Key result
During +2Gz centrifugation, mean arterial pressure increased similarly in both tall (23 ± 2 mmHg) and short (22 ± 2 mmHg) males, with no significant difference between the groups.
Why the study?
Does +2G centrifugation increase mean arterial pressure more in tall than in short males in the seated position?
Does +2G centrifugation increase mean arterial pressure more in tall than in short males in the seated position?
Absolute Event Rate: 23% vs 22%
Gravito-inertial stress increases mean arterial pressure similarly in short and tall males, but induces a greater heart rate increase and stroke volume decrease in tall males, likely due to a larger hydrostatic pressure gradient.
Similar MAP rise during +2Gz irrespective of height; leaves open height effects on other hemodynamics in gravito-inertial stress.
It is known that arterial pressure correlates positively with body height in males, and it has been suggested that this is due to the increasing vertical hydrostatic gradient from the heart to the carotid baroreceptors. Therefore, we tested the hypothesis that a higher gravito-inertial stress induced by the use of a human centrifuge would increase mean arterial pressure (MAP) more in tall than in short males in the seated position. In short (162-171 cm; n = 8) and tall (194-203 cm; n = 10) healthy males (18-41 yr), brachial arterial pressure, heart rate (HR), and cardiac output were measured during +2G centrifugation, while they were seated upright with the legs kept horizontal (+2Gz). In a separate experiment, the same measurements were done with the subjects supine (+2Gx). During +2Gz MAP increased in the short (22 ± 2 mmHg, P < 0.0001) and tall (23 ± 2 mmHg, P < 0.0001) males, with no significant difference between the groups. HR increased more (P < 0.05) in the tall than in the short group (14 ± 2 vs. 7 ± 2 bpm). Stroke volume (SV) decreased in the short group (26 ± 4 ml, P = 0.001) and more so in the tall group (39 ± 5 ml, P < 0.0001; short vs. tall, P = 0.047). During +2Gx, systolic arterial pressure increased (P < 0.001) and SV (P = 0.012) decreased in the tall group only. In conclusion, during +2Gz, MAP increased in both short and tall males, with no difference between the groups. However, in the tall group, HR increased more during +2Gz, which could be caused by a larger hydrostatic pressure gradient from heart to head, leading to greater inhibition of the carotid baroreceptors.
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Arvedsen et al. (2015) studied Healthy (n=18). Tall body height during +2G centrifugation vs. Short body height was evaluated on Increase in mean arterial pressure (MAP) during +2Gz. During +2Gz centrifugation, mean arterial pressure increased similarly in both tall (23 ± 2 mmHg) and short (22 ± 2 mmHg) males, with no significant difference between the groups.
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