Using dynamic foot stimulation during space flight as a countermeasure to muscle degradation

The degradation of muscle function and control that is associated with long-duration space flight potentially has negative operational and health consequences for the crew. This degradation is generally thought to stem from muscle atrophy and modifications in neuromuscular functioning that impede the ability to produce appropriate levels of force within a given time frame to accomplish a task-specific movement goal. Current approaches designed to counter muscle atrophy require extensive commitment of crew time, and are not completely effective. We propose the use of dynamic foot stimulation during long-duration spaceflight to "drive" lower limb neuromuscular activation and thereby attenuate muscle decline. This complementary addition to more traditional countermeasures is designed to implement the well-established motor control principle that sensory input can be used to modify the amount of neuromuscular activation. Our paper will discuss surface EMG data obtained from several crewmembers who flew aboard the Russian Mir space station and participated in a protocol that employed static foot stimulation during rapid arm movements. Additionally, the results of more recent ground-based research utilizing dynamic foot stimulation during various movements and the potential for this technology to be used as an in-flight countermeasure will be discussed.