Jeffrey A. Gliner

Air Pollution, Exercise, and Heat Stress

Twenty young men, smokers and non- smokers, were tested for maximal aerobic power in a 35 C environment under four ambient air conditions: (1) filtered air (FA), (2) 50 ppm carbon monoxide (CO), (3) 0.27 ppm peroxyacetyl nitrate (PAN), and (4) CO plus PAN. Carbon monoxide was effective in reducing the work time of the nonsmokers and in eliciting changes In the respiratory patterns of both smokers and nonsmokers. No significant physiological effects were noted during the PAN exposure. Maximal aerobic power was not affected by any pollutant condition. Since the concentrations of CO represented a first-stage alert level for the Los Angeles area, it appears that the air pollution standard for this pollutant is set at a realistic level for healthy young men doing strenuous work for a relatively short period of time.

Perception of effort and respiratory sensitivity during exposure to ozone

The purpose of this study was to examine the effects of exposure to the air pollutant ozone during exercise on perception of effort and to evaluate perceptual sensitivity to respiratory responses during this exposure. Fourteen male subjects were exposed to ozone concentrations of 000,030, and 0 50 p.p.m. during both resting and bicycle ergometer exercise treatments. Ratings of perceived exertion were obtained periodically during the 40min exercise period. Perceptual exponents were determined from magnitude estimation and production of lung volumes obtained before, at the approximate midpoint, and at the end of the 2 hour exposure period. Significant (p<0 01) decrements in FVC, FEV1, and MEF25-75 resulting from ozone exposure were greater immediately following an exercise bout. Perception of effort based on sensory input from above the waist (central) increased significantly (p<0 05) with increasing ozone concentrations. The increase in central perceived exertion appeared sooner in the exercise period and ...

Preferred Tempo, Work Intensity, and Mechanical Efficiency

Two experiments were carried out to determine the relationship between preferred tempo, work intensity, and mechanical efficiency. During Exp. 1, five inexperienced subjects worked at 0 Newtons 10 min. each day for seven days. Results demonstrated that (1) preferred tempo remained very consistent from Minute 1 to Minute 10, (2) this tempo was statistically reliable from day to day, and (3) variability of preferred tempo decreased from the first day to the seventh day in four out of five subjects. During Exp. 2, four subjects from Exp. 1 cycled at workloads of 0.0, 4.9, 14.7, and 24.5 Newtons for 10 min. each on three different occasions. Oxygen uptake, heart rate, ventilation, and respiratory frequency all increased as a function of increased workload and as a function of time within, workload for 14.7 and 24.5 Newtons. 2 of the 4 subjects maintained a constant tempo within any workload but decreased their over-all rates as a function of increased resistance. There was no direct relationship between preferred tempo and mechanical efficiency. It was concluded that timing characteristics of the task may be changed to fit an increase in workload. However, once initiated, the tempo does not change even when metabolic demands are altered.

Accuracy and precision of matching inspired lung volume.

Institute of Environmental Stress, University of California, Santa Barbara, California 93106 Three questions were asked: How accurately can lung volumes be reproduced? Do the underlying sensory continua of inspired lung volume subscribe to Weber’s law? Are planned inspirations more accurately reproduced than constrained inspirations? The ability to match inspired lung volume was investigated utilizing the psychophysical method of average error. Fourteen subjects participated in two different conditions in order to answer these questions. The results indicated that inspired lung volumes were reproduced much more accurately than had been previously reported. The sensitivity of change for planned inspirations was identical to that of constrained inspirations (k = 018). However, the absolute threshold was significantly greater for the constrained group. The underlying sensory continua subscribed to a generalized version of Weber’s law. These results are discussed within the context of our present knowledge of receptor information of movement.

Spectral analysis of electroencephalogram during perceptual-motor learning

Spectral analysis of the electroencephalogram was utilized to determine attention demands during learning of a perceptual motor task. Fifteen subjects participated in the task which consisted of 15 trials of the mirror star learning task. EEG was monitored bilaterally from the occipital and parietal lobes during each trial and analyzed for intensity and mean frequency components within five different bandwidths. All subjects rapidly improved performance in terms of both time and error reduction although the former measure appeared to be a better fit of the supradiagonal form of matrix typically found for this type of learning. Mean alpha frequency increased slightly during the task while delta frequency decreased.

