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A systematic review and meta-analysis of pulmonary function in microgravity Cover

A systematic review and meta-analysis of pulmonary function in microgravity

Open Access
|Jul 2026

Figures & Tables

Figure 1.

Schematic diagram of systematic review focus on exploring functional pulmonary system outcome measures in space during parabolic flight, short- and long-duration spaceflight. Diagram shows parabolic flight path to create microgravity and space station in space for short- and long-duration spaceflight studies. Created with BioRender.com

Figure 2.

PRISMA flow diagram demonstrating summary of literature search and screening process.

Figure 3.

Forest plot for respiration frequency in 0G compared to 1G (i.e., a right-ward shift indicated a larger measure in 1G). Effect sizes are reported as Hedge’s g with 95% confidence intervals.

Figure 4.

Forest plot for minute ventilation in 0G compared to 1G (i.e., a right-ward shift indicated a larger measure in 1G). Effect sizes are reported as Hedge’s g with 95% confidence intervals.

Figure 5.

Forest plot for parameters of pulmonary cellular respiration in 0G compared to 1G (i.e., a right-ward shift indicated a larger measure in 1G). Effect sizes are reported as Hedge’s g with 95% confidence intervals.

Figure 6.

Forest plot for parameters of pulmonary flow rates in 0G compared to 1G (i.e., a right-ward shift indicated a larger measure in 1G). Effect sizes are reported as Hedge’s g with 95% confidence intervals.

Figure 7.

Forest plot for breathing time in 0G compared to 1G (i.e., a right-ward shift indicated a larger measure in 1G). Effect sizes are reported as Hedge’s g with 95% confidence intervals.

Figure 8.

Forest plot for pulmonary diffusing capacity in 0G compared to 1G (i.e., a right-ward shift indicated a larger measure in 1G). Effect sizes are reported as Hedge’s g with 95% confidence intervals.

Figure 9.

Forest plot for pulmonary pressure, compliance, and resistance parameters in 0G compared to 1G (i.e., a right-ward shift indicated a larger measure in 1G). Effect sizes are reported as Hedge’s g with 95% confidence intervals.

Figure S1.

Snapshot of Cochrane search strategy

Summary of pulmonary functional outcome measures in microgravity during parabolic flight, short- and long-duration spaceflight_

Outcome measureParabolicShortLong
Respiration frequency
Minute ventilation (V̇E)
Volume of oxygen consumption (V̇O2)
Volume of carbon dioxide production (V̇CO2)
Forced expiratory flow (FEF)
Mean inspiratory flow (MIF)
Peak expiratory flow rate (PEFR)
Breathing time
Pulmonary diffusing capacity
Pulmonary capillary blood volume (VC)
Pulmonary capillary blood flow (Qc)
Pressure
Compliance
Resistance
Resistivity
Respiratory work
Elastic work
Exercise work rate
Exercise economy

