Syncope with abrupt termination of exercise

Article Abstract:

Syncope is a temporary loss of consciousness due to diminished blood supply to the brain. It rarely affects athletes when they have finished a session of strenuous exercise. A 34-year-old man who jogged 20 miles or more per week experienced several episodes of syncope after jogging or playing racquet ball. The results of his EKG and cardiac stress testing were normal. Only when the patient wore a Holter monitor during his normal exercise regimen was it possible to measure the response of his heart. Upon discontinuing exercise, the patient suffered a syncopal episode during which there was rapid progression from sinus tachycardia (rapid heartbeat) to sinus bradycardia (abnormally slow heartbeat), with a rate of 40 beats per minute. Blood pressure became abnormally low (hypotension). In addition, there were several sinus pauses, or interruptions in the functioning of the sinus node, which acts as the natural pacemaker of the heart. Because of the patient's recurrent and severe symptoms and his unwillingness to forego vigorous exercise, a pacemaker was implanted. The authors suggest that the syncope may be a result of the fact that during vigorous exercises, the blood vessels serving the body muscles dilate to accommodate the increased blood flow. Reduction in venous return (blood returning to the heart), accompanied by excessive heart stimulation during exercise, causes a ventricular squeeze in the heart that produces bradycardia and hypotension. When syncope occurs following exercise, patients should be advised to avoid maximal physical activity. Bradycardia may be treated with atropine. In some cases, a pacemaker may become necessary, but this should be avoided and used only as a last resort.

Case studies, Causes of, Bradycardia, Hypotension, Loss of consciousness, Unconsciousness

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Exercise and its interaction with genetic influences in the determination of bone mineral density

Article Abstract:

Reduced bone density is an important contributing factor to bone fractures in the elderly. Bone density in adulthood is directly related to the peak bone mass achieved during adolescence and subsequent bone loss. During menopause the ovaries stop making estrogen, and sex hormone deficiency is one of the most important factors in bone loss. During this period, bone density is lost at a rate of 1 to 2 percent per year, but the rate of bone loss decreases 5 to 10 years after menopause. Perhaps the best way to prevent osteoporosis is to maintain good bone density prior to menopause. Genetic factors, dietary calcium and physical activity have all been reported to affect bone mass. Physical fitness, muscle mass and bone density all have genetic determinants. In men, calcium intake appears to be related to bone density, but this has not been proven for women. While previous studies have reported that calcium supplements do not affect bone density in women, more recent studies have reported that calcium supplements prevent bone loss in women who are more than six years postmenopausal. Several studies have reported that individuals who are physically fit and strong have greater bone density. One study reported that a 40-week exercise program was effective in increasing lower spine bone density in postmenopausal women. However, it has been reported that excessive physical exercise that leads to estrogen deficiency in young females has negative effects on bone mass that may not be reversible. It seems reasonable to recommend regular weight-bearing exercises as part of a program to prevent osteoporosis. (Consumer Summary produced by Reliance Medical Information, Inc.)

Bones, Bone density, Calcium (Nutrient), Calcium, Dietary

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Syncope and orthostatic hypotension

Article Abstract:

Orthostatic hypotension is a drop in blood pressure that occurs when a person assumes a standing position. It has been shown to cause syncope, or fainting, in 4 to 9 percent of adults and 20 percent of children. The relation between orthostatic hypotension and syncope remains unclear because: (1) the appropriate type and methods of blood pressure measurement and significance of blood pressure change have not been determined; (2) the relation between orthostatic hypotension and a specific attack of syncope is difficult to establish; and (3) the relevance of an abnormal drop in blood pressure that causes no adverse symptoms is questionable. The time-related changes in blood pressure, prevalence of orthostatic hypotension, and relation of orthostatic hypotension to recurrence of syncope were assessed in 223 patients with a history of syncope. Orthostatic hypotension, which was defined as a drop in blood pressure of 20 millimeters of mercury (mm Hg) or more, was detected in 69 of 223 patients and occurred, on average, within 2.4 minutes of standing. The rate of recurrent syncope and dizziness was lower among patients with orthostatic hypotension, compared to patients with lesser declines in blood pressure. Thus, orthostatic hypotension is common among patients with syncope, usually developing within two minutes of standing. The relation between orthostatic hypotension and recurrence of syncope requires further study. (Consumer Summary produced by Reliance Medical Information, Inc.)

Abnormalities, Complications and side effects, Risk factors, Blood pressure, Hypotension, Orthostatic, Orthostatic hypotension

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