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Wang L, Li Z, Tan C, Liu S, Zhang J, He S, Zou P, Liu W, Li Y. Physiological effects of weightlessness: countermeasure system development for a long-term Chinese manned spaceflight. Front Med 2018; 13:202-212. [PMID: 29693211 DOI: 10.1007/s11684-017-0587-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Accepted: 08/24/2017] [Indexed: 12/15/2022]
Abstract
The Chinese space station will be built around 2020. As a national space laboratory, it will offer unique opportunities for studying the physiological effects of weightlessness and the efficacy of the countermeasures against such effects. In this paper, we described the development of countermeasure systems in the Chinese space program. To emphasize the need of the Chinese space program to implement its own program for developing countermeasures, we reviewed the literature on the negative physiological effects of weightlessness, the challenges of completing missions, the development of countermeasure devices, the establishment of countermeasure programs, and the efficacy of the countermeasure techniques in American and Russian manned spaceflights. In addition, a brief overview was provided on the Chinese research and development on countermeasures to discuss the current status and goals of the development of countermeasures against physiological problems associated with weightlessness.
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Affiliation(s)
- Linjie Wang
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, 100094, China.
| | - Zhili Li
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, 100094, China
| | - Cheng Tan
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, 100094, China
| | - Shujuan Liu
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, 100094, China
| | - Jianfeng Zhang
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, 100094, China
| | - Siyang He
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, 100094, China
| | - Peng Zou
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, 100094, China
| | - Weibo Liu
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, 100094, China
| | - Yinghui Li
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, 100094, China
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Schneider SM, Lee SMC, Feiveson AH, Watenpaugh DE, Macias BR, Hargens AR. Treadmill exercise within lower body negative pressure protects leg lean tissue mass and extensor strength and endurance during bed rest. Physiol Rep 2017; 4:4/15/e12892. [PMID: 27495299 PMCID: PMC4985554 DOI: 10.14814/phy2.12892] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2016] [Accepted: 07/19/2016] [Indexed: 01/26/2023] Open
Abstract
Leg muscle mass and strength are decreased during reduced activity and non‐weight‐bearing conditions such as bed rest (BR) and spaceflight. Supine treadmill exercise within lower body negative pressure (LBNPEX) provides full‐body weight loading during BR and may prevent muscle deconditioning. We hypothesized that a 40‐min interval exercise protocol performed against LBNPEX 6 days week−1 would attenuate losses in leg lean mass (LLM), strength, and endurance during 6° head‐down tilt BR, with similar benefits for men and women. Fifteen pairs of healthy monozygous twins (8 male and 7 female pairs) completed 30 days of BR with one sibling of each twin pair assigned randomly as the non‐exercise control (CON) and the other twin as the exercise subject (EX). Before and after BR, LLM and isokinetic leg strength and endurance were measured. Mean knee and ankle extensor and flexor strength and endurance and LLM decreased from pre‐ to post‐BR in the male CON subjects (P < 0.01), but knee extensor strength and endurance, ankle extensor strength, and LLM were maintained in the male EX subjects. In contrast, no pre‐ to post‐BR changes were significant in the female subjects, either CON or EX, likely due to their lower pre‐BR values. Importantly, the LBNPEX countermeasure prevents or attenuates declines in LLM as well as extensor leg strength and endurance. Individuals who are stronger, have higher levels of muscular endurance, and/or have greater LLM are likely to experience greater losses during BR than those who are less fit.
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Affiliation(s)
| | - Stuart M C Lee
- Wyle Science, Technology, and Engineering Group, Houston, Texas
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Hargens AR, Vico L. Long-duration bed rest as an analog to microgravity. J Appl Physiol (1985) 2016; 120:891-903. [PMID: 26893033 DOI: 10.1152/japplphysiol.00935.2015] [Citation(s) in RCA: 172] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Accepted: 02/12/2016] [Indexed: 11/22/2022] Open
Abstract
Long-duration bed rest is widely employed to simulate the effects of microgravity on various physiological systems, especially for studies of bone, muscle, and the cardiovascular system. This microgravity analog is also extensively used to develop and test countermeasures to microgravity-altered adaptations to Earth gravity. Initial investigations of bone loss used horizontal bed rest with the view that this model represented the closest approximation to inactivity and minimization of hydrostatic effects, but all Earth-based analogs must contend with the constant force of gravity by adjustment of the G vector. Later concerns about the lack of similarity between headward fluid shifts in space and those with horizontal bed rest encouraged the use of 6 degree head-down tilt (HDT) bed rest as pioneered by Russian investigators. Headward fluid shifts in space may redistribute bone from the legs to the head. At present, HDT bed rest with normal volunteers is the most common analog for microgravity simulation and to test countermeasures for bone loss, muscle and cardiac atrophy, orthostatic intolerance, and reduced muscle strength/exercise capacity. Also, current physiologic countermeasures are focused on long-duration missions such as Mars, so in this review we emphasize HDT bed rest studies with durations of 30 days and longer. However, recent results suggest that the HDT bed rest analog is less representative as an analog for other important physiological problems of long-duration space flight such as fluid shifts, spinal dysfunction and radiation hazards.