Characteristics and pulmonary outcome measures of included studies_

StudyNumber of participants (n)Sex (M/F)Flight type0G exposure durationOutcome measures
Baevsky et al. 200788/0Long179 dRespiration frequency
Bettinelli et al. 2002a64/2Parabolic20 sPressure, compliance
Bettinelli et al. 2002b43/1Parabolic20 sCompliance
Conkin et al. 201788/0Short10 dRespiration frequency
Dellacá et al. 200454/1Parabolic20 sBreathing time, MIF, V̇E, compliance, respiratory work, elastic work
Di Rienzo et al. 200843/1Short16 dRespiration frequency
Dutrieue et al. 200394/5Parabolic22 sBreathing time, FEF
Dutrieue et al. 200574/3Parabolic18 sBreathing time
Edyvean et al. 199155/0Parabolic18 sRespiration frequency, pressure, compliance, resistance
Elliott et al. 199674/3Short9 dPEFR
Elliott et al. 200154/1Short13 dRespiration frequency
Estenne et al. 199255/0Parabolic20 sBreathing time, MIF, respiration frequency
Frerichs et al. 200176/1Parabolic20 sRespiration frequency
Frerichs et al. 200587/1Parabolic20 sRespiration frequency
Guy et al. 199195/4Parabolic24 sFEF, PEFR
Hahn et al. 20132216/6Parabolic21 sRespiration frequency, resistivity
Levine et al. 199664/2Short14 dV̇O2, V̇E, work rate, economy
Limper et al. 2014189/9Parabolic23 sV̇O2
Prisk et al. 199374/3Short9 dPulmonary diffusing capacity
Prisk et al. 199585/3Short23 dRespiration frequency, V̇O2, V̇CO2, MIF, breathing time, pressure, V̇E
Prisk et al. 200054/1Short16 dRespiration frequency, V̇E, pressure
Prisk et al. 2006109/1Long163 dRespiration frequency, V̇O2, V̇CO2, FEF, PEFR, pressure, V̇E
Sá et al. 200954/1Short17 dBreathing time, MIF, V̇E
Stegemann et al. 199744/0Short10 dV̇O2, V̇CO2, V̇E
Trappe et al. 200644/0Short17 dV̇O2, V̇E
Väida et al. 19971010/0Parabolic20 sPulmonary diffusing capacity
Verbanck et al. 199744/0Short10 dPulmonary diffusing capacity
Verheyden et al. 20101111/0Long180 dRespiration frequency

Results of the meta-analysis for changes in pulmonary function outcome measures in microgravity, and between different time categories (i_e_, parabolic, short, long) in microgravity_

ParameterResidual Het.Effect of MicrogravityEffect of Time

SMD (95% CI)p-valuep-value
CO2 production0.30840.5622 (−0.0063, 1.1306)0.05260.1582
O2 consumption<0.0001−0.0927 (−1.1816, 0.9963)0.8676<.0001
Respiratory Frequency0.0001−0.0152 (−0.5364, 0.506)0.95440.3242
Pulmonary Diffusing Capacity0.1383−2.163 (−3.3896, −0.9364)0.00050.5730
Minute Ventilation0.20650.227 (−0.2059, 0.6600)0.30410.1019
Breathing Time0.0258−0.070 (−0.7533, 0.6133)0.84080.5350
Compliance0.3256−0.8549 (−1.5946, −0.1152)0.0235N/A
Pressure0.2820−0.6487 (−0.9539, −0.3435)<.00010.9617
Resistivity0.9086−0.0058 (−0.5602, 0.5486)0.98350.9835
FEF0.8955−0.0222 (−0.4115, 0.3672)0.91120.8860
MIF0.0006−0.5258 (−2.0184, 0.9668)0.48990.4545
PEFR0.8034−0.115 (−0.5273, 0.2972)0.58450.6251

Analysis of risk of bias of included studies using RoBANS_

StudySelection of participantsConfounding variablesIntervention (exposure) measurementBlinding of outcome assessmentIncomplete outcome dataSelective outcome reportingOverall risk of bias
Baevsky et al. 2007LowUnclearLowUnclearLowLowLow
Bettinelli et al. 2002aLowUnclearLowUnclearLowLowLow
Bettinelli et al. 2002bLowLowLowUnclearLowLowLow
Conkin et al. 2017LowLowLowLowLowLowLow
Dellacá et al. 2004LowUnclearLowUnclearLowLowLow
Di Rienzo et al. 2008LowUnclearLowUnclearUnclearLowUnclear
Dutrieue et al. 2003LowLowLowLowLowLowLow
Dutrieue et al. 2005LowLowLowLowLowLowLow
Edyvean et al. 1991LowUnclearLowUnclearLowLowLow
Elliott et al. 1996LowLowLowUnclearUnclearLowLow
Elliott et al. 2001LowLowLowLowLowLowLow
Estenne et al. 1992LowUnclearLowLowLowLowLow
Frerichs et al. 2001LowUnclearLowUnclearLowLowLow
Frerichs et al. 2005LowLowLowUnclearLowLowLow
Guy et al. 1991LowLowLowUnclearLowLowLow
Hahn et al. 2013LowUnclearLowUnclearUnclearLowUnclear
Levine et al. 1996LowUnclearLowLowHighLowUnclear
Limper et al. 2014LowLowLowLowLowLowLow
Prisk et al. 1993LowLowLowLowHighLowLow
Prisk et al. 1995LowLowLowLowLowLowLow
Prisk et al. 2000LowLowLowLowLowLowLow
Prisk et al. 2006LowLowLowUnclearUnclearLowLow
Sá et al. 2009LowLowLowLowLowLowLow
Stegemann et al. 1997LowLowLowLowLowLowLow
Trappe et al. 2006HighUnclearLowUnclearLowLowUnclear
Väida et al. 1997LowLowLowLowLowLowLow
Verbanck et al. 1997LowLowLowLowUnclearLowLow
Verheyden et al. 2010LowUnclearLowLowLowLowLow

