Abstract
Physical activity depends on the cardiorespiratory (CR) system’s ability to deliver energy to the muscles to sustain their action. The g loads of high-performance aircraft also put large stresses on the CR system. But in a matter of days to weeks, cardiorespiratory capacity, usually called aerobic fitness, is sharply reduced by lack of physical activity, whether on Earth, in bed rest or in weightlessness (Fig. 8.1).
This is a preview of subscription content, log in via an institution.
Buying options
Tax calculation will be finalised at checkout
Purchases are for personal use only
Learn about institutional subscriptionsNotes
- 1.
Activities that require large amounts of air.
- 2.
This is discussed in the section on measurements, p. 266.
- 3.
A notable exception to such activity was Neil Armstrong with his philosophy, “I have only so many heart beats, and I am not going to waste any running around a track.”
- 4.
There is no longer any question that health, especially cardiac health, can be improved by regular physical activity.
- 5.
Adenosine Triphosphate and Phosphocreatine.
- 6.
One of his heart valves was later repaired in the hospital.
- 7.
There are complex interrelations of CO2 and O2 uptake and release that would add little to our concerns.
- 8.
Vessels outside heart and lungs.
- 9.
It has been difficult to find valid studies of the increase in O2 uptake or increase in performance with the increase in hemoglobin concentration.
- 10.
A hallmark of aerobic athletes is their large chest (thorax).
- 11.
Some designations have been changed from clinical usage and waveforms corrected.
- 12.
Lower chambers of the heart are electrically insulated from the upper to maintain the trigger system’s control.
- 13.
Heart muscle is striated like the body’s somatic muscle, but it is also interconnected such that contraction of one fascicle insures contraction of the adjacent connected fascicles.
- 14.
This rate reduction with age is considered obligatory in cardiology, but exceptions are seen in some athletes.
- 15.
CO2 in water undergoes this reaction, producing hydrogen ions: CO2 + H2O → HCO− + H+.
- 16.
However human runners’ heart rate response is relatively crude to that of a trained horse whose total increase in rate occurs in one or two steps of starting and is appropriate to the gait selected.
- 17.
Accurate inexpensive EKG wristwatch monitors are readily available. Rate changes too rapidly with cessation of exercise for pulse rate to be accurate when counted after exercise has stopped.
- 18.
A total body exerciser in which the subject did rapid, full extension lifts was developed and tested including zero-g flights in 1966 for the USAF Manned Orbiting Laboratory (MOL) program. It could produce maximum oxygen intakes approximating those of running.
- 19.
“It is apparent that vast differences in scope and methodology, especially as regards the degree and duration of immobilization, make quantitative comparisons between [bed] rest studies difficult or impossible,” Brent Saltin.
- 20.
It is not unusual for a cardiac patient to be in shock from loss of infarcted muscle yet to walk out of the hospital a week later after the remaining muscle had increased in size and strength to carry the usual load.
- 21.
O2 consumption during 8 h sleep was assumed to be at BMR rate of 2.7 mL kg−1 min−1.
References
Lovelace R, et al. Selection and maintenance program for astronauts for the National Aeronautics and Space Administration. Aerosp Med. 1962;33:667–84.
Wilson C. Physical fitness tests. WADC-TR 59-505, p 49–64.
Berry C. Man’s response to long-duration spaceflight in the Gemini spacecraft. In: Gemini mid-program conference. MSC: Houston, TX. NASA SP–121, 25:135; 1966.
Rummel J, Savin C, Michel E. Exercise response. In: Biomedical results of Apollo. Washington, DC: NASA . NASA SP–368, 5:265; 1973.
Michel E, Rummel J, Sain C, Buderer C, Lem J. Metabolic activity. In: Results of Skylab medical experiment M171 1975. Washington, DC: NASA. NASA SP–377, 36:372–87; 1977.
Michel E, et al. Results of Skylab medical experiment 171-metabolic activity. In: Biomedical results from Skylab. Washington, DC: NASA. NASA SP–377; 1977.
Saltin B, et al. Maximal oxygen uptake in athletes. J Appl Physiol. 1967;23(63):353–8.
Guyton A, Hall J. Pulmonary ventilation. In: Textbook of medical physiology, 11th ed. Elsevier Inc., 37:471–80; 2006.
Guyton A, Hall J. Regulation of respiration. In: Textbook of medical physiology, 11th ed. Elsevier Inc, 41:514–22; 2006.
Wilson C. Treadmill stress test protocols. In: Social security advisory service physical fitness tests.
Cooper K. The aerobics way. Toronto: J. B. Lippincot; 1977.
Tikanen O. Muscle activity and inactivity periods during normal daily life. PLoS One. 2013;8(1):e52228.
Lee S, Moore AD, Everett ME, Stenger MB, Platts SH. Aerobic exercise deconditioning and countermeasures during bed rest. Aviat Space Environ Med. 2010;81(1):52–63.
