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Biomedical subjects

C Bard

Publications and source records attributed to C Bard.

60 records · Page 4Linked to original sources
PubMed1981

Influence of different types of physical fatigue on a visual detection task.

The present study was designed to investigate the effects of different types of physical fatigue-past demand for exertion-on the performance of a visual detection task performed with and without masking. 31 male subjects were first administered a VO2 max test and familiarized with the detection task. They were divided into two groups to control potential effects of masking. They were subjected to three experimental treatment involving the utilization of different sources of energy: (a) a short anaerobic alactic acid effort recruiting phosphocreatine, (b) a supramaximal effort (anaerobic lactic acid) recruiting glycogen without oxygen, and (c) a progressive (partially anaerobic) effort recruiting glycogen and oxygen. All three were performed on a treadmill. Blood samples were collected for the anaerobic lactacid and the partially anaerobic exercises. Once fatigued, all subjects undertook the detection task. A 2 X 3 X 2 X 8 analysis of variance, with repeated measures on the last three factors, was applied to the data (mask/no mask X type of exercise X pre-post performance measures X location of the letter to be detected). No significant difference was found for either the main effects or interactions, except for the location of the letter and the mask/no mask condition. It appears therefore that a physically fit population (mean VO2 max = 62.39 ml X kg(-1) X min(-1)) shows no detectable decrement in a perceptual task performed after fatiguing exercises recruiting various types of energy sources.

Adult↗
PubMed1981

The effects of physical or perceptual work loads on a coincidence/anticipation task.

This study was designed to analyze the effects of physical or perceptual work loads on a coincidence/anticipation task. Three experimental treatments were applied: (1) a physical work load, (2) a perceptual work load, and (3) a combination of the physical and the perceptual work loads. The dependent variable was performance on a coincidence/anticipation task, a throw at a moving target. Time errors and accuracy scores were recorded. The type of work load does not affect any of the dependent variables. However, all types of work load generated definite improvement pre- and posttest for the temporal constant error; better performance, as measured by constant error, was recorded for all subjects when the speed of the apparent movement being intercepted was 4.7 km/hr. Temporal variability was reduced in the subject performance at 8.1 km/hr.

Adult↗
PubMed1978

Influence of imposed metabolic fatigue on visual capacity components.

The present study was designed to investigate the effects of exercise to exhaustion on different components of visual capacity: visual field, and coincidence/anticipation capacity. 16 male subjects were first familiarized with the three visual tests, one day before being submitted to a prefatigue visual test. Metabolic fatigue was induced by working to exhaustion on a bicycle ergometer. Once fatigued, all subjects undertook the visual tests. Pre- and post-fatigue visual measurements were not significantly different. The results demonstrated the independence between metabolic fatigue and visual capacity.

Fatigue↗
PubMedDate not supplied

On the cognitive penetrability of posture control.

Postural sway increases with age. The decreased stability associated with postural sway often has been related to the reduced peripheral sensibility in the visual, vestibular, and proprioceptive systems. We examined whether the micropostural adjustments necessary for maintaining balance also require some cognitive processing. Young and older subjects were submitted to an auditory reaction time task while maintaining an upright posture on a force platform. The auditory stimuli were presented randomly when subjects were in a central or in an eccentric less stable postural position in four conditions of vision/surface. If the postural adjustments require some cognitive processing, a more eccentric position of the center of foot pressure (COP) would require more attention than a stable position of the COP because when an eccentric position is identified, a corrective response subsequently needs to be selected, programmed, and executed. The visual and surface conditions were altered to determine if additional attentional resources need to be allocated to the postural task when there is a reduction of the sensory information available. Results showed that as the sensory information decreased, the postural task became increasingly difficult for the elderly and required more of their attentional capacity (as indexed by increases in reaction time).

Acoustic Stimulation↗
PubMedDate not supplied

Upright standing and gait: are there changes in attentional requirements related to normal aging?

This study evaluates attentional requirements for maintaining an upright posture and for walking among young and elderly persons to determine if, with normal aging, there is a deficit and/or a modification in the allocation of the attentional resources necessary for balance control. Eight young adults and 8 elderly persons were asked to respond to an auditory reaction time (RT) task (secondary task) while in a seated position, while in a broad-support or narrow-support upright standing position, and while walking (primary tasks). Reducing the base of support yielded slower RTs for the elderly than for the young persons. When walking, the elderly persons adopted a slower speed than young persons. They also had a shorter stride length. These adaptations have been reported to produce a more secure gait. Even so, they responded to the probe RT task with greater delays than young adults. Together, the results suggest that normal aging requires that a greater proportion of attentional resources be allocated to the balance demands of postural tasks.

Adult↗