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Affiliation(s)
- Alan R Hargens
- Department of Orthopaedic Surgery, University of California, San Diego, San Diego, California; and Institut National de la Santé et de la Recherche Médicale Unité 1059, University of Lyon, St-Etienne, France
| | - Laurence Vico
- Department of Orthopaedic Surgery, University of California, San Diego, San Diego, California; and Institut National de la Santé et de la Recherche Médicale Unité 1059, University of Lyon, St-Etienne, France
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Hackney KJ, English KL. Protein and Essential Amino Acids to Protect Musculoskeletal Health during Spaceflight: Evidence of a Paradox? Life (Basel) 2014; 4:295-317. [PMID: 25370374 PMCID: PMC4206848 DOI: 10.3390/life4030295] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 06/19/2014] [Accepted: 06/23/2014] [Indexed: 11/17/2022] Open
Abstract
Long-duration spaceflight results in muscle atrophy and a loss of bone mineral density. In skeletal muscle tissue, acute exercise and protein (e.g., essential amino acids) stimulate anabolic pathways (e.g., muscle protein synthesis) both independently and synergistically to maintain neutral or positive net muscle protein balance. Protein intake in space is recommended to be 12%-15% of total energy intake (≤1.4 g∙kg-1∙day-1) and spaceflight is associated with reduced energy intake (~20%), which enhances muscle catabolism. Increasing protein intake to 1.5-2.0 g∙kg-1∙day-1 may be beneficial for skeletal muscle tissue and could be accomplished with essential amino acid supplementation. However, increased consumption of sulfur-containing amino acids is associated with increased bone resorption, which creates a dilemma for musculoskeletal countermeasures, whereby optimizing skeletal muscle parameters via essential amino acid supplementation may worsen bone outcomes. To protect both muscle and bone health, future unloading studies should evaluate increased protein intake via non-sulfur containing essential amino acids or leucine in combination with exercise countermeasures and the concomitant influence of reduced energy intake.
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Affiliation(s)
- Kyle J Hackney
- Department of Health, Nutrition, and Exercise Sciences, North Dakota State University, Fargo, ND 58102, USA.
| | - Kirk L English
- Exercise Physiology and Countermeasures Laboratory, JES Tech, Houston, TX 77058, USA.
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Hargens AR, Bhattacharya R, Schneider SM. Space physiology VI: exercise, artificial gravity, and countermeasure development for prolonged space flight. Eur J Appl Physiol 2012; 113:2183-92. [DOI: 10.1007/s00421-012-2523-5] [Citation(s) in RCA: 100] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Accepted: 10/05/2012] [Indexed: 01/06/2023]
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Genc KO, Gopalakrishnan R, Kuklis MM, Maender CC, Rice AJ, Bowersox KD, Cavanagh PR. Foot forces during exercise on the International Space Station. J Biomech 2010; 43:3020-7. [PMID: 20728086 DOI: 10.1016/j.jbiomech.2010.06.028] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2010] [Revised: 06/28/2010] [Accepted: 06/30/2010] [Indexed: 11/29/2022]
Abstract
Long-duration exposure to microgravity has been shown to have detrimental effects on the human musculoskeletal system. To date, exercise countermeasures have been the primary approach to maintain bone and muscle mass and they have not been successful. Up until 2008, the three exercise countermeasure devices available on the International Space Station (ISS) were the treadmill with vibration isolation and stabilization (TVIS), the cycle ergometer with vibration isolation and stabilization (CEVIS), and the interim resistance exercise device (iRED). This article examines the available envelope of mechanical loads to the lower extremity that these exercise devices can generate based on direct in-shoe force measurements performed on the ISS. Four male crewmembers who flew on long-duration ISS missions participated in this study. In-shoe forces were recorded during activities designed to elicit maximum loads from the various exercise devices. Data from typical exercise sessions on Earth and on-orbit were also available for comparison. Maximum on-orbit single-leg loads from TVIS were 1.77 body weight (BW) while running at 8mph. The largest single-leg forces during resistance exercise were 0.72 BW during single-leg heel raises and 0.68 BW during double-leg squats. Forces during CEVIS exercise were small, approaching only 0.19 BW at 210W and 95RPM. We conclude that the three exercise devices studied were not able to elicit loads comparable to exercise on Earth, with the exception of CEVIS at its maximal setting. The decrements were, on average, 77% for walking, 75% for running, and 65% for squats when each device was at its maximum setting. Future developments must include an improved harness to apply higher gravity replacement loads during locomotor exercise and the provision of greater resistance exercise capability. The present data set provides a benchmark that will enable future researchers to judge whether or not the new generation of exercise countermeasures recently added to the ISS will address the need for greater loading.
