from mouse LNs and other tissues, showed that F8 mRNA is expressed by lymphatic ECs (LECs) but not by capillary ECs (capECs), fibroblastic reticular cells, or hematopoietic cells. Among blood ECs profiled, F8 expression was seen only in fenestrated ECs (liver sinusoidal and renal glomerular ECs) and some high endothelial venules. In contrast, von Willebrand factor mRNA was expressed in capECs but not in LECs; it was coexpressed with F8 mRNA in postcapillary high endothelial venules. Purified LECs and liver sinusoidal ECs but not capECs from LNs secrete active FVIII in culture, and human and mouse lymph contained substantial

FVIII

C activity. Our results revealed localized vascular expression of FVIII and von Willebrand factor and identified LECs as a major cellular source of FVIII in extrahepatic tissues.

The acute effect of moderate intensity aquatic exercise on coagulation factors in haemophiliacs

The objective of this cross-sectional study was to analyse the acute effect of aquatic exercise on haemostasis in persons with haemophilia. Ten adult haemophiliacs (8 type A, 2 type B) familiarized with aquatic training performed a 20-min exercise session in a swimming pool at an intensity of ~70% maximum heart rate (HR). Blood samples were collected immediately after the training session. The haemostatic parameters selected for analyses were factor VIII (FVIII), prothrombin time (PT), activated partial thromboplastin time (APTT) and fibrinogen. There were unclear effects of the exercise bout on FVIII and APTT, with a possibly beneficial effect on PT (-11·4%; 90% confidence interval: -26·1;3·3%), and a trivial change on fibrinogen levels. It was found an association between the mean rise in HR during exercise and the decrement in PT after exercise (r = 0·729; P = 0·026). The greater changes were observed in the patients diagnosed with a moderate level of haemophilia. It is concluded that a short bout of moderate intensity of aquatic exercise may have a positive influence on PT in adults with haemophilia with greater changes in those individuals exhibiting a greater rise in HR during exercise. This may be an important issue to the haemostatic control of haemophiliacs in clinical settings. Further studies are warranted for testing the influence of different aquatic exercise intensities on haemostasis.

Performance related factors are the main determinants of the von Willebrand factor response to exhaustive physical exercise

Background

Physical stress triggers the endothelium to release von Willebrand Factor (VWF) from the Weibel Palade bodies. Since VWF is a risk factor for arterial thrombosis, it is of great interest to discover determinants of VWF response to physical stress. We aimed to determine the main mediators of the VWF increase by exhaustive physical exercise.

Methods

105 healthy individuals (18–35 years) were included in this study. Each participant performed an incremental exhaustive exercise test on a cycle ergometer. Respiratory gas exchange measurements were obtained while cardiac function was continuously monitored. Blood was collected at baseline and directly after exhaustion. VWF antigen (VWF:Ag) levels, VWF collagen binding (VWF:CB) levels, ADAMTS13 activity and common variations in Syntaxin Binding Protein-5 (STXBP5, rs1039084 and rs9399599), Syntaxin-2 (STX2, rs7978987) and VWF (promoter, rs7965413) were determined.

Results

The median VWF:Ag level at baseline was 0.94 IU/mL [IQR 0.8–1.1] and increased with 47% [IQR 25–73] after exhaustive exercise to a median maximum VWF:Ag of 1.38 IU/mL [IQR 1.1–1.8] (p<0.0001). VWF:CB levels and ADAMTS13 activity both also increased after exhaustive exercise (median increase 43% and 12%, both p<0.0001). The strongest determinants of the VWF:Ag level increase are performance related (p<0.0001). We observed a gender difference in VWF:Ag response to exercise (females 1.2 IU/mL; males 1.7 IU/mL, p = 0.001), which was associated by a difference in performance. Genetic variations in STXBP5, STX2 and the VWF promoter were not associated with VWF:Ag levels at baseline nor with the VWF:Ag increase.

Conclusions

VWF:Ag levels strongly increase upon exhaustive exercise and this increase is strongly determined by physical fitness level and the intensity of the exercise, while there is no clear effect of genetic variation in STXBP5, STX2 and the VWF promoter.