Search strategy_

Search numberTermKeywords in search format
1Lungexp Respiratory Dead Space/ or exp Respiratory Function Tests/ or exp Respiratory Mechanics/ or exp Respiratory Rate/ or exp Respiratory System/ or exp Respiratory Physiological Phenomena/ or exp Respiratory Muscles/ or exp lung/ or exp Diagnostic Techniques, Respiratory System/ or exp Pulmonary Ventilation/ or exp Ventilation-Perfusion Ratio/ or exp Pulmonary Gas Exchange/ or exp Respiration/ or exp Pulmonary Diffusing Capacity/ or Lung.ab. Or Pulmonary.ab.
2Spaceexp spaceflight/ or exp gravitation/ or exp Weightlessness/ or exp Astronauts/ or exp Spacecraft/ or exp Extraterrestrial Environment/ or Microgravity.ab.
3Combined Search1 AND 2

j_gsr-2026-0009_tab_006

Section and TopicItem #Checklist itemLocation where item is reported
TITLE
Title1Identify the report as a systematic review.Included
ABSTRACT
Abstract2See the PRISMA 2020 for Abstracts checklist.Seen and followed
INTRODUCTION
Rationale3Describe the rationale for the review in the context of existing knowledge.Included
Objectives4Provide an explicit statement of the objective(s) or question(s) the review addresses.Included
METHODS
Eligibility criteria5Specify the inclusion and exclusion criteria for the review and how studies were grouped for the syntheses.Section 2.2 and 2.3
Information sources6Specify all databases, registers, websites, organisations, reference lists and other sources searched or consulted to identify studies. Specify the date when each source was last searched or consulted.Section 2.1
Search strategy7Present the full search strategies for all databases, registers and websites, including any filters and limits used.Section 2.1 and Supplementary Material
Selection process8Specify the methods used to decide whether a study met the inclusion criteria of the review, including how many reviewers screened each record and each report retrieved, whether they worked independently, and if applicable, details of automation tools used in the process.Section 2.2
Data collection process9Specify the methods used to collect data from reports, including how many reviewers collected data from each report, whether they worked independently, any processes for obtaining or confirming data from study investigators, and if applicable, details of automation tools used in the process.Section 2.2 and 2.3
Data items10aList and define all outcomes for which data were sought. Specify whether all results that were compatible with each outcome domain in each study were sought (e.g. for all measures, time points, analyses), and if not, the methods used to decide which results to collect.Section 2.3 and 2.4
10bList and define all other variables for which data were sought (e.g. participant and intervention characteristics, funding sources). Describe any assumptions made about any missing or unclear information.Section 2.3 and 2.4
Study risk of bias assessment11Specify the methods used to assess risk of bias in the included studies, including details of the tool(s) used, how many reviewers assessed each study and whether they worked independently, and if applicable, details of automation tools used in the process.Section 2.2
Effect measures12Specify for each outcome the effect measure(s) (e.g. risk ratio, mean difference) used in the synthesis or presentation of results.Section 2.3 and 2.4
Synthesis methods13aDescribe the processes used to decide which studies were eligible for each synthesis (e.g. tabulating the study intervention characteristics and comparing against the planned groups for each synthesis (item #5)).Section 2.2 and 2.3
13bDescribe any methods required to prepare the data for presentation or synthesis, such as handling of missing summary statistics, or data conversions.Section 2.4
13cDescribe any methods used to tabulate or visually display results of individual studies and syntheses.Section 2.3
13dDescribe any methods used to synthesize results and provide a rationale for the choice(s). If meta-analysis was performed, describe the model(s), method(s) to identify the presence and extent of statistical heterogeneity, and software package(s) used.Section 2.4
