With respect to muscle Contraction Speed (ability to change force intensity with the time) for
long-duration astronauts, contraction speed decreased in the global time window by up to 45%
across the mission for the hand grip tests but with no significant difference in the pinch force
tests. This was probably correlated with the same factors involved in the Maximum Voluntary
Contraction decrease for handgrip measurements.
In weightless conditions, the force level control and the maintenance of constant force level
improved, however for higher target level (75% of Maximum Voluntary Contraction), the
muscular fatigue effects were evident. This effect is predominant and more evident in
weightlessness, probably dependent on the same physiological factors involved in the
Maximum Voluntary Contraction decrease for handgrip measurements. Proprioceptive
feedback seems to produce better results in weightless conditions.
PUBLICATION(S)
Pacelli F, Paoli A, Zolesi V, Norfini A, Donati A, Reggiani C. Implementation and ground
validation of a facility for functional and structural analysis of proximal upper limb muscles in
microgravity. Basic Applied Myology. 2009;19(2-3):77-86.
Zolesi V, Norfini A, Neri G. Hand Posture Analyzer: A facility for the study of the human upper
limb on the ISS. 54 th IAC Conference. doi: 10.2514/6.IAC-03-G.P.15.
This investigation is complete and all results are published.