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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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All sourcesNASA NTRSDOE OSTI
NASA NTRS2010

A Constant-Force Resistive Exercise Unit

A constant-force resistive exercise unit (CFREU) has been invented for use in both normal gravitational and microgravitational environments. In comparison with a typical conventional exercise machine, this CFREU weighs less and is less bulky: Whereas weight plates and associated bulky supporting structures are used to generate resistive forces in typical conventional exercise machines, they are not used in this CFREU. Instead, resistive forces are generated in this CFREU by relatively compact, lightweight mechanisms based on constant-torque springs wound on drums. Each such mechanism is contained in a module, denoted a resistive pack, that includes a shaft for making a torque connection to a cable drum. During a stroke of resistive exercise, the cable is withdrawn from the cable drum against the torque exerted by the resistance pack. The CFREU includes a housing, within which can be mounted one or more resistive pack(s). The CFREU also includes mechanisms for engaging any combination of (1) one or more resistive pack(s) and (2) one or more spring(s) within each resistive pack to obtain a desired level of resistance.

Colosky, Paul↗
NASA NTRS2007

Advanced Resistive Exercise Device

The advanced resistive exercise device (ARED), now at the prototype stage of development, is a versatile machine that can be used to perform different customized exercises for which, heretofore, it has been necessary to use different machines. Conceived as a means of helping astronauts and others to maintain muscle and bone strength and endurance in low-gravity environments, the ARED could also prove advantageous in terrestrial settings (e.g., health clubs and military training facilities) in which many users are exercising simultaneously and there is heavy demand for use of exercise machines.

Raboin, Jasen↗
NASA NTRS2011

Oxygen Uptake Responses to Submaximal Exercise Loads Do Not Change During Long-Duration Space Flight

In previous publications we have reported that the heart rate (HR) responses to graded submaximal exercise tests are elevated during long-duration International Space Station (ISS) flights. Furthermore, the elevation in HR appears greater earlier, rather than later, during the missions. A potential confounder in the interpretation of HR results from graded exercise tests on ISS is that the cycle ergometer used (CEVIS) is vibration-isolated from the station structure. This feature causes the CEVIS assembly to sway slightly during its use and debriefing comments by some crewmembers indicate that there is a "learning curve" associated with CEVIS use. Therefore, one could not exclude the possibility that the elevated HRs experienced in the early stages of ISS missions were related to a lowered metabolic efficiency of CEVIS exercise that would raise the submaximal oxygen uptake (VO2) associated with graded exercise testing work rates.

Moore, Alan D., Jr.↗
NASA NTRS2014

Temporal Changes in Left Ventricular Mechanics: Impact of Bed Rest and Exercise

The use of more sensitive and specific echocardiographic techniques such as speckle tracking imaging may address the current limitations of conventional cardiac imaging techniques to provide insight into the extent and time course of cardiac deconditioning following spaceflight or headdown tilt bed rest (HDTBR). METHODS Speckle tracking assessment of longitudinal, radial, and circumferential strain and twist was used to evaluate the impact of 70 days of HDTBR (n=7) and HDTBR + exercise (n=11) on temporal changes in LV mechanics. Echocardiograms were performed pre (BR‐2), during (BR31, 70), and following (BR+4hr) HDTBR. Repeated measures ANOVA was used to evaluate the effect of HDTBR on cardiac variables in control and exercise subjects. RESULTS After sedentary HDTBR, longitudinal (‐19.0 +/- 1.8% vs. ‐14.9 +/- 2.4%) and radial (15.0 +/- 1.9% vs. 11.3 +/- 2.2%) strain and twist (18.0 +/- 4.0deg vs. 17.0 +/- 3.6deg) were significantly impaired. In contrast, exercise preserved LV mechanics, and there were non‐significant improvements from BR‐2 to BR70 in longitudinal strain (‐18.7 +/- 1.5% vs. ‐20.4 +/- 2.7%), radial strain (13.2 +/- 2.4% vs. 14.2 +/- 1.6%), and twist (16.3 +/- 3.6deg vs. 18.6 +/- 5.9deg). CONCLUSIONS Using speckle tracking echocardiography provides important new insights into temporal changes in LV mechanics during disuse and exercise training.

