Maximal exercise testing safety.
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Data Collection↗
Biomedical subjects
R L Blessey
Publications and source records attributed to R L Blessey.
Health effects of ozone exposure in asthmatics.
To investigate whether ambient air quality standards for ozone adequately protect high-risk populations, we assessed pulmonary and biochemical responses of 22 asthmatic volunteers to 2-hour controlled exposures to ozone at concentrations approximating 0.2 ppm, with secondary stresses of heat and intermittent exercise. All subjects had physician-diagnosed asthma; clinically, they covered a range from minimal wheezing to persistent marked abnormality in forced expiratory performance. Control experiments included repeated sham exposures (to purified air with no ozone added) as well as brief exposures to the odor of ozone followed by purified air. No meaningful changes in forced expiratory measures, lung volumes, or single-breath N2 indices were found after ozone exposure relative to control. Symptoms, scored semiquantitatively, increased slightly but not significantly with exposure to ozone. Small but significant (P is less than 0.05) group mean blood biochemical changes occurred with exposure to ozone; these included increased glucose-6-phosphate dehydrogenase and lactate dehydrogenase activities, increased erythrocyte fragility, and decreased concentration of reduced glutathione. Hemoglobin concentration and acetylcholinesterase activity decreased with ozone and decreased to a lesser extent in control studies. Concentrations of ozone readily attainable in smog episodes thus appear to be capable of affecting blood biochemistry in at least some asthmatic persons, in the absence of obvious adverse pulmonary responses. Whether the biochemical effects represent harm to health or a normal response to stress remains to be determined.
Acetylcholinesterase↗
Metabolic energy cost of unrestrained walking.
Physiologic factors of metabolic energy cost as well as selected mechanical characteristics of gait are described in a group of 40 presumably normal men and women between the ages of 20 and 60 years. Special emphasis was placed on unrestrained (free cadence) walking to provide a reliable baseline for comparison to persons with physical gait impairments. Velocity of walking was the most important factor in determining oxygen uptake and was independent of age or sex. An empirical equation was established relating oxygen uptake to the speed of walking. The average velocity for men in unrestrained walking trials was 89 meters per minute; for women 74 meters per minute. These differences were related to the greater stride length in men. The average cadence selected by both sexes was 116 steps per minute. None of these factors was age dependent. Of the physiologic measures only systolic blood pressure was age dependent predictably rising with age. The mean heart rate was 103 beats per minute and did not vary significantly between men and women. The mean respiratory rate was 19 per minute; the mean respiratory quotient, 0.85, neither being age or sex dependent. Oxygen uptake values averaged 12.95 ml/kg-min for the population studied and again were neither age nor sex dependent.
Adult↗