CREWS HEALTH: INVESTIGATION ON REDUCED OPERABILITY (CHIRO)
Research Area: Bone and Muscle Physiology
Expedition(s): 4
Principal Investigator(s): ● Paolo Pastacaldi, Hospital Santa Chiara, Pisa, Italy
● Valfredo Zolesi, Kayser Italia, Livorno, Italy
RESEARCH OBJECTIVES
Experiments on the upper limbs are becoming more significant in human spaceflight; being the
principal means of locomotion and fatigue can have a significant effect on the hand for ordinary
work and in particular for spacewalks. Crew’s Health: Investigation on Reduced Operability
(CHIRO) provides early data within a wide range of research on human upper limb behavior and
performances. The purpose of the experiment is to determine the influence of the microgravity
on the control of the grip force exerted by the hand or by a group of fingers and the adaptive
behavior of this control through long-term exposure to microgravity.
RESULTS
In general, a loss of motor control was
observed in the blind period of contraction
due to the absence of visual feedback; as
soon as the visual feedback was restored
(at the beginning of the final period), the
test subject tried again to reach the fixed
threshold, even if attempts were often
nullified by the arising muscle fatigue. The
weightlessness influenced the motor
control and the capability of keeping
muscle contraction constant was much
stressed. So the Static Effort, after an early
increase, recovered the initial values,
whereas the Root Mean Square was often
still increasing; this can lead to different hypothesis: a) the biomechanic system gain
(amplification factor) increases due to the absence of gravity; even if the stimuli to keep the
fixed force level are the same, the Root Mean Square of oscillations increases. b) the
biomechanic system gain does not change, but the stimuli is higher. Finally, the collected data
confirmed the increasing of Root Mean Square during the blind period of experiment
independently of weightless effects.
PUBLICATION(S)
Pastacaldi P, Orsini P, Bracciaferri F, et al. Short term microgravity effect on isometric hand grip
and precision pinch force with visual and proprioceptive feedback. Advances in Space Research.
January 2004;33(8):1368-1374. doi: 10.1016/j.asr.2003.09.040.
This investigation is complete and all results are published.
Astronaut Roberto Vittori uses the Hand Grip Dynamometer
on the International Space Station in 2002. ESA image.