Effects of strenuous exercise on haemostasis

OBJECTIVES: To review the effects of exercise on haemostasis and examine the possible clinical sequelae of these changes. METHODS: The search strategy included articles from 1966 to August 2002 using Medline and SportDiscus databases, and cross referencing the bibliographies of relevant papers. RESULTS: Exercise results in activation of both the coagulation and fibrinolytic cascades, as shown by a reduction in whole blood clotting time and activated partial thromboplastin time, an increase in the activity of several components of the cascades, and an increase in fibrin degradation products. In vitro tests suggest that coagulation remains activated after fibrinolysis has returned to baseline levels. CONCLUSIONS: Both the coagulation and fibrinolytic cascades are stimulated by strenuous exercise, but the temporal relation between the two and its clinical significance remains to be clarified. Doctors and athletes should be aware of the haemostatic changes induced by exercise, and further work is needed to clarify the possible role of these changes in sudden cardiac death.     

Effect of warm-up on metabolic responses to strenuous exercise.

Aerobic and anaerobic energy transformations were measured in two trained runners during 90-sec treadmill runs at 23.6 km/hr (2% grade). The runs were preceded by rest or either of two warm-ups: 1) 15-min run at 10 km/hr, or 2) 15-min run at 10 km/hr followed by 3-min standing. Compared with runs without warm-up, during the third half minute of runs following both types of warm-up 11% greater heart rates (HR), 8% greater oxygen consumption (Vo2), and unchanged ventilation were recorded. The rate constant of the approach of Vo2 to O2 in the first minute of work was unaffected by warm-up. Runs following either warm-up resulted in 25% lower lactate production; during these runs 3 to 4 degrees C higher gastrocnemius muscle temperatures (Tm) were maintained. The differences in HR, Vo2, and Tm continued throughout exhausting 5-min runs at 20.9 km/hr (2% grade). An elevated muscle temperature may therefore be requisite for the maximal aerobic response to a short exhausting run.     

Effects of strenuous exercise on myocardial blood flow

Myocardial blood flow is the major determinant of oxygen delivery to the myocardium, since oxygen extraction by the myocardium is near maximum in the resting state. Regulation of flow during exercise depends on local metabolic factors and, to a small extent, on autonomic tone. Maximum flow of 5-6 times resting has been measured in reactive hyperemia experiments. In strenuous exercise, myocardial oxygen delivery appears to be adequate and flow reserve seems capable of handling the increased oxygen demand. No evidence of myocardial failure in normal hearts due to excess exercise has been presented. However, pulmonary hemorrhages found in horses after strenuous racing may be due to inadequate cardiac performance at maximal capacity. In humans, severe limitations to myocardial blood flow are imposed by coronary artery disease and by cardiac hypertrophy. In both cases regional myocardial ischemia may occur during the increased oxygen demands imposed by strenuous exercise. Individuals with coronary disease or cardiac hypertrophy are at risk for myocardial ischemia during exercise. Detection of myocardial blood flow abnormalities and ischemia during exercise has become an important goal in cardiac diagnosis. Prevention of serious or lethal consequence of strenuous exercise depends on a better understanding of the factors that regulate myocardial blood flow during ischemia.     

Effect of strenuous exercise on blood monocytes and their relation to coagulation

Changes were explored in the behavior of circulating monocytes and their potential association with the activation of the coagulation system as assessed following strenuous exercise. Twelve men and nine women from the Norwegian national cross country skiing team and 19 men and six women from a level just below that of the national team were studied before and after ski race competition. Mononuclear cells were isolated after incubation of heparinized blood with lipopolysaccharides (LPS; 3 ng.ml-1) for 2 h. After a 50 km race for men, the specific thromboplastin activity of the stimulated monocytes rose from 3.5 x 10(-3)/10(6) cells to 21.4 x 10(-3)/10(6) cells. This probably reflects the mobilization of a new population of monocytes that are more sensitive to such stimuli. Resting top-athlete skiers had monocytes which were significantly less responsive to the LPS stimulus compared to nontrained people. There was an inverse correlation of plasma factor VII and the monocyte responsiveness to in vitro stimulation (r = 0.814; P less than 0.002) from blood drawn after a race. Furthermore, factor VII was significantly reduced after a 50 km race, and a modest decline in the fibrinogen level was also observed (P less than 0.05). It is concluded that endurance ski racing causes white cell mobilization and more active white cells that may induce activation of the coagulation system and account for the involvement of factor VII and fibrinogen.     