Scott, J. M.↗
NASA NTRS2014

Transit Reconfigurable Exerciser - Intern Exit Abstract

The Transit Resistive Exerciser (TREX) was developed during a 16 week period in which a clutch device filled with smart material was built and began the testing phase. The clutch serves as a passive method of creating resistance. When paired with a series of springs, the device creates a rowing machine also capable of resistive exercise configurations. The device has loading profiles similar to the exercise devices used on the International Space Station today. The prototype created was designed in a modular fashion to support parallel development on various aspects of the project. Hardware and software are currently in development and make use of commercially available parts. Similar technologies have been used in the automotive industry but have never been explored in the context of countermeasure systems for space flight. If the work done leads to successful testing and further development, this technology has the potential to cut the size and weight of exercise devices by an order of magnitude or more.

Gebara, Christine A.↗
NASA NTRS2014

Temporal Changes in Left Ventricular Mechanics: Impact of Bed Rest and Exercise

BACKGROUND Current techniques used to assess cardiac function following spaceflight or head-down tilt bed rest (HDTBR) involve invasive and time consuming procedures such as Swan-Ganz catheterization or cardiac magnetic resonance imaging. An alternative approach, echocardiography, can monitor cardiac morphology and function via sequential measurements of left ventricular (LV) mass and ejection fraction (EF). However, LV mass and EF are insensitive measures of early (subclinical) cardiac deconditioning, and a decrease in LV mass and EF become evident only once significant deconditioning has already occurred. The use of more sensitive and specific echocardiographic techniques such as speckle tracking imaging may address the current limitations of conventional cardiac imaging techniques to provide insight into the magnitude and time course of cardiac deconditioning. METHODS Speckle tracking assessment of longitudinal, radial, and circumferential strain and twist was used to evaluate the impact of 70 days of HDTBR (n=7) and HDTBR + exercise (n=11) on temporal changes in LV mechanics. Echocardiograms were performed pre (BR-2), during (BR31, 70), and following (BR+4hr) HDTBR. Multi-level modeling was used to evaluate the effect of HDTBR condition (Control, Exercise) on cardiac variables. RESULTS Compared to BR-2, longitudinal (BR-2: - 19.0 +/- 1.8%; BR31: -15.9 +/- 2.4%; BR70: -14.9 +/- 2.4%; BR+4hr: -16.0 +/- 2.1%) and radial (BR-2: 15.0 +/- 1.9%; BR31: 12.3 +/- 2.4%; BR70: 11.3 +/- 2.2%; BR+4hr: 13.5 +/- 2.5% ) strains were significantly impaired during and following bed rest (p<0.05), while twist (BR-2: 18.0 +/- 4.0deg; BR31: 18.1 +/- 3.8deg; BR70: 17.0 +/- 3.6deg; BR+4hr:18.1 +/- 4.3deg) was significantly decreased at BR70 (p<0.05). In contrast, exercise preserved LV mechanics for longitudinal strain (BR-2: -19.1 +/- 1.5%; BR 31: -19.0 +/- 2.4%; BR70: -19.1 +/- 2.7%; BR+4hr: -17.8 +/- 2.1%), radial strain (BR-2: 13.8 +/- 2.4; BR31: 14.7 +/- 2.4; BR70: 14.4 +/- 1.6; BR+4hr: 14.4 +/- 2.4), and twist (BR-2: 17.8 +/- 3.6deg; BR31: 18.0 +/- 3.6deg; BR70: 18.2 +/- 5.9deg; BR+4hr: 18.3 +/- 4.2deg). CONCLUSIONS Speckle-tracking echocardiography provides important new insight into temporal changes in LV mechanics during disuse and exercise training.

