Design and Validation of a Dynamic Exercise Countermeasure Device

Investigators:

• Brian L. Davis, Ph.D.
• Guang H. Yue, Ph.D.
• David J. Hoadley, DipME

Introduction:

Bone demineralization is a well-documented physiologic effect of space flight. In 1-G, animal experiments have indicated that (i) certain bone strain and strain rates do simulate bone deposition, and (ii) repetitive loading of the lower extremity can increase osteonal bone formation even as proximally as the vertebral column. In a previous study, Exercise Countermeasures for Astronauts, the merits of performing jumping exercises in microgravity were investigated.

Purpose:

A countermeasure device is being built that will optimize bone deposition while keeping vibration effects below the standards set by NASA.

Method:

In the first year of the project, we are in collaboration with Foster Miller Inc., a company that has expertise in the design of both lightweight structures and vibration isolation methodology. Through this partnership, we are designing a device that will permit dynamic jumping exercises with forces large enough to promote bone deposition with minimal vibration effects. In the second year, the system will be tested using a zero gravity simulator that has been developed under NASA NAGW-5006. Specifically, we will verify that muscle activation patterns and limb loading data are similar to the results we have already obtained for tethered jumping in microgravity. In the final phase, we will confirm the efficacy of the Dynamic Exercise Countermeasure Device in true microgravity through KC-135 experiments.