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Affiliation(s)
- K O Genc
- Department of Orthopaedics and Sports Medicine, University of Washington, BB 1065D, 1959 NE Pacific Street, Box 356500, Seattle, WA 98195-6500, USA
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Hand J, Verscheure S, Osternig L. A comparison of whole-body vibration and resistance training on total work in the rotator cuff. J Athl Train 2010; 44:469-74. [PMID: 19771284 DOI: 10.4085/1062-6050-44.5.469] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
CONTEXT Whole-body vibration machines are a relatively new technology being implemented in the athletic setting. Numerous authors have examined the proposed physiologic mechanisms of vibration therapy and performance outcomes. Changes have mainly been observed in the lower extremity after individual exercises, with minimal attention to the upper extremity and resistance training programs. OBJECTIVE To examine the effects of a novel vibration intervention directed at the upper extremity as a precursor to a supervised, multijoint dynamic resistance training program. DESIGN Randomized controlled trial. SETTING National Collegiate Athletic Association Division IA institution. PATIENTS OR OTHER PARTICIPANTS Thirteen female student-athletes were divided into the following 2 treatment groups: (1) whole-body vibration and resistance training or (2) resistance training only. INTERVENTION(S) Participants in the vibration and resistance training group used an experimental vibration protocol of 2 x 60 seconds at 4 mm and 50 Hz, in a modified push-up position, 3 times per week for 10 weeks, just before their supervised resistance training session. MAIN OUTCOME MEASURE(S) Isokinetic total work measurements of the rotator cuff were collected at baseline and at week 5 and week 10. RESULTS No differences were found between the treatment groups (P > .05). However, rotator cuff output across time increased in both groups (P < .05). CONCLUSIONS Although findings did not differ between the groups, the use of whole-body vibration as a precursor to multijoint exercises warrants further investigation because of the current lack of literature on the topic. Our results indicate that indirectly strengthening the rotator cuff using a multijoint dynamic resistance training program is possible.
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Sibonga JD, Cavanagh PR, Lang TF, LeBlanc AD, Schneider VS, Shackelford LC, Smith SM, Vico L. Adaptation of the Skeletal System During Long-Duration Spaceflight. Clin Rev Bone Miner Metab 2008. [DOI: 10.1007/s12018-008-9012-8] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Kaneko M, Miyatsuji K, Tanabe S. Energy expenditure while performing gymnastic-like motion in spacelab during spaceflight: case study. Appl Physiol Nutr Metab 2006; 31:631-4. [PMID: 17111018 DOI: 10.1139/h06-039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To estimate energy cost of a gymnastic-like exercise performed by an astronaut during spaceflight (cosmic exercise), energy expenditure was determined by measuring mechanical work done around the center of mass (COM) of the body. The cosmic exercise, which consisted of whole-body flexion and extension, was performed during a spaceflight and recorded with a video camera. By analyzing the videotape, the internal mechanical work (W(int)) against inertia load of the body segments was calculated. To compare how human muscles work on Earth, a motion similar to the cosmic exercise was performed by a control subject who had a physique similar to that of the astronaut. The total mechanical power of the astronaut was determined to be about 119 W; although the control subject showed a similar total power value, half of the power was external work (W(ext)) against gravitational load. By assuming a mechanical efficiency of 0.25, the energy expenditure was estimated to be 476 W or 7.7 W/kg, which is equivalent to that expended during fast walking and half of that used during moderate-speed running. Our results suggest that this form of cosmic exercise is appropriate for astronauts in space and can be performed safely, as there are no COM shifts while floating in a spacecraft and no vibratory disturbance.
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Affiliation(s)
- Masahiro Kaneko
- Biomechanics Laboratory, Osaka University of Health and Sport Sciences, Osaka, Japan 590-0496.