Oxidation of lactate in rats after short-term strenuous exercise

Oxidation of lactate and glucose was investigated in rats after short-term strenuous running to exhaustion at a speed of 80-110 m.min-1, lasting about 100 sec. Immediately after the exercise, 4 microCi of [U-14C]lactate (LA and AR) or 9.4 microCi of [U-14C]glucose (GL) was injected into the aorta through an indwelling catheter. In AR, the rats ran at a speed of 25 m.min-1 for 20 min after injection of [U-14C]lactate. Expired gas was collected by a bottomless metabolism chamber while the rats were on the treadmill for 120 min. Blood lactate concentration tended to decrease faster in AR than in LA. Peak evolution of 14CO2 expiration occurred at 12.5 min recovery in LA, 7.5 min of recovery in AR, and 35 min of recovery in GL. Cumulative percent recovery of 14C as 14CO2 was 48.5% +/- 2.8% in LA, 74.0% +/- 2.9% in AR, and 18.6% +/- 1.6% (mean +/- SE) in GL. Significant differences were found in these rates between groups (P less than 0.01). It was suggested that a great deal of lactate was oxidized directly, not after conversion to glucose in rats after short-term strenuous exercise to exhaustion and mild exercise following strenuous exercise (active recovery) enhanced lactate oxidation.     

Cardiac troponin T release after prolonged strenuous exercise

Over the past 2 decades, there has been a large interest in cardiac troponin T (cTnT) elevations, which are often seen following endurance sport events. There have been many reports on this topic, although sometimes with different approaches. We reviewed the available literature on cTnT elevations after prolonged strenuous exercise and discovered profound differences in the percentage of subjects reported to have elevated cTnT concentrations. This could partly be attributed to differences in immunoassay characteristics, such as cross-reactivity with skeletal troponin T, and the use of different cut-off values used in the different studies. The elevations were transient, with levels decreasing to pre-event concentrations within 24-48 hours. This might be explained by the relatively short half-life of cTnT, or water imbalance during and after the event. The release mechanism of cTnT, as well as the long-term positive or negative effects, remains unclear. Future research should therefore be aimed at clarifying the release mechanism of cTnT. Furthermore, the benefits and the possible long-term negative aspects of prolonged exercise should be evaluated.     

Biochemical changes as a result of prolonged strenuous exercise

OBJECTIVE: To briefly review biochemical changes that may result from prolonged strenuous exercise and to relate these changes to health risk. METHODS: Medline and Sports Discus databases were searched for relevant articles. Additional articles were found using cross referencing and the authors' knowledge of the subject area. RESULTS: Prolonged strenuous exercise may result in a series of biochemical changes that are of concern from a health point of view. Generally, these changes are benign, but some, especially hyponatraemia, are potentially life threatening occurrences. CONCLUSION: Doctors and athletes should be aware of the potentially adverse biochemical changes, especially hyponatraemia, that may result from prolonged strenuous exercise.     

CT demonstration of spinal epidural emphysema after strenuous exercise

We report a case of spinal epidural emphysema after strenuous exercise. The emphysema was without clinical signs and disappeared after 2 weeks.     

HIV-seroconversion following sexual abuse

Transkei is a poverty stricken former black homeland, now a part of the Eastern Cape Province. Unemployment and the incidental violence are very high. Women are mainly responsible for bringing up their children. Single parenting is also common in this community. Sexual abuse of children is selected to be under-reported. This reports the case of a 13-year-old girl who was raped twice within three months and brought to the Sinawe Centre of the Nelson Mandela Academic Hospital. Failure to adhere to post exposure prophylaxis (PEP) has undermined the implementation of antiretroviral roll out programme by the government. The history, physical examination and laboratory investigations of this case are given. Preventive steps are suggested.     

