Christian W. Zauner

Effect of aerobic exercise training on patients with systemic arterial hypertension

One hundred five patients with established diastolic hypertension were enrolled in an exercise program to examine the effect of aerobic conditioning on blood pressure. In four patients, the decrease in mean blood pressure was less than 5 mm Hg; in all others, there was a significant decline in arterial blood pressure. In 58 patients who were not taking drug medication in the pre-exercise period, mean blood pressure decreased by 15 mm Hg. Of 47 patients receiving drug therapy during the pre-exercise period, 24 were able to discontinue all medication. Mean blood pressure in this group fell from 116.9 +/- 6.5 mm Hg to 97.2 +/- 9.2 mm Hg as a result of exercise. In patients still taking antihypertensive drugs, mean pressure decreased from 120.9 +/- 28.8 mm Hg to 104.4 +/- 17.9 mm Hg after three months of exercise. It is concluded that in patients physically and emotionally able to exercise, a significant decline in blood pressure can be achieved.

Effects of phosphate loading on 2,3-diphosphoglycerate and maximal oxygen uptake.

Increased concentration of red blood cell 2,3-diphosphoglycerate (RBC 2,3-DPG) shifts the hemoglobin-oxygen dissociation curve to the right, thus theoretically allowing better oxygenation of tissues. To determine whether such a shift is physiologically significant, we investigated the effects of oral phosphate loading on several parameters including plasma phosphate concentration, RBC 2,3-DPG, hematocrit and hemoglobin concentration, maximal oxygen uptake (VO2max), and degree of lactic acidemia in 10 well-trained distance runners. After control determinations were made, either a phosphate load or a placebo was given for 3 d before the athlete was restudied. A placebo and two phosphate-loading studies were performed at weekly intervals, followed by 2 wk of rest and another post-intervention control study. Blood samples for control values were drawn before and after a standard warm-up period, after treadmill exercise at a 10% grade, and at the completion of the VO2 determination. After oral phosphate loading there was a significant increase in serum phosphate and RBC 2,3-DPG. Maximal oxygen uptake was significantly increased and correlated with the rise in RBC 2,3-DPG (r = 0.81). The increase in blood lactate after exercise on the 10% grade was attenuated during sessions which followed phosphate loading.

Marathon running: physiological and chemical changes accompanying late-race functional deterioration

SummaryTwenty-one experienced runners were studied before, during and immediately after a marathon race to ascertain whether either depletion of energy substrate or rise in body temperature, or both, contribute to laterace slowing of running pace. Seven runners drank a glucose/electrolyte (GE) solution ad libitum (Na− 21 mmol 1−1, K+ 2.5 mmol l−1, Cl− 17 mmol l − l, PO42− 6 mmol 1−1, glucose 28 mmol 1−1) throughout the race; 6 drank water and 8 drank the GE solution diluted 1:1 with water. Although average running speeds for the three groups were not significantly different during the first two-thirds (29 km) of the race, rectal temperature was significantly higher (P < 0.05) and reduction of plasma volume was greater (P <0.05) in runners who replaced sweat losses with water. During the last one-third of the race, the average running pace of the water-replacement group slowed by 37.2%; the pace slowed by 27.9% in the 8 runners who replaced their sweat loss with GE diluted 1:1 with water (1/2 GE) and 18.2% in runners who replaced fluid loss with full-strength solution (GE). Eleven runners (5 in the water group, 4 in the 1/2 GE group and 2 in the GE group) lapsed into a walk/run/walk pace during the last 6 miles of the race. Ten of these had a rectal temperature of 39° C or greater after 29 km of running, and plasma volume in these runners was reduced by more than 10%. Only 1 runner among those who ran steadily throughout the race had such an elevation of temperature and reduction of plasma volume. A significant reduction in plasma glucose concentration (less than 3.3 mmol 1−1) was present in 5 of the 11 walk/run/walk subjects and in none of those who ran steadily. The results are consistent with the suggestion that assumption of the walk/run/walk pace resulted from high body temperature associated with either diminished plasma volume or low blood sugar.

Pulmonary Diffusing Capacity and Physical Working Capacity in Swimmers and Non-Swimmers during Growth

We measured physical working capacity at a heart rate of 170 bpm (PWC170) and diffusing capacity for carbon monoxide (DLCO) in two groups of children ranging in age from 9 to 17 years. One group was formed of highly trained competitive swimmers and the other of age, sex and size matched untrained counterparts. Bicycle ergometry was used to establish PWC170. The DLCO was measured at rest (DLCO rest) and while pedalling at 170 bpm (DLCO ex). The PWC 170, DLCO rest and DLCO ex were significantly higher in swimmers than in non-swimmers. Repeated measurements in the same subjects show that individual increases in DLCO rest and DLCO ex were result of both growth and training.