Thromboelastographic Study of Psychophysiological Stress: A Review

Thromboelastography (TEG) is drawing more attention for clinical and laboratory studies of hemostasis. It has been applied to evaluate the effects of both psychological and physiological stress on whole blood coagulation from the onset of the coagulation cascade through clot formation, to the end with fibrinolysis. We conducted a comprehensive review on the applications of TEG for assessment of different stressors, ranging from physical exercise to emotional situations. The methodology is unique in terms of instrumentation, the methods to activate blood coagulation, the type of blood (citrated vs fresh blood), and study settings (in vitro vs in vivo vs clinical trials). Thromboelastography has most often been used to study the effects of physiological stress. The author's own work and future directions are discussed as well. The review would facilitate future development of TEG for evaluating hemostasis and potential pathological pathways in response to various forms of stress.

Changes in blood coagulation induced by exercise training in young athletic horses

Prothrombin Time (PT), Activated Partial Prothrombin Time (APTT), Fibrinogen concentration (Fbg) and Platelet number (Plt) were evaluated in 20 young athletic horses during a training program. A standardized exercise test (SET) was performed every month for three months. The V4 variations (the speed, in m/min, reached at the blood lactate concentration of 4 mmol/l) obtained for each test were calculated to assess the effect of training program on athletic performance. Blood samples were collected at 20-day intervals over a period of 80 days from the beginning of the training program. The V4 (P < 0.001), PT (P < 0.001), APTT (P < 0.01), Fbg (P < 0.01) and Plt (P < 0.001) varied throughout the training period showing that the modifications of clotting mechanism in response to training period may be considered as a normal physiological response of the hemostatic system to training exercise.

Effects of a single bout of walking exercise on blood coagulation parameters in obese women

Obesity is associated with increased prevalence of thromboembolic events. We aimed to investigate whether obese women might benefit from vigorous aerobic exercise. Forty-two overweight and obese women performed a 30-min walking exercise test (treadmill ergometer) at an intensity of 70% of individual peak oxygen uptake. Blood samples were collected before and immediately after exercise. Thrombelastometry and platelet function measurements were performed on whole blood. Standard coagulation times, thrombin generation curves, markers of thrombin generation, fibrinolytic parameters, plasma levels of pro- and anticoagulatory factors, and microparticle procoagulant activity were determined in platelet-poor plasma samples. Thrombelastometry revealed a significant prolongation of clot formation time ( P = 0.037) and a significant deceleration of fibrin build up (alpha angle, P = 0.034) after exercise. Calibrated automated thrombography revealed a significant exercise-induced decrease in endogenous thrombin potential ( P = 0.039). Moreover, thrombin formation stopped earlier postexercise, reflected in shortened StartTail ( P = 0.046). Significantly elevated tissue-plasminogen activator levels ( P = 0.001) indicate an exercise-induced activation of the fibrinolytic system. White blood cell count increased significantly from pre- to postexercise ( P = 0.045), indicating a mild exercise-induced leukocytosis. The results of this study demonstrate that vigorous aerobic exercise might be a suitable tool to protect obese women from thrombotic events. We show that a single bout of vigorous aerobic exercise is clearly associated with an activation of the fibrinolytic system and a decreased readiness of the postexercise samples to form a clot and to generate thrombin, the pivotal enzyme of hemostasis.

The interactions between hemostasis and resistance training: a review

Physical inactivity is considered a risk factor for cardiovascular disease and is strongly associated with changes in arterial structure. Regular physical activity and exercise contributes to the prevention of coronary artery disease. Therefore, cardiovascular and resistance training improve hemostatic parameters and promote a less thrombotic blood profile. This review highlights the studies, mechanisms, and outcomes relating to the effectiveness of resistance training on the process of hemostasis. The Pubmed, Scopus, Medline, Scielo, Lilacs, Ibecs, and Cochrane databases were used to locate the original articles. Seventeen studies were found during the research process. Of these, ten articles were excluded. Those protocols using a high volume of training for young adults showed a greater fibrinolytic response, and training protocols with intensities above 80% of 1 maximum repetition showed an increased platelet activity. In subjects with coronary artery disease, just one session of resistance training resulted in improvement in the fibrinolytic system (tissue plasminogen activator) without raising potential thrombotic markers.