Scott, Jessica M.↗
NASA NTRS2015

Computational Modeling Using OpenSim to Simulate a Squat Exercise Motion

Long duration space travel to destinations such as Mars or an asteroid will expose astronauts to extended periods of reduced gravity. Astronauts will use an exercise regime for the duration of the space flight to minimize the loss of bone density, muscle mass and aerobic capacity that occurs during exposure to a reduced gravity environment. Since the area available in the spacecraft for an exercise device is limited and gravity is not present to aid loading, compact resistance exercise device prototypes are being developed. Since it is difficult to rigorously test these proposed devices in space flight, computational modeling provides an estimation of the muscle forces, joint torques and joint loads during exercise to gain insight on the efficacy to protect the musculoskeletal health of astronauts.

Human Factors Engineering↗
NASA NTRS2015

Full Body Loading for Small Exercise Devices Project

Protecting astronauts' spine, hip, and lower body musculoskeletal strength will be critical to safely and efficiently perform physically demanding vehicle egress, exploration, and habitat building activities necessary to expand human presence in the solar system. Functionally limiting decrements in musculoskeletal health are likely during Mars proving-ground and Earth-independent missions given extended transit times and the vehicle limitations for exercise devices (low-mass, small volume). Most small exercise device concepts are designed with single-cable loading, which inhibits the ability to perform full body exercises requiring two-point loading at the shoulders. Shoulder loading is critical to protect spine, hip, and lower body musculoskeletal strength. We propose a novel low-mass, low-maintenance, and rapid deploy pulley-based system that can attach to a single-cable small exercise device to enable two-point loading at the shoulders. This attachment could protect astronauts' health and save cost, space, and energy during all phases of the Journey to Mars.

Downs, Meghan↗
NASA NTRS2017

Designing for Reliability and Robustness in International Space Station Exercise Countermeasures Systems

As spaceflight durations have increased over the last four decades, the effects of microgravity on the human body have become far better understood, as have the exercise countermeasures. Through use of a combination of aerobic and resistive exercise devices, today's astronauts and cosmonauts are able to partially counter the losses in muscle strength, aerobic fitness, and bone strength that otherwise might occur during their missions on the International Space Station (ISS). Since 2000, the ISS has employed a variety of exercise equipment used as countermeasures to these risks. Providing reliable and available exercise systems has presented significant challenges due to the unique environment. In solving these, lessons have been learned that can inform development of future systems.

Moore, Cherice↗
NASA NTRS2018

Virtual Exercise Training Software System

The purpose of this study was to develop and evaluate a virtual exercise training software system (VETSS) capable of providing real-time instruction and exercise feedback during exploration missions. A resistive exercise instructional system was developed using a Microsoft Kinect depth-camera device, which provides markerless 3-D whole-body motion capture at a small form factor and minimal setup effort. It was hypothesized that subjects using the newly developed instructional software tool would perform the deadlift exercise with more optimal kinematics and consistent technique than those without the instructional software. Following a comprehensive evaluation in the laboratory, the system was deployed for testing and refinement in the NASA Extreme Environment Mission Operations (NEEMO) analog.

