Measurement of muscle actions and foot reaction forces from crew members during entire working days on the International Space Station (ISS)

We present pilot work in preparation for ISS Experiment 318, which will investigate changes in lower limb daily mechanical loading and muscular activity profiles that have been implicated in bone mineral loss and muscle atrophy during spaceflight. Prototype equipment for the musculo-skeletal rack of the Human Research Facility (HRF) was used in conjunction with the Ambulatory Data Acquisition System to record and store data. Right foot ground reaction force profiles, right leg EMG activity profiles from the tibialis anterior and vastus medialis, and joint angular excursion profiles from the right knee and ankle were collected during five minutes each of forward and backward running in Ig as well as over a twelve hour period of activities during daily living. Ground reaction force profiles were analyzed to provide an estimate of 1g daily mechanical load stimulus, while EMG and joint angle profiles characterized the role of individual muscles in generating and absorbing energy.