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Exercise. Web Seminar Objectives Review physiology of bone remodeling Discuss changes that occur in micro-gravity Discuss Astronaut exercise programs Discuss the importance of exercise. Human Body as an Automobile. Brain is the computer of the system Motor and drive train are the muscles
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Web Seminar Objectives Review physiology of bone remodeling Discuss changes that occur in micro-gravity Discuss Astronaut exercise programs Discuss the importance of exercise
Human Body as an Automobile • Brain is the computer of the system • Motor and drive train are the muscles • Bone is the chassis (frame)
Bone Mass – The total amount of bone. Bone Mineral Density (BMD) - The amount of bone in a given area of space. Bone Strength – The breaking strength of a bone. Factors in density, mass, and the structural make-up of the bone. Definitions
Osteoblasts – cuboidal cells that synthesize components of bone matrix and are also responsible for the production of new bone. Osteoclasts – multinucleated (50 + nuclei) bone cells that dissolve bone matrix. Definitions
Types of Bone Cortical bone (compact) / Trabecular bone (spongy)
Wolf’s Law: “As bones are subjected to stress demands in weight bearing posture, they will model or alter their shape accordingly.” Journal of Subluxation Research
Ongoing process that happens throughout life. Osteoclasts remove bone, and osteoblasts come in behind the osteoclasts and lay down new bone. The bone quantity of the adult skeleton may be replaced in 5 years. Process is not uniform throughout the skeleton. Bone Remodeling
Activity Level Age Force on bone Compression (impact) Torsion (twisting) Strain (pulling) Shear Rate of Force Development Volume of Impacts Diet (calcium & Vitamin D) Etc. Factors Affecting Bone Remodeling
Bone begins to remodel in as little as 3 days of microgravity. Over-time the changes in bone resorption result in losses of bone mineral density (BMD) and strength. Bone and Astronauts During Spaceflight
The magnitude of changes are not uniform, and seem to occur faster in trabecular (spongy) bone than coritcol (compact) bone. The changes occur faster in load-bearing bones. Bone and Astronauts During Spaceflight (cont.)
Changes are specific to load bearing sites of the skeleton, most dramatically in the Calcaneous (heel bone), Femoral neck, Lumbar spine, and Pelvis. Bone and Astronauts During Spaceflight (cont.)
Bone and Astronauts During Spaceflight (cont.) • About 1% of total bone mass is lost per month. 12x faster than with osteoporosis.
Exercise is the most promising countermeasure for microgravity related bone loss. Astronauts perform exercise: Pre-spaceflight During-spaceflight Post spaceflight Astronaut Strength and Conditioning
Exercise programs are designed to develop or maintain: bone mineral density, aerobic and anaerobic capacity, strength, power, and local muscle endurance. Astronaut Strength and Conditioning
Structured program begins 6-months prior to shuttle flights and 1-year prior to ISS flights. Two-hours per day 2-3 times per week is scheduled for exercise preflight, but adjusted if there are other training requirements. Strength & Conditioning
Space Shuttle astronauts ISS crew members Strength & Conditioning (cont.)
Exercise on ISS Resistive Exercise (IRED)
Exercise on ISS Treadmill (TVIS)
Exercise on ISS Cycle Ergometer (CEVIS)
After long duration flight, astronauts go through a 45-day reconditioning program. The program is progressive and it involves a number of variables. Post-Flight Reconditioning
Purpose – to safely return to activities of daily living as soon as possible. Within the 45 days strength, power, flexibility, and aerobic and anaerobic capacity are usually restored. Loses in bone mineral density may take more than 2 years to restore. Post-Flight Reconditioning (cont.)
The number one preventative measure is to achieve high levels of peak bone mass early in life. Peak bone mass is achieved between the ages of 25-30. After the ages of 25-30, we can only flatten out the rate of decline of bone mass. How do we prevent bone loss?
Bone loss can be thought of as saving for retirement.
Kids and Training • Junior Olympic weightlifters (ages 15-17) have much greater BMD than age matched controls. * Forces measured during weightlifting can be 40x body weight.*
They have greater BMD in the spine and femoral neck than adults between the ages of 25-30. Greater bone BMD is likely due to the high force and rate of force production from weightlifting. Kids and Training (cont.) * Forces measured during weightlifting can be 40x body weight.*
Junior gymnasts (7-8 yrs. old) have greater BMD in load bearing sites of the sport. The magnitude of changes appear to be related to volume of training. Kids and Training (cont.) * Forces during landing from a jump in gymnastics are up to 16 times body weight.*
BMD is affected by activities that involve impact loading. Any sport or other physical activity involve impact loading. BMD can be enhanced in children as young as 7 and they should remain active throughout life to prevent low bone mass later in life. What does this mean for our Kids?
How can you help NASA? • Presidential initiative states that we will go to the planet Mars bythe year 2030. • Astronauts with low bone mass will likely be disqualified for a Mars mission.
How can you help NASA? (cont.) • Potential astronauts for a Mars mission are likely in grades 5-8 right now. • If your desire is to be a long duration astronaut, you must be attaining high levels of bone mass now.
Bone remodeling is a process that continues throughout life and is affected by daily activities and exercise. Astronauts who go to space lose BMD at a rate 12x faster than osteoporotic humans on Earth. NASA implements exercise pre-, during-, and post-spaceflight to minimize loss of bone. Conclusion
Number one preventative measure for diseased levels of bone mass is exercise early in life. BMD can be enhanced in children as young as 7 and they should remain active throughout life to prevent low bone mass later in life. Conclusion (cont.)
National Space and Biomedical ResearchInstitute Activities Guides for Teachers5-8 grade Related NASA Education Material http://www.nsbri.org/Education/index.html
NASA CONNECT™ Related NASA Education Material • Good Stress – Building Better Muscle and Bone • Better Health from Space to Earth • Grades 5-8 http://connect.larc.nasa.gov
Related NASA Explores Articles • “Flying Fit” • “Muscle-bound Research” • “Use It Or Lose It!” • Articles and lessons for:K-4, 5-8, 9-12 grades http://www.nasaexplores.com
Thank You! William E. Amonette, M.A., CSCS Astronaut Strength, Conditioning, and Rehabilitation Team Monica V. Trevathan Education Specialist Johnson Space Center - NASA