Vu, L.↗
NASA NTRS1997

Pre-exercise hypervolemia and cycle ergometer endurance in men

Time to exhaustion at 87-91% of peak VO2 was measured in 5 untrained men (age: 31 +/- 8 years, body mass: 74.20 +/- 16.50 kg, body surface area: 1.90 +/- 0.24 m2, peak VO2: 2.87 +/- 0.40 l min-1, plasma volume: 3.21 +/- 0.88 l; means +/-SD) after consuming nothing (N) or two fluid formulations (10 ml kg-1, 743 +/- 161 ml): Performance 1 (P1), a multi-ionic carbohydrate drink, containing 55 mEq l-1 Na+, 4.16 g l-1 citrate, 20.49 g l-1 glucose, and 365 mOsm kg-1 H2O, and AstroAde (AA), a sodium chloride-sodium citrate hyperhydration drink, containing 164 mEq l-1 Na+, 8.54 g l-1 citrate, <5 mg l-1 glucose, and 253 mOsm kg-1 H2O. Mean (+/-SE) endurance for N, P1 and AA was 24.68 +/- 1.50, 24.55 +/- 1.09, and 30.50 +/- 3.44 min respectively. Percent changes in plasma volume (PV) from -105 min of rest to zero min before exercise were -1.5 +/- 3.2% (N), 0.2 +/- 2.2% (P1), and 4.8 +/- 3.0% (AA; P < 0.05). The attenuated endurance for N and P1 could not be attributed to differences in exercise metabolism (VE, RE, VO2) from the carbohydrate or citrate, terminal heart rate, levels of perceived exertion, forehead or thigh skin blood flow velocity, changes or absolute termination levels of rectal temperature. Thus, the higher level of resting PV for AA just before exercise, as well as greater acid buffering and possible increased energy substrate from citrate, may have contributed to the greater endurance.

NASA Center ARC↗
NASA NTRS1997

Resistance exercise prevents plantar flexor deconditioning during bed rest

Because resistance exercise (REX) and unloading induce opposing neuromuscular adaptations, we tested the efficacy of REX against the effects of 14 d of bed rest unloading (BRU) on the plantar flexor muscle group. Sixteen men were randomly assigned to no exercise (NOE, N = 8) or REX (N = 8). REX performed 5 sets x 6-10 repetitions to failure of constant resistance concentric/eccentric plantar flexion every other day during BRU. One-repetition maximum (1RM) strength was tested on the training device. The angle-specific torque-velocity relationship across 5 velocities (0, 0.52, 1.05, 1.75, and 2.97 rad.s-1) and the full range-of-motion power-velocity relationship were assessed on a dynamometer. Torque-position analyses identified strength changes at shortened, neutral, and stretched muscle lengths. Concentric and eccentric contractile work were measured across ten repetitions at 1.05 rad.s-1. Maximal neural activation was measured by surface electromyography (EMG). 1RM decreased 9% in NOE and improved 11% in REX (P < 0.05). Concentric (0.52 and 1.05 rad.s-1), eccentric (0.52 and 2.97 rad.s-1), and isometric angle-specific torques decreased (P < 0.05) in NOE, averaging 18%, 17%, and 13%, respectively. Power dropped (P < 0.05) in NOE at three eccentric (21%) and two concentric (14%) velocities. REX protected angle-specific torque and average power at all velocities. Concentric and eccentric strength decreased at stretched (16%) and neutral (17%) muscle lengths (P < 0.05) in NOE while REX maintained or improved strength at all joint positions. Concentric (15%) and eccentric (11%) contractile work fell in NOE (P < 0.05) but not in REX. Maximal plantar flexor EMG did not change in either group. In summary, constant resistance concentric/eccentric REX completely prevented plantar flexor performance deconditioning induced by BRU. The reported benefits of REX should prove useful in prescribing exercise for astronauts in microgravity and for patients susceptible to functional decline during bed- or chair-bound hospital stays.

NASA Discipline Musculoskeletal↗
NASA NTRS2025

Astronaut Physiological Deconditioning and Exercise Prescription Countermeasures in Spaceflight