Transient cardiac left ventricular diastolic dysfunction following strenuous exercise

Abstract The long term clinical significance of exercise-induced cardiac fatigue has not been clearly addressed. The aim of this study was to assess the effects of repetitive competitive high altitude running on left ventricular performance. Eleven athletes were studied before and after two high altitude races in two consecutive years. On both occasions 12-lead elettrocardiography (ECG) as well as Doppler echocardiography were performed 24 hours before, shortly after (within 30 min) and 24 hours after the end of the race. Measurements included ejection fraction, early (E) and late (A) transmitral inflow velocities, their ratio (E/A) and percent atrial contribution (AC). Similar studies were performed in 11 age- and sex-matched control subjects at baseline and following a maximal exercise test. Ejection fraction remained stable in both. Conversely, Doppler E/A ratio significantly decreased in atletes early after the race from 1.9±0.1 to 1.3±0.1 (p<0.05) for the first race and from 1.7±0.1 to 1.4±0.1 (p<0.05) for the second race. The decrease was mainly due to a reduction in E (p<0.05), since A was not modified. AC increased from 20%±3% to 28%±5% (p<0.05) and from 21%±3% to 26%±6% (p<0.05), respectively. All parameters returned to baseline at a 24-hour control. Compared to controls, all athletes had significantly higher resting E and A velocities and lower E/A ratio and AC to ventricular filling shortly after exercising. All parameters returned to baseline at the 24-hour controls. These findings are consistent with previous studies reporting transient cardiac fatigue following strenuous exercise. However, the functional effects of these changes do not seem to interfere with cardiac function and athletic performance in both the short term and medium-long term.     

Caffeine improves cognitive performance after strenuous physical exercise.

The effects of three carbohydrate electrolyte solutions (CES) containing different amounts of caffeine on cognitive function and the combined effects of these drinks and exercise on cognitive functions were investigated in a double-blind, cross-over study. On five separate occasions, fifteen endurance trained male athletes (23.3 years) received water placebo, CES placebo (68.8 g/l), and three CES drinks containing low, medium and high dosages of caffeine (150, 225 and 320 mg/l). Each occasion, 8 ml/kg of the drink was consumed before -- and 6 ml/kg of the drink was consumed during an all-out 1 hour time trial on a bicycle ergometer. Cognitive (attentional, psychomotor, and memory) tests were carried out immediately before and immediately after exercise. Before exercise, long term memory was improved by CES plus low dose caffeine compared to both placebos. Immediately after exercise, all cognitive functions were improved by CES plus low- and medium-dose caffeine compared to placebo. These results comprise the first practical demonstration of the cognition improving effects of low amounts of caffeine in CES after strenuous physical exercise.     

Military sexual trauma: violence and sexual abuse

Military sexual trauma includes sexual assault and sexual harassment in military settings by intimate partners and active duty personnel. Such violence triggers a syndrome of episodic, clustered, psychological and physiological symptoms that may be fatal. Despite its pervasiveness, many clinicians fail to recognize as many as 95% of cases among veterans and active duty personnel. Many victims receive inadequate medical treatment or education. They face a decreased quality of life, high morbidity and mortality rates, and economic losses. Their children may also be at risk for abuse. In many settings, clinicians may not realize the high prevalence of this military sexual abuse among veterans and active duty personnel. Clinicians should understand the clinical manifestations, to detect abuse early, to treat it appropriately, and to minimize sequelae.     

Pulmonary hemodynamics during a strenuous intermittent exercise in healthy subjects

PURPOSE: It has been suggested that an intermittent work exercise test (IWET) is as efficient but better tolerated than continuous exercise for rehabilitation. Although systemic and pulmonary cardiovascular adjustments have been investigated for continuous exercise, it has not been done for IWET with exercise bouts near maximal work rate. METHODS: In seven healthy subjects, the pulmonary hemodynamics have been studied by the aid of heart catheterization during a strenuous 30-min bicycle IWET where a 4-min work set at the first ventilatory threshold (VT1) alternated with a 1-min work set at the second ventilatory threshold (VT2). RESULTS: During the IWET, cardiac output increased then remained stable with decreasing stroke volume and increasing heart rate, which became near maximal at the end of the test. Mean pulmonary arterial pressure increased from rest to the fifth minute of exercise and decreased significantly thereafter (P<0.01). An identical evolution was observed for mean systemic arterial pressure (SAP). CONCLUSION: Pulmonary hemodynamics adapt well in healthy subjects during a strenuous IWET despite the performance of exercise bouts of near maximal intensity.     