Physical inactivity and idiopathic pulmonary embolism in women: prospective study

OBJECTIVES

To determine the association between physical inactivity (that is, a sedentary lifestyle) and incident idiopathic pulmonary embolism.

DESIGN

Prospective cohort study.

SETTING

Nurses' Health Study.

PARTICIPANTS

69 950 female nurses who completed biennial questionnaires from 1990 to 2008. Main outcome measures The primary outcome was idiopathic pulmonary embolism confirmed in medical records. Multivariable Cox proportional hazards models controlled for age, body mass index (BMI), energy intake, smoking, pack years, race, spouse's educational attainment, parity, menopause, non-aspirin non-steroidal anti-inflammatory drugs, warfarin, multivitamin supplements, hypertension, coronary heart disease, rheumatological disease, and dietary patterns. The primary exposure was physical inactivity, measured in hours of sitting each day. The secondary exposure was physical activity, measured in metabolic equivalents a day.

RESULTS

Over the 18 year study period, there were 268 cases of incident idiopathic pulmonary embolism. There was an association between time of sitting and risk of idiopathic pulmonary embolism (41/104 720 v 16/14 565 cases in most inactive v least inactive in combined data; P<0.001 for trend). The risk of pulmonary embolism was more than twofold in women who spent the most time sitting compared with those who spent the least time sitting (multivariable hazard ratio 2.34, 95% confidence interval 1.30 to 4.20). There was no association between physical activity and pulmonary embolism (P=0.53 for trend).

CONCLUSIONS

Physical inactivity is associated with incident pulmonary embolism in women. Interventions that decrease time sitting could lower the risk of pulmonary embolism.

Thrombosis, physical activity, and acute coronary syndromes

Acute coronary syndromes (ACS) are common, life-threatening cardiac disorders that typically are triggered by rupture or erosion of an atherosclerotic plaque. Platelet deposition and activation of the blood coagulation cascade in response to plaque disruption lead to the formation of a platelet-fibrin thrombus, which can grow rapidly, obstruct coronary blood flow, and cause myocardial ischemia and/or infarction. Several clinical studies have examined the relationship between physical activity and ACS, and numerous preclinical and clinical studies have examined specific effects of sustained physical training and acute physical activity on atherosclerotic plaque rupture, platelet function, and formation and clearance of intravascular fibrin. This article reviews the available literature regarding the role of physical activity in determining the incidence of atherosclerotic plaque rupture and the pace and extent of thrombus formation after plaque rupture.

The effect of the acute submaximal exercise on thrombin activatable fibrinolysis inhibitor levels in young sedentary males

Depending on type, duration, and intensity of the exercise, changes occur in hemostasis. In this study, we evaluated the changes in the parameters of coagulation and fibrinolytic systems that happened after the submaximal aerobic exercises by bicycle ergomater. Twelve healthy male participants whose ages were between 21 and 28 have been included. The venous samples have been drawn before the exercise as well as at the 0 th, 15th, and 60th minutes after the submaximal exercise. The values of prothrombin time (PT), active partial thromboplastin time (aPTT), D-dimer, fibrinogen, plasminogen activator inhibitor 1 (PAI-1) and thrombin-activatable fibrinolysis inhibitor (TAFI) have been measured. Plasminogen activator inhibitor 1 values have shown an insignificant increase after exercise (P = .328), whereas, it has decreased significantly during the resting period (P = .033) Postexercise 15th and 60th minutes TAFI values have decreased significantly comparing to basal and postexercise (0 th minute) values (P = .001). Fibrinolytic system activation is observed after acute submaximal aerobic exercise of sedentary healthy participants.

Lower-extremity functional electrical stimulation decreases platelet aggregation and blood coagulation in persons with chronic spinal cord injury: a pilot study

BACKGROUND

Individuals with spinal cord injury (SCI) develop premature cardiovascular disease. Regular exercise reduces the incidence and symptoms of cardiovascular disease in able-bodied individuals; these salutary effects of exercise have not been documented in persons with SCI.

