Lyle H. Hamilton

Alterations in pulmonary function consequent to competitive marathon running.

This study was designed to investigate the mechanisms underlying the significant reductions in vital capacity after marathon racing originally reported over 50 years ago. Spirometric, maximum expiratory flow-volume (MEFV), DLCO and residual volume (RV) measurements were made on 13 runners (11 males and 2 females) 1--2 weeks prior to the marathon, immediately after finishing the race, and again the next day. An average 0.48 L (8.6%) reduction in post-race forced vital capacity (FVC) was accompanied by an equivalent increase in RV. Thus, total lung capacity did not change, and the reduction in FVC was a result of an expiratory rather than an inspiratory limitation. Post-race FEV1 and FEF200-1200 remained unchanged while FEV1-2, FEF1 and FEF2 were reduced 19.7, 26.7 and 23.3%, respectively. Mean DLCO was unchanged. Pulmonary function on the following day was similar to that observed on the control day. These data indicated that after the race, expiratory flow was unaffected at high lung volumes, but was decreased at low lung volumes (within the effort-independent portion of the MEFV curve). The results are compatible with small airway closure occurring at an increased lung volume, which would result in a decreased FVC and an increased RV.

Metabolic changes in exercise-induced asthma

Five patients with a history of post‐exercise bronchoconstriction and eleven control subjects were exposed to gradually increasing work loads on a bicyle ergometer. The asthmatic patients showed higher blood lactic acid levels at all work loads than the control subjects. In contrast to findings in the controls, the plasma free fatty acid in the asthmatics failed to ‘rebound’ following the cessation of exercise; and in two out of three patients plasma FFA did not rise after epinephrine injection. In addition, the asthmatic patients consumed less oxygen during the exercise than the controls.

GAS CHROMATOGRAPHY FOR RESPIRATORY AND BLOOD GAS ANALYSIS

Gas chromatography is a relatively new technique that can be used for the analysis of a wide variety of materials. Sufficient progress has been made in chromatographic techniques within the last few years so that the method can provide the sensitivity and accuracy required for analysis of gas mixtures important in medicine and physiology. This report is concerned primarily with the technique for measuring oxygen and carbon dioxide in respiratory gas and blood samples, but the technique has been applied to other gases equally important in clinical and research f ie ld~. l -~

Time course of lung volume changes during prolonged treadmill exercise

It has been known since the 1920s that runners completing marathon races have reduced forced vital capacity (FVC) values. To investigate the time course of these lung volume alterations, we measured FVC and residual volume (RV) in 11 runners before, after, and at 30-min intervals during a 2.5-h treadmill run at just under their marathon pace (70% VO2max). Mean distance run was 21.5 +/- 1.5 (SD) miles in the 2.5-h period. During the first 60 min, both RV and total lung capacity (TLC) decreased by 110 ml, however, this change was not significant (P greater than 0.05). A high correlation (r = 0.93) was observed between delta RV and delta TLC during the first 5 min, while FVC remained unchanged. From 60-90 min, all lung volumes remained constant. From 90-150 min, lung volumes changed in a direction similar to that observed after a marathon, i.e., FVC decreased significantly (5.51 to 5.37 liter between 90 and 150 min, P less than 0.05), TLC remained unchanged (7.41 vs 7.42 liter, P greater than 0.05), and RV showed a nonsignificant increase from 1.90 to 2.05 liter (P greater than 0.05). The data are consistent with multiple mechanisms playing a role in pulmonary function changes during prolonged exercise. The smaller mean decrease in FVC observed in this study, as compared to that found during a marathon, suggested that the marathon imposes a greater demand on the lungs than did treadmill exercise of the duration and relative intensity used in this study.

Metabolic changes in exercise-induced and methacholine-induced bronchoconstriction

Metabolic and physiological responses to graded exercise and methacholine challenge were investigated in asthmatics with or without exercise-induced bronchoconstriction. The results showed that after methacholine challenge, free fatty acid levels increased only in patients with exercise-induced asthma, while they increased in both groups of asthmatics after treadmill exercise. No significant changes were noted in plasma lactic acid levels, ventilation, or oxygen consumption among the groups studied. These data suggest that asthmatics with exercise-induced bronchoconstriction may differ from other asthmatics in some of their metabolic responses.

Oxygen uptake, ventilation, and heart rate. Study in Negro children during strenuous exercise.

Various physiological responses to strenuous exercise were measured in a group of 100 clinically healthy Negro children from the “inner core” area of Milwaukee. The subjects included 47 boys and 53 girls with an age range of 9 to 11 years. The height, weight, and body surface area of the subjects in this study were consistently lower than data reported in the literature for similar age groups. The work capacity, employing the criteria of “maximal” oxygen uptake, was also lower than most data reported on similar age groups. The data suggest that the physical work capacity of “disadvantaged” children is reduced, perhaps reflecting a poor nutritional status.

The Effect of Heparin Pretreatment on Development and Clearing of Alimentary Lipemia

V ARIOUS abnormalities of lipid metabolism have been reported in patients with atherosclerotic heart disease, among them elevation of plasma triglyceride levels” and reduced clearing of alimentary lipemia.”4 Since it has been observed that heparin accelerates the removal of triglycerides from the blood stream�’6 and promotes the clearing of lipemia,7’8 some investigators have advocated its use in the treatment of atherosclerosis.9”0 Although there is no question about the effectiveness of heparin in clearing a previously developed lipemia, relatively little is known as to whether heparin can be used to prevent or modify the postprandial rise in blood lipid levels by appropriate timing of its administration in relation to the mealtime. The present study describes an investigation of the lipemia-clearing effects of heparin injected shortly before and 3 hours after inges