The Relative Effect of Hypoxia and Gravity on Pulmonary Blood Flow

The influence on the partition ofpulmonary blood flow and ventilation and on arterial blood gas tensions by inhalation of different oxygen concentrations with the superior and inferior lung in the rig

Regional lung function and central haemodynamics in the right lateral body position during hypoxia and hyperoxia.

In 13 healthy males pulmonary blood.flow distribution (PBFD), pulmonary artery pressure (PAP), and cardiac output (Q) were measured in the right lateral body position during 10 and 100% O2

Cardiorespiratory efficiency at submaximal work in young and middle-aged women.

Seventeen middle-aged women and 26 younger women were studied while walking at 3 mph and a 5% grade on a motorized treadmill. This was submaximal work for all subjects and is equivalent to the intensity of everyday activity. The middle-aged women had a significantly greater oxygen uptake, ventilatory equivalent, and heart rate, suggesting a relative cardiorespiratory inefficiency at this submaximal work intensity. This phenomenon is most likely a function of body size, however, since dividing the submaximal oxygen uptake by body weight rendered the mean difference between the two groups statistically insignificant. The age-associated reduction in cardiorespiratory efficiency at submaximal exercise is thus due primarily to weight gain rather than to actual systems degeneration. Maximal oxygen uptake, that associated with maximal physical effort, was significantly reduced in the older subjects, and this is probably due to a combination of previous life-style habits and aging.

Arterial-Venous Differences Across the Lungs in Plasma Triglyceride Concentration

Arterial-venous differences in plasma triglyceride across the lungs were determined in healthy human subjects before, during and following infusion of a soybean oil emulsion into the superior vena cava. Samples were acquired from the pulmonary and brachial arteries. A significantly greater mean concentration of triglyceride in venous as opposed to arterial blood was evident following 12 min of infusion (pless than 0.001), with a tendency for the retained lipid to be released during the postinfusion period. It could be calculated that during infusion the lungs retained about 20% of the available triglyceride, or 3 mmol/min.

Pulmonary arterial-venous differences in lipids and lipid metabolites.

This study was designed to reevaluate the effectiveness of the lungs in taking up lipids from the blood, and to establish whether or not the blood triglycerides so extracted are metabolized. 8 normal human males were studied. With the subject fasting and supine, a percutaneous catheter was placed in the pulmonary artery, another in the superior vena cava, and a third in the brachial artery. Samples of mixed venous and arterial blood were drawn by syringe from the pulmonary and brachial arteries, respectively. Infusion of a triglyceride emulsion (20% Intralipid) into the superior vena cava was begun at 4.7 ml/min. After 12 min of infusion, mixed venous and arterial samples were taken and infusion was discontinued. 15 min following termination of infusion, blood samples were again drawn. Analysis showed the lungs to be retaining about 25% of available triglyceride. Cholesterol concentration was unaffected. Arterial-venous differences in glycerol and free fatty acid were insignificant, suggesting no metabolism of triglyceride by lungs. The lungs apparently serve as a mechanical screen to triglyceride.

RESULTS OF STUDIES OF POTENTIAL LIGHT SPECTRUM EFFECTS ON HUMAN PERFORMANCE

Recent findings suggest that the spectrum of light from fluorescent lamps may influence human behavior and physiology. To evaluate possible light effects on exercising humans, physical performance was measured under two widely different light spectra: the spectrum from one bulb‐type (General Electric Croma‐50) approximated that of sunlight, while the other (General Electric Delux Warm White) was heavy in the red end of the spectrum. Twenty eight moderately active subjects (14 males:14 females; ages 20–32 yrs) were acclimated to light conditions for 30 min before being tested to maximal effort with a modified Balke treadmill protocol (Balke et al., 1954). The interval between tests under each light condition averaged 6.9 days. Heart rate and respiratory parameters were measured at rest, submaximum exercise (5% treadmill grade), maximum, and 3 min after test termination. Data analysis (2‐way ANOVA) indicated expected differences between genders only, with no effects attributable to light spectrum. The mean V02 max was 44.8 ml/kg min for males vs 38.6 ml/kg min for females. Mean maximum heart rate was 197 bpm for males and 194 bpm for females. Mean maximum treadmill grade averaged 24.3% for men and 22.0% for women. A significant difference in submaximum heart rate was found to be due to presentation order. These results fail to indicate that fluorescent light type influences physical performance.