An ambulatory biomechanical data collection system for use in space: design and validation.
BACKGROUND
Loss in bone mineral density and muscle strength in astronauts following long-duration spaceflight have been well documented, but the altered force and movement environments in microgravity which may contribute to these changes have not been well characterized. This paper describes the instrumentation, software, and data collection procedures developed for the "Foot" experiment that was conducted on the International Space Station (ISS) to provide insight into the biomechanics of daily activity in a microgravity environment.


METHODS
The instrumentation used for data collection included the Ambulatory Data Acquisition System (ADAS), ADAS electromyography (EMG) modules, the Joint Excursion System, and the Total Force-Foot Ground interface system, which were all integrated into a specially designed Lower Extremity Monitoring Suit. There were 14 total channels of data that were collected at sampling rates between 8 Hz and 1024 Hz, including 7 channels of EMG, 4 channels of joint angle data, 2 channels of in-shoe ground reaction force, and a marker channel for event recording. Data were typically collected for between 6.5 and 11.8 h of activity during 4 d on Earth and 4-7 d in flight.


RESULTS
Exemplar data sets collected preflight on astronauts in 1 g to validate the instrumentation are presented.


CONCLUSIONS
We conclude that the system provides valid and useful biomechanical information on long-term activity. The analysis of data collected on-orbit using the system described here will be presented in a series of future papers characterizing the biomechanics of astronaut activity during complete working days on the Earth and on the ISS.
Cavanagh
Peter R
PR
Department of Orthopedics and Sports Medicine, University of Washington, Seattle, WA 98195-6500, USA. cavanagh@u.washington.edu
Gopalakrishnan
Raghavan
R
Rice
Andrea J
AJ
Genc
Kerim O
KO
Maender
Christian C
CC
Nystrom
Peter G
PG
Johnson
Micah J
MJ
Kuklis
Matthew M
MM
Humphreys
Bradley T
BT
D000328:Adult; D001696:Biomechanical Phenomena; D015519:Bone Density; D002138:Calibration; D003625:Data Collection / Q000379:methods*; D004576:Electromyography; D004867:Equipment Design; D015444:Exercise / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D013026:Space Flight; D019442:Space Suits