Treadmill exercise within lower body negative pressure
Gravity on Earth helps to keep the human body in condition by placing a force or load on the body. Recent calculations suggest that all exercise in space to date has lacked sufficient load to maintain bone and muscle at the same level as before flight. Although ISS crews exercise for about 2 hours per day to prevent bone and muscle loss, their bungee-cord loading apparatus is too uncomfortable to generate loads over 60-70% of total body weight. Furthermore, the stimulus provided by blood pressure in the feet is abnormally low. It seems that, on Earth, variations in blood pressure around the body have a strong influence on muscular and skeletal tissue systems.
(NASA), equipped with bungee-cord loading
apparatus and exercising on the treadmill in
the Zvezda Service Module on the International
Space Station. 12 April 2004. (Image: NASA)
Separate studies have shown that using both the Lower Body Negative Pressure (LBNP)Chamber and the Flywheel Resistance Exercise Device reduced the adverse effects on the body during prolonged bed rest. These separate findings strongly document the need for a combination of resistive exercise and LBNP treadmill exercise to maintain bone, muscle, exercise capacity and cardiovascular function in space. In addition this combination exercise should help to prevent loss of coordination between the nervous system and the muscles following bed rest, which can also affect motion and balance.
Treadmill (Image: A. Hargens )
What is it good for?
The long-term objective of this research is to test exercise, which imposes a load on the body within a LBNP chamber together with high intensity resistance exercise to maintain systems of the body during long-term exposure to simulated weightlessness.
It is believed that the development of this combined countermeasure will provide: 1) stress on the body, which allows it to function closer to its level on Earth when compared to other countermeasures previously proposed for long-duration space flight, 2) sufficient and comfortable loading on the body to maintain the structure and function of muscular and skeletal tissues and other tissues of the body 3) a safe, cost effective, time efficient, low power, small mass and small volume alternative to artificial gravity by centrifugation. Centrifugation is another countermeasure under investigation for future simulation studies of spaceflight.
The training times for the combined LBNP with treadmill and flywheel exercise device are significantlyless than those currently used for long-duration spaceflight. Furthermore, the exercise concept allows for comfortable loading on the body greater than one body weight as well as normalising the blood pressure variations over the body, similar to upright posture on Earth.
How is it done?
The exercise group within the study will undertake a regimen of 40 minutes of treadmill running in an LBNP Chamber at 1-1.2 body weights followed by 10 min of static Lower Body Negative Pressure (3-4 times per week). This will be combined with less frequent, high resistance flywheel exercise, 2-3 times per week.
Volunteer using flywheel resistance exercise device. MEDES Space Clinic (Image: ESA/M. Specht)
UCSD Medical Center
University of California
San Diego
California, USA
Ball State University,
Muncie
Indiana, USA