Postural Status Research Articles

Role of postural status in the nocturnal hemodynamic patterns of nonhuman primates.

We compared the nocturnal hemodynamic patterns of seven tethered monkeys (Macaca mulatta) with those of seven chaired animals to determine whether the overnight changes are comparable in the two conditions. In both groups, we found a consistent hemodynamic pattern characterized by an overnight fall in cardiac output and central venous pressure and a rise in total peripheral resistance that maintained blood pressure homeostasis. The pattern of overnight change occurred despite major differences in response levels: cardiac output and central venous pressure were significantly elevated, and total peripheral resistance was significantly reduced at all times (from 1800 to 1200 h the following day) in the chaired animals relative to the tethered animals. This difference was probably due to an expanded plasma volume in the chaired animals, because stroke volume was also significantly elevated. Because the nocturnal hemodynamic pattern occurred under both conditions, it is likely that it is a stable biologic effect, which is probably related to an overnight loss in fluid volume that is not replaced in animals that sleep throughout the night.

Grip strength and exposure to hue differences in visual stimuli: Is postural status a factor?

In previous experiments investigating effects of color on muscle strength, subjects were seated during the test procedure, and although statistically significant, magnitude of color effect differences were very small. So as to explore the possible role of organismic state variables associated with body position, subjects in the present study were tested while standing. This time, no significant difference was found between hand dynamometer squeeze scores of 36 high school wrestlers as they stared at a pink, compared with a blue, stimulus card. Directions for future inquiry into muscle-specific loci of kinesiological color effects are considered. But the lack of unambiguously established experimental evidence as to the reliable effects of color on muscle strength is underscored.

Postural status as a factor in memory

The role of posture in nonsense-syllable learning was assessed by testing 32 Ss under contrasting conditions of congruent (i.e., learn erect-relearn erect; learn supine-relearn supine) and incongruent (i.e., learn erect-relearn supine; learn supine-relearn erect) body orientations in learning and relearning. Under congruent postures there is significantly greater saving in relearning; this effect holds only in the early stages of the process of recall (i.e., with a weak criterion).