OBJECTIVE

To evaluate the effects of functional electrical stimulation leg cycle ergometry (FES-LCE) exercise training on platelet aggregation and blood coagulation in persons with SCI.

PARTICIPANTS

Subjects (n=14) with stable chronic (>1 year) paraplegia (T1-T10) or tetraplegia (C4-C8).

METHODS

Blood samples were collected before and after the first and eighth sessions (2 sessions per week for 4 weeks) of FES exercise.

RESULTS

Platelet aggregation was inhibited by 20% after the first session and by 40% (P < 0.001) after the eighth session. Thrombin activity was unchanged after the first session (10.7 +/- 0.85 s to 10.43 +/- 0.56 s) and decreased after the eighth session (12.5 +/- 1.98 s to 11.1 +/- 1.7 s; P < 0.0003). Antithrombin III activity increased after the first (103.8% +/- 8.9% to 110% +/- 6.9%; P < 0.0008) and eighth sessions (107.8% +/- 12.1% to 120.4% +/- 13.1%; P < 0.0001). Cyclic adenosine monophosphate increased after the first (9.9% + 2.5% to 15.8% +/- 3%; P < 0.001) and eighth sessions (17.8% +/- 4.2% to 36.5% +/- 7.6%; P < 0.0001). After the eighth session, factors V and X increased significantly (88% +/- 27% to 103% +/- 23%, P < 0.0001; 100% +/- 40% to 105% +/- 7%, P < 0.01, respectively); factors VII and VIII and fibrinogen did not change significantly. A significant reduction in platelet activation/aggregation was demonstrated in response to FES-LCE. The decrease in thrombin level was caused by the simultaneous increase in antithrombin activity.

CONCLUSION

These findings provide new insight into the potential protective effects of FES-LCE against the risk of cardiovascular disease.

Effect of resistance training on hematological blood markers in older men and women: a pilot study

The aim of this study was to examine the effects of resistance training on hematological blood markers in older individuals. Twenty-nine men and women participated to this study. Subjects were randomized in 2 groups: (1) control (n = 13) and (2) resistance training (n = 16). At baseline and after the intervention, subjects were submitted to a blood sample to determine their hematological profile (red blood cells, hemoglobin, hematocrit, platelets, leukocytes, neutrophils, lymphocytes, monocytes, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, red cell distribution width). At baseline, no difference was observed between groups. Moreover, we found no significant difference after the intervention on any of these markers. A 6-month resistance program in healthy older individuals seems to have no beneficial nor deleterious effects on hematological blood parameters. However, resistance training was well tolerated and should be recommended for other health purposes. Further studies are needed to confirm these results in a large population.

Nighttime vagal cardiac control and plasma fibrinogen levels in a population of working men and women

BACKGROUND

Elevated plasma fibrinogen levels have prospectively been associated with an increased risk of coronary artery disease in different populations. Plasma fibrinogen is a measure of systemic inflammation crucially involved in atherosclerosis. The vagus nerve curtails inflammation via a cholinergic antiinflammatory pathway. We hypothesized that lower vagal control of the heart relates to higher plasma fibrinogen levels.

METHODS

Study participants were 559 employees (age 17-63 years; 89% men) of an airplane manufacturing plant in southern Germany. All subjects underwent medical examination, blood sampling, and 24-hour ambulatory heart rate recording while kept on their work routine. The root mean square of successive differences in RR intervals during the night period (nighttime RMSSD) was computed as the heart rate variability index of vagal function.

RESULTS

After controlling for demographic, lifestyle, and medical factors, nighttime RMSSD explained 1.7% (P = 0.001), 0.8% (P = 0.033), and 7.8% (P = 0.007), respectively, of the variance in fibrinogen levels in all subjects, men, and women. Nighttime RMSSD and fibrinogen levels were stronger correlated in women than in men. In all workers, men, and women, respectively, there was a mean +/- SEM increase of 0.41 +/- 0.13 mg/dL, 0.28 +/- 0.13 mg/dL, and 1.16 +/- 0.41 mg/dL fibrinogen for each millisecond decrease in nighttime RMSSD.

