Practical Applications: Muscles and Exercise
Finally, it is important to note that while the NSBRI program in space life sciences is targeted at solving problems of human health and performance during space flight, there also are important problems to be addressed in the daily setting on Earth. Shown on the left side of the slide are two individuals with spinal cord injuries. Both subjects have marked atrophy of the lower legs because the lesions were encountered in the spinal cord between the waist and the shoulders. The individual in the top left figure uses the upper extremities only for getting from one place to another, whereas the individual in the lower left figure is an avid endurance exercise athlete. By performing a high volume of exercise, this individual not only has developed large muscles in the arms and shoulders, but bone scans show that this individual has bones with a high mineral density and size. This suggests that increased physical activity involving a high level of muscular involvement is essential to maintain bone mass and mineral density.
The idea that increased physical activity is of benefit also holds true for the individuals in the middle figures. People who live a very active life are able to maintain their muscle mass and youthful body structure, as opposed to those who maintain a sedentary lifestyle that eventually leads to frailty. While we think of physical activity as essential for athletes, it is important to remember that one’s quality of life depends upon how much effort we put into taking care of our bodies. Thus, as new findings are demonstrating, sound bodies and sound minds are dependent on an active lifestyle. The question is, how do you presently take care of yourself? Do you think you are doing the right things to keep you fit? Research evolving from the space program should provide a prescription for keeping yourself active. Are you up to the challenge?
Rittweger, J., Frost, H. M., Schiessl, H., et al. (2004). Muscle atrophy and bone loss after 90 day bedrest and the effects of flywheel resistive exercise and pamidromate: results from the LTBR study. J. Bone 11: 014-033.
Clasey, J. L., Janowiak, A. L., Gater, D.R. (2004). Relationship between regional bone density measurements and the time since injury in adults with spinal cord injuries. Arch Phys Med Rehab 85: 59-64.
Shackelford, L. C., LeBlanc, A. D., Driscoll, T. B, et al. (2004). Resistance exercise as a countermeasure to disuse-induced bone loss. J. Appl. Physiol. 97: 119-129.
ADDITIONAL NOTES FROM SPEAKER’S TRANSCRIPT (http://www.bioedonline.org/presentations/) The individual on the upper left of the slide has had a spinal injury. This individual has to be maintained in a wheelchair for locomotion. If you looked at his leg muscles, they would be small. And his bone would be relatively small and demineralized. The individual on the bottom left of the slide competes in wheelchair marathons. And while the muscles below the lesion (somewhere between the waist and shoulders) are small, and the bone in his legs has been demineralized, you see in the upper torso, by this individual putting a lot of stress on his arms by wheeling, the arms and chest have become extremely well developed. The bone mass is greater, and if you looked at the bone mass in this person’s spinal column, it also would be greater than in the individual at the top left. So we know that by exerting muscle and putting more muscle stress on bone, and keeping our muscles very active, we can impact bone health. This is important as individuals get older, especially women who experience osteoporosis, which is very common. If we look at the center part of the slide, the individual in the top image is experiencing the number one disease in the world. Every human being is faced with this disease, Sarcopenia, or atrophy and wasting of the muscle fibers. The individual on the bottom has led a very active life, and has used a heavy resistance weight training program. While these two individuals are the same age, the body structure speaks for itself. Which individual would you like to emulate in this aging process? Finally, the resistance training paradigms paradigms we are designing for astronauts can help athletes to be much fitter and more competitive. So the science we are conducting for the space program has obvious spin-offs that can impact a broad range of people in the general population. And as I close, I ask, how do you want to age? Do you want to age with a lot of pizzazz, or do you want to become a couch potato?
- iStockphoto. Atrophy of legs # 177380.
- iStockphoto. Man lifting weights # 3644853.
- iStockphoto. Spinning for Fitness at 50 plus # 2275868 .
- Axelson, P. Racing wheelchairs. US Department of Transportation, Federal Highway Administration. Retrieved 08-06-2007 from www.tfhrc.gov/safety/pubs/04103/03.htm
- iStockphoto. Back of wheelchair # 2514311.
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