Psychophysiological effects of confinement and reduced physical activity



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The present study was concerned with investigating the effects of confinement and restricted activity on perceptual-motor coordination and intellectual functioning as defined by five performance tests. The study was also designed to examine relationships between these performance measures and cardiovascular responses to the experimental condition. The performance variables included simple reaction time, and psychometric measures of visual tracking ability, visual-motor coordination, discrimination and perception, and ability to solve simple addition problems. Cardiovascular variables were selected on the basis of heart rate and blood pressure responses to a provocative stimulus, passive body tilt, which was administered before and after each experimental period to determine the effects of recumbency on the cardiovascular system. The independent variable consisted of a 10-day recumbency period during which subjects were required to remain in bed at all times. The subjects underwent three recumbency periods separated by a 23-day recovery period. Observations for the present study were obtained during the second and third recumbency periods, which minimized the effects due to novel experimental conditions. The battery of performance tests was administered immediately before and after passive body tilt to determine the effects of the cardiovascular stressor on performance independent of recumbency, the effects of the intervening recumbency period on these performance measures, and the association between overt performance measures and cardiovascular responses. It was assumed that alterations in performance and cardiovascular reactions would be observed following the period of confinement and reduced physical activity. A decrement in reaction time was expected to occur following recumbency which would be associated with those cardiovascular reactions suggesting impaired circulatory functioning. Speed of performance, as measured by number attempted on the psychometric measures, was expected to decline, while accuracy of performance would not be significantly altered. Speed and accuracy on the psychometric measures tended to increase after tilt as compared with pre-tilt measures, both before and after bed recumbency. Thus, the predicted decrease in speed was not confirmed. These results indicate that performance on simple cognitive tasks tends to remain the same or even improve. Post-tilt reaction time was consistently longer than pre-tilt responses. The decrement in reaction time change, as reflected by the difference between pre- and post-tilt measures, was significantly greater after the second recumbency period than the decrement observed before recumbency. These results were not consistent for the third recumbency period. Change in performance before the third recumbency period showed a significant decrement, whereas the change observed after recumbency was not significantly decreased. However, the difference between before-after change scores reached significance for the second recumbency period, but not for measures based on the third recumbency. The post-tilt decrement in reaction time after the third recumbency was similar to that observed before the second recumbency, suggesting adaptation to the necessity for performing under the non-optimal conditions presented by the tilt stimulus, or habituation of the response to reaction time tests. Time to minimum pulse pressure from start of tilt was the only consistent cardiovascular variable to contribute to the variance in reaction time. The results indicated that a longer interval to reach minimum pulse pressure from start of tilt was associated with maintaining stable reaction time, as measured by the difference between pre- and post-tilt responses. This relationship was more pronounced on the measures obtained after recumbency. One of the symptoms of intolerance to tilt is a narrowing of pulse pressure. A longer interval before reaching minimum pulse pressure during a provocative stress test is associated with less cardiac impairment. This index of the ability to tolerate cardiovascular stress was associated with the ability to maintain stable reaction time.



Sensory deprivation, Physical activity