The Effects of Roll vs. Pitch Rotation in Humans Under Orthostatic Stress

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Authors
  1. Cheung, B.
  2. Goodman, L.
  3. Hofer, K.
Corporate Authors
Defence and Civil Inst of Environmental Medicine, Downsview ONT (CAN)
Abstract
It has been known since 1953 that pre-exposure to less than +1 Gz will reduce subsequent +Gz-tolerance. With few exceptions, during operational flying, the transition from hypogravity to hypergravity involves roll as well as pitch rotation. We examined the effect of roll vs. pitch rotation while undergoing transition from hypogravity to +1 Gz on a tilt table. Twelve subjects (28-47 yr old) were rotated at 45 degrees-s1(-) from head-up (HU) at 15 degrees relative to gravitational vertical to 135 degrees head-down (HD) and back to the HU position after different HD dwell times. HD dwell times were set at 7, 15, and 30 s. The subject was rotated about the interaural axis (pitch) and about the naso-occipital axis (roll). Both the HD dwell times and axes of rotation were randomized within and across subjects. BP and heart rate were recorded during the HU-HD-HU maneuver. Analysis of variance, repeated measure design revealed that the rate and magnitude of BP decrease induced by the HD to HU maneuver is significantly higher (p<0,01) in roll than in pitch during all HD dwell times. The decrease of BP at 7s is significantly (p<0.01) higher than at 15s and 30s. Heart rate increases significantly higher (p<0.01) in pitch than in roll at 7s-dwell time. Our results suggest that the compensatory mechanism to orthostatic stress is more efficient in response to pitch than roll rotation.
Keywords
Sensory physiology;Spatial disorientation;Orthostatic hypotension;G-tolerance
Report Number
DCIEM-98-P-42 — Reprint
Date of publication
07 Jul 1998
Number of Pages
11
Reprinted from
Aviation, Space, and Environmental Medicine, vol 70, no 10, 1999, p 966-974
DSTKIM No
99-01789
CANDIS No
511956
Format(s):
Hardcopy;Document Image stored on Optical Disk

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