Medicine and science in sports and exercise
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Med Sci Sports Exerc · Dec 1995
Comparative StudyThe prevalence and significance of post-exercise (postural) hypotension in ultramarathon runners.
A consistent finding in exercise-associated collapse is a marked postural fall in the systolic blood pressure associated with a tachycardia. The prevalence and significance of these post-exercise (postural) changes in blood pressure among noncollapsed ultradistance athletes has not been well documented. The aim of this study was to compare pre- and post-race changes in systolic and diastolic blood pressures with changes in body weight and plasma volume and with symptoms of post-exercise hypotension, including the effects of posture, among a group of 31 runners competing in an 80-km footrace. ⋯ Asymptomatic postural hypotension defined as a fall in systolic blood pressure of greater than 20 mm Hg from the supine to the erect position without syncopal symptoms was present in two runners (7%) before the race and in 21 runners (68%) afterward. The degree of postural variation in systolic blood pressure was unrelated to changes in body weight or a fall in plasma volume. We conclude that (i) all runners were dehydrated by the race activity with a range of 1% to 7% and an average of 4.6%; (ii) asymptomatic post-exercise (postural) hypotension developed in the majority (68%) of ultramarathon runners in this study; (iii) the post-exercise hypotension is likely of multifactorial origin and is not entirely related to whole body dehydration or a reduction in plasma volume; and (iv) despite marked levels of dehydration among our sample of runners, their cardiovascular status in the supine position was not greatly compromised.
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Relatively few studies have assessed the prospective relationship of sedentary lifestyle and coronary heart disease (CHD) in women. We performed a nested case-control study, identifying 50 cases of acute CHD in women and 150 age-matched controls. Risk factors including sedentary lifestyle, cigarette smoking, hypertension, diabetes mellitus, total, and HDL cholesterol levels had been previously determined in this cohort using household survey techniques. ⋯ S. born. This study suggests that sedentary lifestyle may be an independent risk factor for CHD in women, but its results are open to several contradictory interpretations. Further studies to investigate the prospective relationship of sedentary lifestyle and the risk of CHD in women are needed.
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Med Sci Sports Exerc · Jan 1995
Case ReportsAcute exertional anterior compartment syndrome in an adolescent female.
Acute compartment syndromes usually occur as a complication of major trauma. While the chronic exertional anterior tibial compartment syndrome is well described in the sports medicine literature, reports of acute tibial compartment syndromes due to physical exertion, or repetitive microtrauma, are rare. The case of an adolescent female who developed an acute anterior compartment syndrome from running in a soccer game is described in this report. ⋯ Whereas the chronic exertional anterior compartment syndrome is characterized by pain that diminishes with the cessation of exercise, the onset of the acute exertional anterior compartment syndrome is heralded by pain that continues, or increases, after exercise has stopped. Compartment pressure measurement confirms the clinical diagnosis and helps guide treatment. True compartment syndromes require urgent fasciotomy.
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Med Sci Sports Exerc · Jan 1995
Comparative StudyEnergy aspects for elastic and viscous shoe soles and playing surfaces.
The purpose of this project was to determine the effect of changes in stiffness and viscosity of the foot ground interface on the work performed during locomotion. The estimation of the work during locomotion was derived from a mathematical two segment model, representing the foot and the rest of the body. ⋯ The estimations of the work required during a step cycle is generally higher for softer than for harder springs and for low damping compared with high damping. The model calculations demonstrate that specific combinations of material properties may be advantageous or disadvantageous from an energy point of view.
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Med Sci Sports Exerc · Dec 1994
ReviewAcquisition and maintenance of the simplest motor skill: investigation of CNS mechanisms.
The spinal stretch reflex (SSR), or tendon jerk, is the simplest behavior of the vertebrate nervous system. It is mediated primarily by a wholly spinal, two-neuron pathway. Recent studies from several laboratories have shown that primates, human and nonhuman, can gradually increase or decrease the size of the SSR when reward depends on such change. ⋯ Results to date indicate that modifications are present at several places in the spinal cord. Current clinical studies are investigating the use of spinal cord adaptive plasticity as a basis for a new therapeutic approach to spasticity and other forms of abnormal spinal reflex function that result from spinal cord injury, stroke, or other neurological disorders. In the future, understanding of spinal reflex plasticity may lead to development of improved training methods for a variety of motor skills.