Genital findings in boys suspected for sexual abuse

Injuries in the genital region of boys are mostly caused by accidents. In this study, three cases of child abuse and one case suspicious for child abuse but explainable by a congenital undiscovered malformation are presented. Injuries or findings in the genital region are especially suspicious for child abuse, including sexual abuse. Because of the possible misinterpretation and the consequences of a false confirmation of a child abuse, an interdisciplinary cooperation between pediatrics, forensic experts, and pediatric urologist should be carried out in doubtful cases.     

Changes in urinary zinc and copper with strenuous physical exercise

BACKGROUND: Air rescue trainees in the Japan Air Self Defense Force participate in a curriculum that includes 24 wk of strenuous physical training. The trace minerals zinc and copper are directly involved in many physiologic processes that are altered by physical exercise of this sort. It has also been demonstrated that urinary excretion of catecholamines (adrenaline and noradrenaline) increases during both mental work and physical exercise. HYPOTHESIS: Air rescue trainees will exhibit changes in trace mineral excretion and catecholamine levels that vary with the type of training undertaken. METHODS: The levels of urinary zinc (Zn), copper (Cu), noradrenaline (NAd), and adrenaline (Ad) were determined in 11 air rescue trainees before and after daily training sessions for consecutive 3- or 4-d periods during four phases of the curriculum, as follows: control (Cont), classroom instruction without physical exercise; preliminary (Prelim), daily exercise sessions for increased physical strength; basic (Basic), a combination of lectures and demanding physical exercise; and simulated mountain rescue (Sim). RESULTS: The mean urinary concentrations of Zn and Cu increased significantly after sessions with physical exercise (Prelim, Basic, and Sim), but remained unchanged for Cont. The NAd levels also increased significantly after training with physical exercise. In contrast, Ad levels increased significantly after sessions in all phases, both with and without physical exercise. CONCLUSIONS: The urinary levels of Zn, Cu, NAd, and Ad rose with strenuous exertion, whereas only Ad responded to both physical and mental tasking.     

Inadequate cerebral oxygen delivery and central fatigue during strenuous exercise

Under resting conditions, the brain is protected against hypoxia because cerebral blood flow increases when the arterial oxygen tension becomes low. However, during strenuous exercise, hyperventilation lowers the arterial carbon dioxide tension and blunts the increase in cerebral blood flow, which can lead to an inadequate oxygen delivery to the brain and contribute to the development of fatigue.     

Activation and disturbance of blood haemostasis following strenuous physical exercise.

Physical exercise activates blood coagulation and enhances fibrinolytic activity. To investigate whether these activations of blood coagulation and fibrinolysis are balanced post-exercise and during the period of recovery, 11 moderately active young men were examined immediately after a standardised cycle ergometer test and during the 24 h period of recovery. Blood samples were obtained at rest, immediately after exercise, and 2, 6 and 24 h after exercise. All post-exercise values were corrected for any change in plasma volume. Exercise induced a significant increase in factor VIII activity and this occurred with a significant shortening of activated partial thromboplastin time. A concomitant enhancement of tissue plasminogen activity resulted in significant increases in tissue plasminogen activity antigen and total fibrin/fibrinogen degradation products, and a significant decrease in tissue plasminogen activator inhibitor-1 activity. Increases in coagulation and fibrinolytic activity changed in parallel during exercise. However, during recovery, while the increase in factor VIII activity post-exercise persisted 2 and 6 h into recovery, fibrinolytic activity demonstrated a sharp fall. It is concluded that whereas the enhanced fibrinolytic activity during exercise appears to counterbalance the increase in blood coagulability, this haemostatic balance is not maintained during recovery. This perturbed blood haemostasis could constitute an enhanced risk for coronary artery thrombosis and may contribute to exercise-related cardiovascular events.