CONCLUSIONS

Reduced vagal outflow to the heart correlated with elevated plasma fibrinogen levels independent of the established cardiovascular risk factors. This relationship seemed comparably stronger in women than men. Such an autonomic mechanism might contribute to the atherosclerotic process and its thrombotic complications.

The effect of exercise and training status on platelet activation: Do cocoa polyphenols play a role?

Sedentary and trained men respond differently to the same intensity of exercise, this is probably related to their platelet reactivity and antioxidant capacity. There is growing interest in the utilization of antioxidant-rich plant extracts as dietary food supplements. The aim of this study was to investigate the effect of an acute bout of sub maximal exercise on platelet count and differential response of platelet activation in trained and sedentary subjects and to observe if cocoa polyphenols reverse the effect of exercise on platelet function. The practical significance of this study was that many sedentary people engage in occasional strenuous exercise that may predispose them to risk of heart disease. Fasting blood samples were collected from 16 male subjects, pre and post 1-h cycling exercise at 70% of maximal aerobic power (VO2max) before and after consumption of cocoa or placebo. Agonist stimulated citrated whole blood was utilized for measuring platelet aggregation, adenosine triphosphate (ATP) release and platelet activation. Baseline platelet count (221 +/- 33 x 10(9)/L) and ATP release (1.4 +/- 0.6 nmol) increased significantly (P < 0.05) after exercise in all subjects. Baseline platelet numbers in the trained were higher (P < 0.05) than in the sedentary (235 +/- 37 vs. 208 +/- 34 x 10(9)/L), where as platelet activation in trained was lower (P < 0.05) than sedentary (51 +/- 6 vs. 59 +/- 5%). Seven days of cocoa polyphenol supplementation had little effect on any of the parameters measured. We conclude that trained subjects show decreased activation of stimulated platelets when compared to the sedentary subjects and short-term cocoa polyphenol supplementation did not decrease platelet activity in response to exercise independent of prior training status.

Thrombocyte aggregation, endothelial dysfunction and acute myocardial infarction

<zakljucak> Akutni infarkt miokarda u razvijenim i srednje razvijenim zemljama jedan je od najcescih uzroka mortaliteta i morbiditeta, pa poznavanje patofiziologije ateroskleroze i aterotromboze predstavlja najveci izazov savremenoj medicini. Najcesci uzrok AIM je ateroskleroza epikardnih koronarnih arterija sa posledicnom rupturom i/ili erozijom aterosklerotskog plaka, nastajanjem intrakoronarne tromboze i prekida cirkulacije arterijske krvi u predelu irigacije infarktne arterije. Sklonost ka aterosklerozi ne znaci po pravilu i sklonost ka trombozi, i obrnuto. Mnogobrojni faktori rizika od ishemijske bolesti srca modifikuju funkciju hemostaznog sistema, remete ravnotezu izmedju proagregatornih i antiagregatornih, prokoagulantnih i antikoagulantnih, profibrinolitickih i antifibrinolitickih mehanizama. Na taj nacin genetski uslovljena sklonost ka trombozi potencira se faktorima rizika, sto zajedno vodi ka aterotrombozi i akutnom koronarnom sindromu. Fizicko opterecenje je jedan od faktora rizika od ishemijske bolesti srca. Efekat zavisi od vrste opterecenja, duzine trajanja i stepena utreniranosti bolesnika. Umerena fizicka aktivnost kroz duzi vremenski period ima protektivni znacaj kod bolesnika sa ishemijskom bolescu srca, jer poboljsava funkciju endotela, smanjuje oksidativni stres na nivou endotela, smanjuje broj i aktivnost trombocita kao i aktivnost mnogih faktora koagulacije i na taj nacin smanjuje ucestalost ponovnih koronarnih dogadjaja. Nasuprot tome, akutna fizicka aktivnost dovodi do izrazenog prokoagulantnog stanja sto na terenu disfunkcije endotela i specificnosti hemostaznog sistema moze provocirati ponovnu koronarnu trombozu.

