Exercise in space is a promising countermeasure to space flight-induced bone loss and muscle atrophy. Dr. Brian L. Davis is developing a dynamic exercise countermeasure device that permits a jumping exercise in space. The device benefits multiple physiological systems – muscular, skeletal, neurovestibular and cardiovascular – without transmitting vibrations and impact forces to other parts of the spacecraft.
Overview
Design and Validation of a Dynamic Exercise Countermeasure Device
Principal Investigator:
Brian L. Davis, Ph.D.
Organization:
The Cleveland Clinic Foundation
Technical Summary
Exercise in space is a promising countermeasure to spaceflight-induced bone loss and muscle atrophy. The objective of this study was to develop a dynamic exercise countermeasure device that permits a jumping exercise in space. The device benefits multiple physiological systems - muscular, skeletal, neurovestibular and cardiovascular - without transmitting vibrations and impact forces to other parts of the spacecraft.
This three-year project was divided into three phases. In Year 1, we collaborated with Foster Miller Inc., a company that has expertise in the design of both lightweight structures and vibration isolation methodology, to construct a device that permits dynamic jumping exercise in microgravity and that is suitable for the International Space Station.
In Year 2, we conducted ground-based studies in the exercise device to verify that muscle activation patterns are not compromised by the exercise device and that limb-loading data, as measured by forces experienced under the feet during jumping, are in the range that is believed to maintain the integrity of bone. Four different exercises were performed in the exercise device: 1) standard toe raises, 2) standard "squats", 3) "jumping rope" - in which consecutive mini-jumps were performed, and 4) maximum jumps - in which a series of maximum "vertical" jumps were performed. Test results are promising in that we have been able to demonstrate that subjects exercising in the Dynamic Exercise Countermeasure Device (DECD) experienced ground reaction forces ranging from 2-3 times bodyweight. These forces are greater than what is currently elicited by astronauts exercising in space. Jumping exercises may, therefore, prove to be a more effective countermeasure to spaceflight-induced deconditioning.
In Year 3, we confirmed the efficacy of the exercise device in true microgravity through experiments on the KC-135. Ground reaction forces were found to be at levels of high enough impact to provide an adequate daily loading stimulus to alleviate bone loss. With regard to muscle activity, results suggest that exercises in the DECD will stimulate higher muscular force requirements of certain muscle groups to better maintain overall muscle mass of the legs.
Earth Applications
The benefits of exercising the cardiovascular and musculoskeletal systems are widely accepted on Earth. Bone demineralization (bone mass loss) is a well-documented physiologic effect of long-duration spaceflight and as a consequence of disease and aging. Animal experiments on Earth have clearly indicated that: (1) certain bone strains and strain rates stimulate bone deposition, and (2) repetitive loading of the lower extremity can increase osteonal bone formation even as proximally as the vertebral column.
Such studies have also indicated that a relatively small number of appropriate weight-loading cycles may be sufficient to stimulate bone deposition. By extending the philosophy of designing exercise modalities that elicit high impact forces, a dynamic exercise countermeasure device (DECD) that utilizes jumping as the mode of exercise will benefit a large population on Earth. This includes developing exercise protocols for patients with osteoporosis. Many such exercise plans are used; however, jumping may provide a more efficient and less time consuming way to address issues decreasing bone loss.
An added benefit of the DECD is that it may aid patients with musculoskeletal disorders or traumatic injuries, which require rehabilitation therapy to strength and increase muscle mass to return to full function. This is due in part to substantial activity found in lower extremity muscles during the resistive exercise such as squats and toe raises. In this manner, the DECD could act in the same manner as gym/therapy equipment.
This project's funding ended in 2004