Role of cerebrospinal fluid [H+] in ventilatory deacclimatization from chronic hypoxia.

Once ventilatory acclimatization begins in sea level residents sojourning at high altitude, abrupt restoration of normal oxygen tensions will not restore ventilation to normal. We have investigated the role of cerebrospinal fluid (CSF) [H(+)] in this sustained hyperventilation by measuring CSF acid-base status in seven men (lumbar) and five ponies (cisternal) in normoxia, first at sea level and then periodically over 13-24 h of "deacclimatization" after 3-5 d in hypoxia (P(B) = 440 mm Hg). After 1 h deacclimatization, hyperventilation continued at a level only slightly less than that obtained in chronic hypoxia (+1-2 mm Hg Pa(CO2)), whereas CSF pH was either equal (in man) or alkaline (in pony, +0.02, P < 0.01) to sea level values. Between 1 and 12-13 h deacclimatization in all humans and ponies Va fell progressively (Pa(CO2) increased 4-7 mm Hg) and CSF pH became increasingly more acid (-0.02 to -0.05, P < 0.01). Between 12 and 24 h of normoxic deacclimatization in ponies, Pa(CO2) rose further toward normal, coincident with an increasing acidity in CSF (-0.02 pH). Similar negative correlations were found between changes in arterial pH and Va throughout normoxic deacclimatization. We conclude that [H(+)] in the lumbar or cisternal CSF is not the mediator of the continued hyperventilation and its gradual dissipation with time during normoxic deacclimatization from chronic hypoxia. These negative relationships of Va to CSF [H(+)] in normoxia are analogous to those previously shown during acclimatization to hypoxia.

Total cholesterol and HDL-cholesterol changes during acute, moderate-intensity exercise in men and women.

Chronic endurance exercise training has been associated with decreased levels of total cholesterol and increased HDL-cholesterol. To our knowledge rapid changes in cholesterol and HDL-cholesterol during acute exercise have not been described under controlled conditions. We studied 28 subjects (14 males and 14 females) during bicycle exercise for 40 min at a work intensity of 55% of their maximal oxygen consumption. Total and HDL-cholesterol levels were measured (and LDL-cholesterol calculated) at rest, 10, 20, 30, and 40 min of exercise, and 15 min postexercise. There was a significant (p less than 0.001) increase in HDL-cholesterol levels at 10 min of exercise (58.8 +/- 13.9 mg/dl, mean +/- SD) above rest (53.1 +/- 13.4 mg/dl) for all subjects. This increase persisted (p less than 0.001) at all time points throughout the exercise session, but declined by 15 min postexercise. There was a small, insignificant decline in LDL-cholesterol. It is concluded that apparent favorable changes in lipoprotein patterns occur acutely, and are sustained during short-term, moderate intensity exercise. Analyses of these changes appears necessary if the biochemical mechanisms which underlie these metabolic alterations are to be elucidated.

Cardiovascular response to static contraction in borderline hypertension.

Nine young males with borderline hypertension (BH) (mean age +/- SD, 25 +/- 5 yr) and 13 young male normotensive controls (NT) (24 +/- 3 yr) were studied to determine their cardiovascular responses to small and large muscle static contractions. The subjects performed one-arm handgrip and two-leg extension in a randomly assigned order for 3 min at 30% of maximal voluntary contraction. Mean intra-arterial blood pressure (MABP), heart rate (HR), and tension were measured throughout the contractions. Borderline hypertensive patients had a higher MABP at rest (p less than 0.005) and at the end of both types of static contractions (p less than 0.05). The average increases in MABP from rest to the end of exercise (delta MABP) were slightly greater for the BH patients (6 mmHg), but these differences were not significant (p greater than 0.1). However, a greater percentage of BH patients were hyperreactive to handgrip (delta BP greater than 35 mmHg) and leg extension (delta BP greater than 40 mmHg) when compared to controls. These data indicate that, in general, young men with borderline hypertension demonstrate normal cardiovascular regulation in response to static contraction, but that a portion of this population may be hyperreactive to this type of circulatory stress.

Clinical guidelines for exercise training.

Exercise training may be useful for a variety of patients with and without established cardiovascular disease. The degree to which a patient participates in a prescribed exercise program depends strongly on initial motivation. The primary care physician can provide appropriate reinforcement with careful explanation of the effects of exercise on cardiovascular and metabolic function. Exercise programs may be combined effectively with other life-style adjustments, including weight loss, blood pressure control, and discontinuation of smoking. As a single intervention factor, exercise cannot prevent the evolution of cardiovascular disease in multiple-risk patients. Exercise is best used in combination with a program of comprehensive cardiovascular risk factor modification.

Dietary fiber and coronary artery disease.

Ischemic coronary disease remains the leading cause of death in the United States, and exerts a tremendous cost burden to the health care system. Hypercholesterolemia has been shown to be one of the major risk factors of artherosclerosis, which plays an important role in the pathogenesis of coronary artery disease (CAD). Over the past 3 decades, a variety of epidemiological, animal studies and human (clinical) trials have demonstrated the preventive and therapeutic benefits of dietary fibers on hypercholesterolemia and the reduction of mortality rate from CAD. To review the data, hopefully this article can draw more public attention to dietary fibers given their beneficial effects and relatively low side-effect profile. Diet modification should be the initial approach to the clinical management of hypercholesterolemia.

Heat Injury in Runners.

Physicians who are involved in warm-weather road races should familiarize themselves with the clinical syndromes of heat injury and develop a good plan for identification and immediate management of heat casualties.

Osteitis Pubis in Sports Activities.

Shear forces transmitted to the pubic symphysis in running and kicking sports may produce osteitis pubis. It could be confused with muscle strain, inguinal hernia, prostatitis, orchitis, or urolithiasis.

Impact of a body-mind treatment component on alcoholic inpatients.

1. A group of alcoholic patients who were treated with a physical fitness program as an adjunct to the usual program showed significantly less craving for alcohol than members in the standard treatment group. 2. The group treated with physical fitness as well as therapy saw themselves as having more internal locus of control and being less controlled by powerful others. 3. Nurses are the hospital professionals most likely to be involved with important roles in exercise programs with alcoholic patients.

Exertional heatstroke in novice runners.

Heatstroke occurred in four apparently normal but inexperienced runners who were involved in road races of 10, 16, 32, and 42 km. Each of the runners attempted to increase his running pace by approximately 1 min/km during the last 5 km of the race. Symptoms of heatstroke occurred within five to ten minutes of the onset of increased effort. In three cases, environmental conditions (temperatures, 24 to 26 degrees C) were contributory. Specific guidelines and instructions are needed for inexperienced runners who enter distance road races.

Locus of control and behavior in treatment groups.

Studied the Rotter Locus of Control scale for effective prediction of behavior in small groups. Subjects were 205 male VA Hospital patients participating in self-directed groups who completed the AGCT, Psychological and Somatic Symptom Scales, and Rotter's I-E measure of locus of control. Group behavior was measured through sociometry and a Group Member Evaluation form. Three hypotheses were not supported: (a) Persons scoring high in the direction of internal control (internals) will be more likely to act to influence their social environment; (b) internals will be more active than externals in gathering and processing information in group discussions, and (c) internals will be more self-directed and less susceptible to being influenced by others. Two hypotheses were supported: (a) externals will express more somatic and psychological complaints than internals, and (b) externals will be perceived as behaving more defensively than internals. In contrast, intelligence was correlated with a large number of group process measures. Locus of control and intelligence measures predict different kinds of behavior in groups.