Commercial spaceflight participant G-force tolerance during centrifuge-simulated suborbital flight.
BACKGROUND
Medical knowledge of the human body in microgravity and hypergravity is based upon studies of healthy individuals well-conditioned for such environments. Little data exist regarding the effects of spaceflight on untrained commercial passengers. We examined the responses of potential spaceflight participants (SFP) to centrifuge G-force exposure.


METHODS
There were 77 individuals (65 men, 12 women), 22-88 yr old, who underwent 6 centrifuge runs over 48 h. Day 1 consisted of two +Gz runs (peak = 3.5+Gz, run 2) and two +Gx runs (peak = 6.0+Gx, run 4). Day 2 consisted of two runs approximating a suborbital spaceflight profile. Data included blood pressure, electrocardiogram, and postrun questionnaires regarding motion sickness, disorientation, greyout, and other symptoms.


RESULTS
Of the 77 participants, average age was 50.4 +/- 12.7 yr. Average heart rate (HR) varied by sex and direction of G-exposure (+Gz: F 150 +/- 19, M 123 +/- 27; +Gx: F 135 +/- 30, M 110 +/- 27). Age and peak HR were inversely related (HR < 120 bpm: 60.2 +/- 12.2 yr, HR > 120: 47.1 +/- 10.9 yr). HR during peak G-exposure for the final run was associated with post-run imbalance (no imbalance: HR 126 +/- 26, imbalance: HR 145 +/- 21); no other significant hemodynamic change, sex, or age variation was associated with imbalance. Age and greyout were inversely associated; there was no association between greyout and vital sign change, sex, or G-force magnitude. Baseline/pretrial mean arterial pressure (MAP) was not associated with any symptoms.


CONCLUSIONS
The results suggest that most individuals with well-controlled medical conditions can withstand acceleration forces involved in launch/landing profiles of commercial spaceflight vehicles. Further investigation will help refine which conditions present significant risk during suborbital flight and beyond.
University of Texas Medical Branch, Department of Preventive Medicine and Community Health, 301 University Blvd, Galveston, TX 77555-1110, USA. rsblue@utmb.edu
Rebecca S
RS
Blue
Jon M
JM
Riccitello
Julia
J
Tizard
Richard J
RJ
Hamilton
James M
JM
Vanderploeg
D000054:Acceleration / Q000009:adverse effects*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001794:Blood Pressure; D003221:Confusion / Q000209:etiology; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate; D006801:Humans; D018471:Hypergravity / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D009041:Motion Sickness / Q000209:etiology; D004856:Postural Balance; D013026:Space Flight; D011795:Surveys and Questionnaires; D013575:Syncope / Q000209:etiology; D014195:Travel; D055815:Young Adult