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Abstract
As a direct consequence of exposure to microgravity, astronauts experience a set of physiological changes which can have serious medical implications when they return to earth. Most immediate and significant are the headward shift of body fluids and the removal of gravitational loading from bone and muscles, which lead to progressive changes in the cardiovascular and musculoskeletal systems. Cardiovascular adaptations result in an increased incidence of orthostatic intolerance (fainting) following flight, decreased cardiac output, and reduced capacity for exercise. Changes in the musculoskeletal system contribute significantly to impaired function experienced in the post-flight period. The underlying factor producing these changes is the absence of gravity, and countermeasures are therefore designed primarily to simulate earthlike movements, stresses, and system interactions. Exercise is one approach that has had wide operational use and acceptance in both the US and Russian space programmes, and it has enabled humans to stay relatively healthy in space for well over a year. Although it remains the most effective countermeasure currently available, significant physiological degradation still occurs. The development of other countermeasures will be necessary for missions of longer duration, for example for human exploration of Mars.
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Affiliation(s)
- Adam Hawkey
- School of Sport, Exercise and Health Sciences, University College Chichester, UK.
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Peterman MM, Hamel AJ, Cavanagh PR, Piazza SJ, Sharkey NA. In vitro modeling of human tibial strains during exercise in micro-gravity. J Biomech 2001; 34:693-8. [PMID: 11311711 DOI: 10.1016/s0021-9290(01)00004-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Prolonged exposure to micro-gravity causes substantial bone loss (Leblanc et al., Journal of Bone Mineral Research 11 (1996) S323) and treadmill exercise under gravity replacement loads (GRLs) has been advocated as a countermeasure. To date, the magnitudes of GRLs employed for locomotion in space have been substantially less than the loads imposed in the earthbound 1G environment, which may account for the poor performance of locomotion as an intervention. The success of future treadmill interventions will likely require GRLs of greater magnitude. It is widely held that mechanical tissue strain is an important intermediary signal in the transduction pathway linking the external loading environment to bone maintenance and functional adaptation; yet, to our knowledge, no data exist linking alterations in external skeletal loading to alterations in bone strain. In this preliminary study, we used unique cadaver simulations of micro-gravity locomotion to determine relationships between localized tibial bone strains and external loading as a means to better predict the efficacy of future exercise interventions proposed for bone maintenance on orbit. Bone strain magnitudes in the distal tibia were found to be linearly related to ground reaction force magnitude (R(2)>0.7). Strain distributions indicated that the primary mode of tibial loading was in bending, with little variation in the neutral axis over the stance phase of gait. The greatest strains, as well as the greatest strain sensitivity to altered external loading, occurred within the anterior crest and posterior aspect of the tibia, the sites furthest removed from the neutral axis of bending. We established a technique for estimating local strain magnitudes from external loads, and equations for predicting strain during simulated micro-gravity walking are presented.
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Affiliation(s)
- M M Peterman
- Center for Locomotion Studies, 29 Recreation Building, Pennsylvania State University, University Park, PA 16802-5702, USA
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Chang YH, Hamerski CM, Kram R. Applied horizontal force increases impact loading in reduced-gravity running. J Biomech 2001; 34:679-85. [PMID: 11311709 DOI: 10.1016/s0021-9290(00)00196-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The chronic exposure of astronauts to microgravity results in structural degradation of their lower limb bones. Currently, no effective exercise countermeasure exists. On Earth, the impact loading that occurs with regular locomotion is associated with the maintenance of bone's structural integrity, but impact loads are rarely experienced in space. Accurately mimicking Earth-like impact loads in a reduced-gravity environment should help to reduce the degradation of bone caused by weightlessness. We previously showed that running with externally applied horizontal forces (AHF) in the anterior direction qualitatively simulates the high-impact loading associated with downhill running on Earth. We hypothesized that running with AHF at simulated reduced gravity would produce impact loads equal to or greater than values experienced during normal running at Earth gravity. With an AHF of 20% of gravity-specific body weight at all gravity levels, impact force peaks increased 74%, average impact loading rates increased 46%, and maximum impact loading rates increased 89% compared to running without any AHF. In contrast, AHF did not substantially affect active force peaks. Duty factor and stride frequency decreased modestly with AHF at all gravity levels. We found that running with an AHF in simulated reduced gravity produced impact loads equal to or greater than those experienced at Earth gravity. An appropriate AHF could easily augment existing partial gravity treadmill running exercise countermeasures used during spaceflight and help prevent musculoskeletal degradation.
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Affiliation(s)
- Y H Chang
- Locomotion Laboratory, Department of Integrative Biology, University of California, Berkeley, CA 94720-3140, USA.
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