THERMOREGULATION IN HUMANS DURING LONG-TERM SPACEFLIGHT (THERMOLAB)
Research Area: Cardiovascular and Respiratory Systems
Expedition(s): 21-ongoing
Principal Investigator(s): ● Hanns C. Gunga, Charité Universitätsmedizin, Berlin, Germany
RESEARCH OBJECTIVES
Thermoregulation in Humans During Long-term Spaceflight (Thermolab) investigates core
temperature and heart rate during rest and exercise to determine the physiological strain index
(PSI) in the course of a long-term microgravity exposure (International Space Station [ISS]
mission). A newly developed thermosensor for core temperature is applied, which enables non-
invasive study and is very convenient for core temperature measurement during rest and
exercise in weightlessness.
SPACE APPLICATION
The information obtained by this study leads to a better basic understanding of heat transfer
and the thermal regulation in humans under weightless conditions. Such data helps with
monitoring and maintenance of astronaut health and well-being in orbit.
EARTH APPLICATION
By studying alterations in heat balance, thermoregulation and circadian temperature rhythms
in space, we also get a greater understanding behind the mechanisms by which these systems
work on Earth.
RESULTS
Core body temperature rises faster during exercise on the ISS than on Earth, probably caused by
fluid shifts and modified heat flow away from the body. Data indicated that adaptation can be
seen in the first 6 weeks on the ISS with an increase in core body temperature by around 1-1.5°C
though this settles down to an increase of around 0.5 - 1°C above preflight core body temperature
as the mission extends. With the core temperature rising faster on the ISS, it was also noticeable
that the body temperature took longer to cool back down to core temperature after exercise.
The measurement of the core body temperature together with cardiovascular measurements
during the NASA VO2Max protocol can be used to evaluate the subject's state of fatigue, which
is very important for optimizing mission success. The non-invasive double sensor could be a very
useful diagnostic tool for recognizing early warning signs of fatigue during, for example,
spacewalks in orbit. On Earth, firefighters (to recognize exhaustion/overheating) or jet pilots,
steel workers, miners, soldiers in combat, divers, etc, working in extreme conditions could all
benefit from this technology. It could also be used for monitoring during critical hospital
operations such as heart surgery or for monitoring babies in incubators.
This investigation is complete; however additional results are pending publication.