Convertino V. Effects of deconditioning and reconditioning on aerobic power. In: Deconditioning and reconditioning. CRC Press LLC; 2004. p. 5.
Saltin B, Blomqvist G, Mitchell JH, Johnson RL Jr, Wildenthal K, Chapman CB. Response to exercise after bed rest and after training. Circulation. 1968;38(5 Suppl):VII1–78.
Shayler D. Disasters and accidents in manned spaceflight. Chichester: Praxis Publishing; 2000.
Sawin C. Extended duration orbiter medical project 1989–1995 NASA/SP-1999-534.
Moore AD, Lynn PA, Feiveson AH. The first 10 years of aerobic exercise responses to long-duration ISS flights. Aerosp Med Hum Perform. 2015;86(12):A78–86.
Moore AD, Downs ME, Lee SM, Feiveson AH, Knudsen P, Ploutz-Snyder L. Peak exercise oxygen uptake during and following long-duration spaceflight. J Appl Physiol. 2014;117(3):231–8.
Thornton W, Hoffler G, Rummel J. Anthropometric changes and fluid shifts. In: Biomedical results of Skylab, NASA Washington, DC, NASA SP–377, 32:330–338; 1977.
Kozlovskaya IB, Yarmanova EN, Yegorov AD, Stepantsov VI, Fomina EV, Tomilovaskaya ES. Russian countermeasure systems for adverse effects of microgravity on long-duration ISS flights. Aerosp Med Human Perform. 2015;86(12):A24–31.
Yarmanova EN, Kozlovskaya IB, Khimoroda NN, Fomina EV. Evolution of Russian microgravity countermeasures. Aerosp Med Hum Perform. 2015;86(12):A32–7.
Moore A, et al. Cardiovascular exercise. In: The US Space Program: past, present and future. Acta Astronaut. 2010;66:974–88.
Author information
Authors and Affiliations
Glossary
Glossary
Aerobic has to do with oxygen (in the air) consumption; e.g., aerobic exercise. Aerobic may now be used as a noun, such as in Ken Cooper’s system. Kenneth H. Cooper, M.D. introduced the concept of aerobics. He authored the 1968 book Aerobics, which emphasized a point system for improving the cardiovascular system. His points system is also the basis of the 10,000 steps per day method of maintaining adequate fitness by walking.
Aerobic fitness is the capacity of the cardiorespiratory system’s complex (Fig. 8.3) to use oxygen in converting energy into muscle activity.
Aerobic capacity is a measure of the cardiorespiratory system’s ability to provide oxygen to muscles, usually measured in terms of oxygen consumption expressed as liters per minute, L min−1, or milliliters per minute, mL min−1. This may be normalized for differing subject masses by dividing oxygen consumption by subject mass or mL min−1 kg−1, which is the usually preferred expression and used here whenever possible.
Cardiac Exercise Stress Test is one in which exercise is used to stress the heart, and is monitored by EKG, BP and other measurements. Respiratory measurements are not usually done.
Cardiorespiratory is more or less synonymous with aerobic.
Cardiorespiratory systems indicates the collection of systems that form the serial change that begins with intake of oxygen to forceful motion by muscle (Fig. 8.3). Note that the muscle mass may vary in location, but the other systems in the chain are fixed.
Maximum oxygen intake or MOI is the O2 consumed during a maximum effort at some task that uses large masses of muscle such as treadmill locomotion or cycle ergometry.
O 2 may be used for oxygen.
Oxygen consumption may also be expressed in terms of energy transformed per unit of time, joules or kilojoules per hour or minute; i.e., J h−1, kJ h−1 or kJ min−1 or J min−1. This may also be expressed as kilo calories per unit of time; i.e., cal h−1 or cal min−1. An approximate conversion factor to oxygen consumed is 5 cal = 1 L.
Oxygen uptake is a synonymous term for oxygen consumption.
pH is a figure expressing the acidity or alkalinity of a solution on a logarithmic scale on which 7 is neutral, lower values are more acid, and higher values more alkaline. The pH is equal to −log10c, where c is the hydrogen ion concentration in moles per liter.
Spirometer is a closed tank system that moves up or down according to the volume of gas in it.
Rights and permissions
Copyright information
© 2017 Springer International Publishing AG
About this chapter
Cite this chapter
Thornton, W., Bonato, F. (2017). Loss of Aerobic Capacity During Weightlessness. In: The Human Body and Weightlessness. Springer, Cham. https://doi.org/10.1007/978-3-319-32829-4_8
Download citation
DOI: https://doi.org/10.1007/978-3-319-32829-4_8
Published:
Publisher Name: Springer, Cham
Print ISBN: 978-3-319-32828-7
Online ISBN: 978-3-319-32829-4
eBook Packages: Physics and AstronomyPhysics and Astronomy (R0)