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This Position Stand provides guidance on fluid replacement to sustain appropriate hydration of individuals performing physical activity. The goal of prehydrating is to start the activity euhydrated and with normal plasma electrolyte levels. Prehydrating with beverages, in addition to normal meals and fluid intake, should be initiated when needed at least(More)
To test the hypothesis that progestin-mediated increases in resting core temperature and the core temperature threshold for sweating onset are counteracted by estrogen, we studied eight women (24 +/- 2 yr) at 27 degrees C rest, during 20 min of passive heating (35 degrees C), and during 40 min of exercise at 35 degrees C. Subjects were tested four times,(More)
The time and frequency domain components of heart rate variability have been used to assess prognosis in patients with different types of heart disease. However, the effect of habitual exercise, which influences baseline parasympathetic tone, on heart rate variability has not been fully evaluated. To determine the effect of chronic exercise on heart rate(More)
The relationship of 11 measures of trunk and lower limb flexibility to the economy of treadmill walking and jogging as measured by steady-state oxygen consumption (VO2) was studied. Subjects (38 women, 62 men, aged 20-62 years) were tested at six speeds between 53.6 and 187.7 m/min. By combining scores from all flexibility tests, and beginning at speeds of(More)
To test the hypothesis that the inhibitory action of central blood volume expansion on thirst and renal fluid regulation is attenuated with aging, we monitored the drinking and renal responses of dehydrated older (70 +/- 2 yr, n = 6) and younger (24 +/- 1 yr, n = 6) subjects during 195 min of head-out water immersion (HOI), which shifts blood centrally and(More)
To evaluate criteria frequently used to designate an exercise test as maximal, 33 men and 18 women completed progressive incremental cycle ergometry to exhaustion with direct measurement of oxygen consumption (VO2). On a separate day, subjects exercised at 115% of the maximal work rate attained in the first test following a 5-minute warm-up. If VO2 exceeded(More)
We hypothesized that orthostatic tolerance is higher in young, healthy black compared with white women. To determine orthostatic tolerance, 22 women (11 black and 11 white) underwent graded lower body negative pressure to presyncope. We measured blood pressure, heart rate, and R-R interval (ECG) continuously at baseline and through all of the levels of(More)
OBJECTIVES The accurate noninvasive assessment of preload in emergency department (ED) patients remains elusive. Point-of-care ultrasound (US) imaging, particularly evaluation of the inferior vena cava (IVC), has been shown to be qualitatively helpful. Doppler and tissue Doppler are now routinely available on ED US equipment, but few studies have looked at(More)
To determine if estrogen upregulates osmotic secretion of arginine vasopressin (AVP) and alters body water balance, we infused hypertonic (3% NaCl) saline in 6 women (68 +/- 3 yr) after 14 days of 17 beta-estradiol (transdermal patch, approximately 0.1 mg/day, E2) and placebo (control) administration. Hypertonic saline was infused at 0.1 ml.kg-1.min-1 for(More)
To test the hypotheses that plasma volume (PV) expansion 24 h after intense exercise is associated with reduced transcapillary escape rate of albumin (TERalb) and that local changes in transcapillary forces in the previously active tissues favor retention of protein in the vascular space, we measured PV, TERalb, plasma colloid osmotic pressure (COPp),(More)