The effect of physical exercise on the daily rhythm of platelet aggregation and body temperature in horses

The goal of this study was to investigate the influence of physical activity on the daily rhythm of platelet aggregation and body temperature in horses. Blood samples from 12 Thoroughbred horses, six sedentary animals and six athletes (studied both before and after a period of inactivity) were collected at 4h intervals for 48h via an intravenous cannula inserted into the jugular vein. Body temperature was recorded every 4h for 48h with a rectal probe. Platelet aggregation was measured with an aggregometer. Collagen was used to test the aggregation of the plasma samples. Statistical analysis of the data was performed by one-way repeated-measures analysis of variance (ANOVA) and by single cosinor method. Cosinor analysis identified the periodic parameters and their acrophases (expressed in hours) during the 2 days of monitoring. On each single day, there was a highly significant effect of time in all the horses, with P values <0.05. Temperature rhythms were unaffected by exercise. Platelet aggregation in exercising horses differed from the sedentary horses, and this difference disappeared after a 2-week period of rest. The results could be interpreted as indicating that physical exercise has an influence on the daily rhythm of platelet aggregation in horses.

The effect of exercise on von Willebrand factor and ADAMTS-13 in individuals with type 1 and type 2B von Willebrand disease

BACKGROUND

The effect of exercise on von Willebrand factor (VWF) and ADAMTS-13 levels in individuals with von Willebrand disease (VWD) has never been reported.

OBJECTIVES

The aim was to quantify the effect of a standardized exercise protocol on individuals with type 1 and type 2B VWD.

PATIENTS/METHODS

Thirty individuals from three groups (10 controls, 11 with type 1 VWD and 9 with type 2B VWD) completed the Standard Bruce Protocol Treadmill Test. A bleeding questionnaire was administered and blood tests were performed pre- and immediately postexercise. The groups were well matched for age, gender and body mass index (BMI).

RESULTS

There was a correlation in all groups between the metabolic equivalents (METS) achieved and the degree of change of VWF and FVIII:C levels (P < 0.002, Pearson's correlation). There was a significant postexercise increase in VWF:Ag, VWF:RCo, FVIII:C and activated VWF levels in both the control group and in the type 2B VWD group, but not in the type 1 VWD group. Specific to the type 2B VWD group was an increase in the percentage of high molecular weight multimers (P = 0.022), a decrease in the mean platelet count compared with the other groups (P < 0.001) and an increase in the ADAMTS-13 level (P = 0.001).

CONCLUSIONS

There are significant differences in the effects of exercise on individuals with type 1 and type 2B VWD compared with controls. Further clinical studies are necessary to evaluate exercise as a therapeutic option in VWD.

Changes in the haemostatic system after thermoneutral and hyperthermic water immersion

Warm water bathing is a popular recreational activity and is frequently used in rehabilitation medicine. Although well tolerated in most cases, there are reports indicating an increased risk of thrombotic events after hot tub bathing. The effects of a 45 min thermoneutral bath followed by a 50 min bath with increasing water temperature (maximum 41 degrees C) until reaching a body core temperature of 39 degrees C on factors of blood coagulation and fibrinolysis were studied in eight healthy male volunteers. Blood was obtained after a 45-min resting period as control and after the thermoneutral and hyperthermic bath as well as after another 45 min recovery period at the end of the study. Hyperthermic immersion (HI) lead to a shortening of activated partial thromboplastin time (aPTT) (P < 0.05). Fibrinogen concentration decreased immediately after HI (P < 0.05) but increased during recovery (P < 0.05). Plasminogen activator inhibitor (PAI) activity decreased during HI (P < 0.05), D-dimer concentration was not found to change. Thrombocyte count increased (P < 0.05) during HI. The increases in tissue-type plasminogen activator concentration as well as leucocyte count during HI were due to haemoconcentration. Prothrombin time, PAI-activity and granulocyte count decreased during thermoneutral immersion (P < 0.05). Warm water bathing leads to haemoconcentration and minimal activation of coagulation. The PAI-1 activity is decreased. A marked risk for thrombotic or bleeding complications during warm water bathing in healthy males could not be ascertained.

Hemostatic responses to resistance training in patients with coronary artery disease

PURPOSE

This study was undertaken to evaluate changes in coagulation and fibrinolytic responses to an acute bout of resistance training in patients with coronary artery disease.

