62 research outputs found
SPACE FEVER : CORE BODY TEMPERATURES IN ASTRONAUTS UNDER REST AND EXERCISE ON THE INTERNATIONAL SPACE STATION (ISS)
Introduction
In Space, thermoregulation in humans should be altered due to i) changes in convective heat loss, ii) body
composition, and iii) a diminished production and/or decreased efficiency of evaporation, especially during
physical excercise. We hypothesized that in astronauts for a given absolute level of work, body core temperatures
(CBT) should show a faster, higher, and longer lasting increase as compared to a similar exercise protocol on
Earth.
Material & Methods
11 astronauts (7 male, 4 females) were studied several times before, during, and after a physical exercise
protocol on ground and in space on ISS between 2010-2012. Out of these 11 astronauts we received complete
pre and post-flight anthropometric and body composition data from 10 astronauts, 6 males and 4 females with an
average age of 48.5 \ub1 3.9 years , height 1.76 m \ub1 0.07 [m], weight of 77.5 \ub1 16.2 [kg], body mass index of 24.7 \ub1
3.4 (kg/[m]2), a lean body mass preflight of 59.5 \ub1 11.9 [kg], and a fat mass of 18.0 \ub1 5.3 [kg].
Results
It was found that i) CBTs increased much faster in space as compared to baseline values at all time points
(p<0.05), ii) during exercise the absolute peakes of CBTs reached were significantly higher than preflight
(p<0.05), incidentally above 41.0 \ub0C, and iii) the post- excercise cooling periods were significantly prolonged
(p<0.05). However, most unexpected, we observed iv) that the resting CBTs were found to be elevated by 0.5-0.9
\ub0C inflight as compared to preflight (p<0.05), and returned only gradually to control level 30 days after postflight.
Discussion & Conclusions
We conclude that i) in space already during a short-term physical exercise high CBTs >40.0 \ub0C can be reached in
astronauts, ii) post-exercise 'cool-down' periods inflight are prolonged, and iii) most remarkable in space the setpoint
of CBT is shifted to a higher level up to 0.9 \ub0C as compared to pre- and post baseline values. The latter shift
of core temperature to a higher set- point is presumably induced by immunolological processes and might
contribute to our understanding of fore-most isolated observed adaptive changes in humans during long-term
space flight such as negative energy balance and peripheral vasoconstriction
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