The human skeletal muscular and cardiovascular systems are adapted to the upright posture of Earth’s gravitational environment. Astronauts experience an altered gravity environment in spaceflight that leads to a number of physiological changes and decrements to these systems that can decrease overall crew performance. Countermeasures, including prescribed exercise during spaceflight, is vital for astronauts to maintain optimal health and performance. The degree of physiological deconditioning is dependent on a multitude of factors such as sex, age, mission duration, fitness level, and gravity environments experienced. Deconditioning begins immediately upon entering an altered gravity environment and physiological decrements of the skeletal muscular and cardiovascular systems are measurable among astronauts within a few days. Thus, to maintain their physical fitness, ability to perform mission duties, and be able to egress vehicles when needed, it is imperative that astronauts participate in exercise during all phases of flight. This is especially important for long duration flights where deconditioning effects can be more deleterious. The NASA Office of the Chief Health and Medical Officer 3001 Standards Team develops requirements utilized by commercial and international partners to better understand spaceflight-induced physiological changes and countermeasures and expected outcomes with or without exercise.

exercise physiology↗
NASA NTRS1971

Cardiocirculatory responses to exercise - Physiologic study by noninvasive techniques.

The changes from rest to exercise were determined for certain phases of the cardiac cycle in ten healthy male subjects who underwent submaximal, physiologically paced bicycle ergometry. ECGs, phonocardiograms, and carotid pu lse tracings were recorded. The preejection period and isovolumic contraction time decreased with exercise. Changes in left ventricular ejection time appeared to depend on the severity or the duration of stress. Pulse transmission time did not change significantly. The data obtained in the study and comparison of these results to those obtained by invasive methods indicate that noninvasive techniques, when used in the manner suggested, are appropriate means for detecting a variety of cardiocirculatory changes during exercise.

Pigott, V. M.↗
NASA NTRS1972

Disproportional changes in hematocrit, plasma volume, and proteins during exercise and bed rest.

The interrelationships between the changes in plasma volume, hematocrit, and plasma proteins during muscular exercise and bed rest were investigated. Proportionally, the changes in hematocrit are always smaller than the changes in plasma volume. For this reason changes in the concentration of blood constituents can only be quantitated on the basis of plasma volume changes. During short periods of intensive exercise, there was a small loss of plasma proteins. With prolonged submaximal exercise there was a net gain in plasma protein, which contributes to stabilization of the vascular volume. Prolonged bed rest induced hypoproteinemia; this loss of plasma protein probably plays an important role in recumbency hypovolemia.

Van Beaumont, W.↗
NASA NTRS1972

Cardiorespiratory responses to exercise in air and underwater.

Respiratory gas exchange, end-tidal gas tensions, alveolar ventilation, respiratory frequency, cardiac output, and pulse rate were measured in four healthy adult males at rest and during mild and moderate exercise in air at 18-22 C and underwater at 35.0-35.5 C. Immersion was associated with a 10% increase in pulse rate and cardiac output at all levels of exercise. There were no changes in end-tidal CO2 tension or alveolar ventilation. It is concluded that horizontal subjects breathing at eupneic pressures and working against mild and moderate loads in warm water show the same responses to exercise as in air.-

Denison, D. M.↗
NASA NTRS1973

Blood electrolytes and exercise in relation to temperature regulation in man

Current knowledge and theories about the relation of blood electrolytes and exercise to thermoregulation in man are reviewed. It is shown that the elevation of body temperature during physical exercise is a regulated process and is not due to a failure of the heat dissipating mechanisms. Core and skin temperatures do not provide sufficient information to account for the control of sweating during exercise. Evidence is presented that suggests an association between equilibrium levels of rectal temperature and the osmotic concentration of the blood with essentially no influence of variations in plasma volume.

Greenleaf, J. E.↗
NASA NTRS1975

+Gz tolerance in man after 14-day bedrest periods with isometric and isotonic exercise conditioning

The effects of isometric and isotonic exercise training on post-bedrest +Gz tolerance were determined. In general, 14-day bedrest resulted in a significant loss of Gz tolerance, as previously discovered. At 2.1 Gz, neither the isometric nor the isotonic exercises regimens resulted in a significant increase in post-bedrest Gz tolerance. However, following isometric exercise, restoration of about half the tolerance decrement occurred at 3.2 Gz and 3.8 Gz. Possible reasons for this partial restoration of tolerance are put forward.

Greenleaf, J. E.↗