METHODS

Fourteen low-to-moderate risk men (mean age, 57.6 +/- 9 years; body mass index, 26.7 +/- 4.0 kg/m) with known coronary artery disease participated in this study. All subjects were recruited from the hospital's outpatient cardiac rehabilitation program and none were participating in a resistance training exercise program at the time. Using 8 different resistance training devices, each subject performed 1 set of 10 repetitions to volitional fatigue, resting 1 minute between sets. Blood samples (5 mL) were drawn preexercise, immediate postexercise, and 1 hour postexercise in the seated position. All values were corrected for plasma volume changes. Alterations in von Willebrand Factor antigen, tissue plasminogen activator antigen, and plasminogen activator inhibitor-1 activity were analyzed using repeated measures analysis of variance.

RESULTS

Although von Willebrand Factor antigen remained unchanged from preexercise values, tissue plasminogen activator antigen and plasminogen activator inhibitor-1 activity increased and decreased, respectively, in the immediate postexercise recovery period. Moreover, the latter reduction persisted at 1 hour postexercise.

CONCLUSION

An acute bout of resistance training improves fibrinolytic potential in men with coronary artery disease, without elevating thrombotic potential. These data support the safety of resistance training in this population when contemporary prescriptive guidelines are used.

Exercise training-induced changes in coagulation factors in older adults

The coagulation cascade plays a critical role in the development of cardiovascular disease (CVD). Elevated plasma prothrombin fragment 1 + 2 (F1 + 2) and factor VIII antigen (FVIII:Ag) levels have been associated with a hypercoagulable state, enhancing the risk for vascular thrombotic events. Aerobic training is known to reduce CVD risk, and an improved coagulation profile may contribute to this reduction.

PURPOSE

To analyze the effect of 6 months of standardized aerobic exercise training on resting F1 + 2 and FVIII:Ag levels in men and postmenopausal women aged 50-75 while accounting for several possibly confounding factors.

MATERIALS AND METHODS

Sedentary men (N=16) and women (N=31) underwent supervised aerobic training 3 d x wk(-1) for 6 months while maintaining the American Heart Association step 1 diet. Baseline and final testing included measurement of F1 + 2, FVIII:Ag, plasma lipoprotein-lipid levels, body composition, and VO2max.

RESULTS

When adjusted for baseline values and changes in diastolic blood pressure with training, F1 + 2 was found to decrease significantly with exercise training from 1.493 +/- 0.058 to 1.422 +/- 0.059 nM (P=0.014). FVIII:Ag levels were found to increase significantly with training when adjusted for baseline values, from 152.5 +/- 6.7% of standard at baseline to 156.0 +/- 6.1% of standard at final testing (P=0.005). Training-induced changes in coagulation markers were independent of changes in blood lipids, aerobic capacity, and body composition.

CONCLUSIONS

: These results indicate that endurance training has a significant impact on the coagulation cascade, reducing coagulation activity in the common pathway and thrombin formation at rest while increasing the activation potential of the intrinsic pathway.

Time course and mechanisms of mental stress-induced changes and their recovery: hematocrit, colloid osmotic pressure, whole blood viscosity, coagulation times, and hemodynamic activity

The mechanisms for stress-induced changes in hematocrit and blood viscosity are unclear. Twenty-two males completed experimental (30 min baseline, 10 min mental stress, 30 min recovery) and no-stress control conditions (70 min). Hemostatic and hemodynamic activity were measured throughout. Hematocrit, colloid osmotic pressure, and blood viscosity displayed parallel patterns: a progressive increase with stress, followed by a gradual recovery. Correlational and covariance analyses indicated that the increase in hematocrit may be mediated by arterial pressure whereas recovery may be mediated by colloid osmotic pressure. Analyses also indicated that acute changes in blood viscosity may depend on hematocrit. These data suggest that stress disturbs hematocrit, colloid osmotic pressure, and blood viscosity through arterial pressure. Poststress, elevated colloid osmotic pressure may drive its own recovery and that of hematocrit and blood viscosity.