Carbon monoxide exposure and information processing during perceptual-motor performance

SummaryThis study examined the influence of exposure to ambient carbon monoxide resulting in final carboxyhemoglobin (COHb) levels of approximately 5.0% on the ability to process information during motor performance. Subjects (n=16) performed a primary reciprocal tapping task and a secondary digit manipulation task singly and/or concurrently during 2.5 h exposure to room air (0 ppm CO) or 100 ppm CO. Five levels of tapping difficulty and two levels of digit manipulation were employed. Tapping performance was unaffected when COHb levels were as high as 5%. However, at this level of COHb it was noted that CO exposure interacted with task difficulty of both tasks to influence reaction time on the digit manipulation task. It was concluded that motor performance was not influenced by exposure to CO leading to COHb concentrations of 5%. Task difficulty was a significant factor mediating behavioral effects of CO exposure.

Dynamic lung function changes following long-term work in polluted environments

Ten young males (mean age 23.1 years) and nine middle-aged males (mean age 47.8 years) forming two groups (smokers and nonsmokers) performed a simple spirometric evaluation test prior to and following 4 hours exposure to four ambient conditions at two temperatures: 25°C dry bulb (DB), 30% rh and 35°C DB, 30% rh). The ambient conditions were filtered air, 50 ppm carbon monoxide in filtered air, 0.24 ppm peroxyacetylnitrate (PAN) in filtered air, and a combination of all three above conditions. During the 4-hour exposure, the subjects performed 3.5 hours of submaximal work (35% VO2max) resulting in a ventilation of 20–30 liters/min BTPS. The FVC of the younger subjects was reduced (4–7%) following exposure to conditions containing peroxyacetylnitrate (P < 0.05). The older subjects had no significant change in pulmonary function due to pollutants, suggesting an age-related susceptibility to the oxidant pollutants, such as PAN. Thermal stress reduced the FVC of younger subjects 5.5% (P < 0.01). There were no interactions between pollutants, temperature, or smoking habits. Exercise alone was effective in changing FEV1.0FVC, % of all subjects of both age groups. It was suggested that oxidant-type pollutants act on the dependent regions of the lung, while exercise appeared to stimulate the lung during forceful expiration.

Wandering Atrial Pacemaker Associated with Repetitive Respiratory Strain

Electrocardiographic responses of body-builders and control subjects obtained during the performance of static and dynamic Valsalva maneuvers were studied to determine the causative stimulus for wandering pacemaker activity. The incidence of shifting or wandering pacemaker was nearly double in body-builders, suggesting that this is an occupational or activity-related arrhythmia. The causative mechanism is briefly discussed.

Circulatory changes to alcohol, anxiety and their interactions.

Summary The effects of alcohol (0.16 g %), anxiety, and their interaction on circulatory parameters were examined. Electric shocks to the tails of the rats preceded by a 10-sec auditory signal were utilized to induce the anxiety condition. A significant increase in heart rate was found as a function of anxiety, regardless of alcohol. On the other hand, a significant decrease in both systolic and diastolic blood pressure was observed under alcohol, irrespective of anxiety. Increases in blood flow to the viscera, heart, and lungs were found after alcohol ingestion. An increase in blood flow to selected skeletal muscle was observed during the anxiety condition suggesting a defensive reaction. The few significant interactions observed when comparing the combination of alcohol and anxiety as opposed to alcohol or anxiety separately suggested that there were no circulatory interactions between these two conditions.

Perceptual cues used in reproduction of inspired volume

Man is capable of reproducing an inspired lung volume (IV) with relative precision (±3 %–8 %). To investigate the importance of cues which may be used to determine IV, we performed two experiments. In each, the subject inspired a “standard” breath (from resting end~xpired lung volume) corresponding to 25%, 50%, or 75% of inspiratory capacity (IC) and then expired nearly completely. From this expired volume, the subject either tried to reproduce the tidal volume (i.e., volume of air inspired) of the first breath (volume reproduction) or to reproduce the previous end-inspired lung volume (position reproduction). The constant error indicated that subjects overestimated tidal volume by about 200 ml. Despite this overestimation, the variability of reproduction was less for volume reproduction than for position reproduction when IV was small. The JND for volume reproduction increased linearly with increasing IV, whereas the JND for position reproduction was similar at all IVs so that the Weber ratio decreased. These observations suggest that, in the perception of inspired volume, the sensation of end-inspired position is important when the inspired volume is large, but that subjects apparently rely on some other cue to reproduce small lung volumes accurately.