Hand Posture Analyzer (HPA) - 11.22.16

Overview | Description | Applications | Operations | Results | Publications | Imagery

ISS Science for Everyone

Science Objectives for Everyone
Hand Posture Analyzer (HPA) examines the way hand and arm muscles are used differently during grasping and reaching tasks in weightlessness. Measurements are compared to those taken before and after flight to improve understanding of the effects of long-duration space flight on muscle fatigue.
Science Results for Everyone
Space travellers become monkey-like in space, using their hands and arms much more than they do back on Earth. This makes upper limb performance vital, especially on long-term missions.  The Hand Posture Analyzer investigation measures motion and force on hands, wrists, and forearms before and after space flight. The data were combined with that from other expeditions and a preliminary version of the same hardware used during an earlier mission to assess short- and long-term effects of weightlessness on upper limb performance. This could lead to better design of devices and tools used in space and may prove useful for treating injury and disease on Earth.

The following content was provided by Valfredo Zolesi, Ph.D., and is maintained in a database by the ISS Program Science Office.
Experiment Details


Principal Investigator(s)
Valfredo Zolesi, Ph.D., Kayser Italia Srl., Livorno, Italy

Paolo Pastacaldi, M.D., Hospital S. Chiara, Pisa, Italy
Federico Posteraro, M.D., Hospital Versilia, Lucca, Italy
Francesco Lacquaniti, M.D., University of Rome Tor Vergata, Rome, Italy

Italian Space Agency (ASI), Rome, Italy

Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)

Sponsoring Organization
Italian Space Agency (ASI)

Research Benefits
Information Pending

ISS Expedition Duration
April 2003 - April 2004; April 2005 - October 2005; October 2007 - April 2008

Expeditions Assigned

Previous Missions
CHIRO experiment in April 2002 during the taxi flight Soyuz TM34. Also performed during Increments 7 and 8.

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Experiment Description

Research Overview

  • The Hand Posture Analyzer (HPA) system is designed to collect kinematic and force data on human upper limbs (hands, wrists and forearms) onboard the International Space Station (ISS).

  • Kinematics is the science of motion. In human movement, it is the study of the positions, angles, velocities, and accelerations of body segments and joints during motion.

  • The kinematic studies on the movement of the hand and wrist in microgravity, collected while manipulating both virtual and concrete objects, is researched to assess the approaching, reaching, and grasping mechanics of the hand and fingers without the effect of gravity.

  • Also, a fatigue assessment of the forearm is done to determine how the control of grip force is affected by the exposure to weightlessness.

The Hand Posture Analyzer (HPA) examined how hand and arm muscles are used differently during grasping and reaching tasks in weightlessness by collecting kinematic and force data on astronaut’s upper limbs (hands, wrists and forearms). Three different sets of data were collected: preflight, in-flight and postflight. The measurements involved the crew member manipulating both virtual and concrete objects, is researched to assess the approaching, reaching, and grasping mechanics of the hand and fingers without the effect of gravity.

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Space Applications
This investigation provides information on performance modification of the muscular system during long stays in microgravity, and the characterization of motion strategies and postural behavior of the human body in weightlessness. Results may lead to the optimization of constructive criteria in the design of orbital modules, devices, and tools for use in space.

Earth Applications

Data from the investigation contribute to the development of new methods, protocols, and instruments for the study and treatment of upper limb problems on Earth.

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Operational Requirements and Protocols

The Mental Imagery of Gravity Effects on Object Motion investigation consists of bouncing an imaginary tennis ball off of the ceiling (overhead racks) in the Lab module and catching the ball. The initial position for holding the ball is with the arm straight down by the crewmembers side. To toss the ball, bend the arm approximately 90 degrees and release the ball. Imagine the speed with which the ball travels as it moves up to the ceiling of the module then returns to your hand. At the point in time that you think the ball would return to your hand, "catch" the ball and hold that position until the software prompts you to prepare for the next toss.

HPA operations consist of the hardware setup, performance of the four protocols, and the disassembly of the hardware.

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Decadal Survey Recommendations

Information Pending

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Results/More Information

The absence of gravity causes many inconveniences, generically referred to as “space motion sickness,” but collected data have shown crewmembers normally adapt to microgravity in about a week. The Hand Posture Analyzer (HPA) is the very first Italian Space Agency’s (ASI) facility conceived for the utilization on the International Space Station (ISS) and has been extensively used on long-term flight on increment 7 and 8 during 2003 and 2004. The main objective of HPA is the assessment of upper limbs performance, specifically the holding or grasping movements, and muscular function since the upper limbs are the principal means of work and locomotion onboard the space station. Daily tasks and movements, as well as physically demanding extra-vehicular activities, can have a significant effect on the hand causing muscle fatigue. This degradation of muscular-skeletal performance can be easily recognized on the upper limb. Another aspect is the adjustment of the brain and motor control system to microgravity on the upper limb, affecting not only bio-mechanics but in general the psycho-physical conditions. Overall, tests show prompt recovery after short-term flight and loss of force up to 40% after 6 months in space. These results provide a quantitative evaluation of the performance of the upper limb and provide the base to develop countermeasures (e.g., tools to facilitate adaptation and make working in space easier) against the impairments due to change in gravity. Also, the experience gained from these experiments can be applied for treatment of patients with local traumas or diseases of the Central Nervous System back on Earth.

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Results Publications

    Pastacaldi P, Orsini P, Bracciaferri F, Neri G, Porciani M, Liuni L, Zolesi V.  Short term microgravity effect on isometric hand grip and precision pinch force with visual and proprioceptive feedback. Advances in Space Research. 2004 January; 33(8): 1368-1374. DOI: 10.1016/j.asr.2003.09.040. [Also: Pastacaldi, P., P. Orsini, F. Bracciaferri, G. Neri, M. Porciani, L. Liuni, and others, ‘Short Term Microgravity Effect on Isometric Hand Grip and Precision Pinch Force with Visual and Proprioceptive Feedback’, COSPAR, F1.1-0013-02 (2002), 7pp. ]

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Ground Based Results Publications

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ISS Patents

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Related Publications

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Related Websites
ESA Human Spaceflight

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image NASA Image: - The Italian astronaut Roberto Vittori, from the Taxi Flight Soyuz TM34 in 2002, uses the hand grip dynamometer to test the muscle fatigue of the forearm.
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image Video Screen Shot of ISS Science Officer, Ed Lu, during ISS Expedition 7 performing the HPA activity. Image courtesy of NASA.
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image NASA Image ISS008E21614 - ISS Science Officer, Mike Foale performing the HPA investigation during Expedition 8, using the hand grip dynamometer to test the muscle fatigue of the forearm.
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image NASA Image ISS008E21605 - NASA Science Officer Mike Foale, during ISS Expedition 8 using hand/wrist position tracking via hand posture acquisition glove, during HPA operations.
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The pinch grip is also used for the muscle fatigue experiments in the Hand Posture Analyzer investigation. Image courtesy of ASI.

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