Exercise

Monica V. Trevathan Education Specialist Human Health and Performance Johnson Space Center - NASA June 2, 2005 William E. Amonette, M.A., CSCS Astronaut Strength, Conditioning, and Rehabilitation Team Johnson Space Center - NASA

Web Seminar Objectives 1.Review physiology of bone remodeling 2.Discuss changes that occur in micro- gravity 3.Discuss Astronaut exercise programs 4.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)

Definitions 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.

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

Bone Remodeling 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.

Factors Affecting 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.

Bone and Astronauts During Spaceflight 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 (cont.) 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.) About 1% of total bone mass is lost per month. 12x faster than with osteoporosis.

Astronaut Strength and Conditioning 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.

Strength & 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 (cont.) Space Shuttle astronauts ISS crew members

Exercise on ISS Resistive Exercise (IRED)

Exercise on ISS Treadmill (TVIS)

Exercise on ISS Cycle Ergometer (CEVIS)

Post-Flight Reconditioning 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 (cont.) 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.

How do we prevent bone loss? 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 After the ages of 25-30, we can only flatten out the rate of decline of bone mass.

25-30

Bone loss can be thought of as saving for retirement.

Kids and Training * Forces measured during weightlifting can be 40x body weight.* Junior Olympic weightlifters (ages 15-17) have much greater BMD than age matched controls.

Kids and Training (cont.) They have greater BMD in the spine and femoral neck than adults between the ages of Greater bone BMD is likely due to the high force and rate of force production from weightlifting. * Forces measured during weightlifting can be 40x body weight.*

Kids and Training (cont.) 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. * Forces during landing from a jump in gymnastics are up to 16 times body weight.*

What does this mean for our Kids? 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.

How can you help NASA? Presidential initiative states that we will go to the planet Mars by the year 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.

Conclusion 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 (cont.) 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.

Related NASA Education Material National Space and Biomedical Research Institute Activities Guides for Teachers 5-8 grade

Related NASA Education Material NASA CONNECT™ Good Stress – Building Better Muscle and Bone Better Health from Space to Earth Grades 5-8

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

Monica V. Trevathan Education Specialist Johnson Space Center - NASA William E. Amonette, M.A., CSCS Astronaut Strength, Conditioning, and Rehabilitation Team Thank You!