Medicine and science in sports and exercise
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Med Sci Sports Exerc · Apr 2013
Exercise-associated hyponatremia and hydration status in 161-km ultramarathoners.
This work combines and reanalyzes 5 yr of exercise-associated hyponatremia (EAH) research at 161-km ultramarathons in northern California with primary purposes to define the relationship between postrace blood sodium concentration ([Na]) and change in body weight; to examine the interactions among EAH incidence, ambient temperature, and hydration state; and to explore the effect of hydration status on performance. ⋯ EAH incidence can be high in 161-km ultramarathons in northern California. In this environment, EAH is more common with dehydration than overhydration and is more common in hotter ambient temperature conditions. Because weight loss >3% does not seem to have an adverse effect on performance, excessive sodium supplementation and aggressive fluid ingestion beyond the dictates of thirst are ill advised.
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Med Sci Sports Exerc · Feb 2013
Autonomic function and exercise performance in elite athletes with cervical spinal cord injury.
"Complete" cervical spinal cord injury (SCI) is commonly believed to cause the decentralization of spinal sympathetic circuits and a consequent inability to meet the hemodynamic demands of exercise. Recently, however, we have noticed that athletes with motor complete cervical SCI exhibit an exercise-induced tachycardia that appears to be at odds with the known effects of sympathetic decentralization. ⋯ All participants exhibited partial preservation of descending sympathetic control. We also found that the degree of remaining SSR, but not IWRF classification, was strongly correlated with indices of exercise performance. The findings suggest that the degree of remaining sympathetic control is an important determinant of exercise performance in athletes with cervical SCI.
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Med Sci Sports Exerc · Nov 2012
Exercise performance over the menstrual cycle in temperate and hot, humid conditions.
This study investigated the effects of the menstrual cycle on prolonged exercise performance both in temperate (20°C, 45% relative humidity) and hot, humid (32°C, 60% relative humidity) conditions. ⋯ In temperate conditions, no changes in prolonged exercise performance were found over the menstrual cycle, whereas in hot, humid conditions, performance was decreased during the luteal phase. The combination of both exercise and heat stress with the elevated luteal phase Tc at the onset of exercise resulted in physiological and perceptual changes and a greater thermosensitivity, which may explain the decrease in performance.
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Med Sci Sports Exerc · Oct 2012
Randomized Controlled TrialEffects of exercise therapy on cardiorespiratory fitness in patients with schizophrenia.
Increased mortality in schizophrenia is caused largely by coronary heart disease (CHD). Low cardiorespiratory fitness (CRF) is a key factor for CHD mortality. We compared CRF in patients with schizophrenia to CRF of matched healthy controls and reference values. Also, we examined the effects of exercise therapy on CRF in patients with schizophrenia and in controls. ⋯ Patients had lower CRF levels compared with controls and reference values. Exercise therapy increased VO(2peak) and W(peak) in patients and controls. VO(2peak) and W(peak) decreased in nonexercising patients.