13eDescribe any methods used to explore possible causes of heterogeneity among study results (e.g. subgroup analysis, meta-regression).Section 2.4
13fDescribe any sensitivity analyses conducted to assess robustness of the synthesized results.Section 2.4
Reporting bias assessment14Describe any methods used to assess risk of bias due to missing results in a synthesis (arising from reporting biases).Section 2.2
Certainty assessment15Describe any methods used to assess certainty (or confidence) in the body of evidence for an outcome.Section 2.4
RESULTS
Study selection16aDescribe the results of the search and selection process, from the number of records identified in the search to the number of studies included in the review, ideally using a flow diagram.Section 3.1
16bCite studies that might appear to meet the inclusion criteria, but which were excluded, and explain why they were excluded.Section 3.1
Study characteristics17Cite each included study and present its characteristics.Section 3.1
Risk of bias in studies18Present assessments of risk of bias for each included study.Section 3.2
Results of individual studies19For all outcomes, present, for each study: (a) summary statistics for each group (where appropriate) and (b) an effect estimate and its precision (e.g. confidence/credible interval), ideally using structured tables or plots.Section 3.3
Results of syntheses20aFor each synthesis, briefly summarise the characteristics and risk of bias among contributing studies.Section 3.2
20bPresent results of all statistical syntheses conducted. If meta-analysis was done, present for each the summary estimate and its precision (e.g. confidence/credible interval) and measures of statistical heterogeneity. If comparing groups, describe the direction of the effect.Section 3.3
20cPresent results of all investigations of possible causes of heterogeneity among study results.Section 3.3
20dPresent results of all sensitivity analyses conducted to assess the robustness of the synthesized results.Section 3.3
Reporting biases21Present assessments of risk of bias due to missing results (arising from reporting biases) for each synthesis assessed.Section 3.3
Certainty of evidence22Present assessments of certainty (or confidence) in the body of evidence for each outcome assessed.Section 3.3
DISCUSSION
Discussion23aProvide a general interpretation of the results in the context of other evidence.Section 4.1
23bDiscuss any limitations of the evidence included in the review.Section 4.2
23cDiscuss any limitations of the review processes used.Section 4.2
23dDiscuss implications of the results for practice, policy, and future research.Section 4.3
OTHER INFORMATION
Registration and protocol24aProvide registration information for the review, including register name and registration number, or state that the review was not registered.Review was not registered
24bIndicate where the review protocol can be accessed, or state that a protocol was not prepared.Protocol was not prepared
24cDescribe and explain any amendments to information provided at registration or in the protocol.N/A
Support25Describe sources of financial or non-financial support for the review, and the role of the funders or sponsors in the review.Included in ‘Funding’ section
Competing interests26Declare any competing interests of review authors.Included in ‘Declaration of competing interest’
Availability of data, code and other materials27Report which of the following are publicly available and where they can be found: template data collection forms; data extracted from included studies; data used for all analyses; analytic code; any other materials used in the review.Included in ‘Data statement’
Language: English
Page range: 53 - 75
Published on: Jul 7, 2026
In partnership with: Paradigm Publishing Services
Publication frequency: Volume open

© 2026 Fay Ghani, Irene Cheung, Anthony Phillips, Bruce R. Thompson, Merryn Tawhai, Edward Ashworth, published by American Society for Gravitational and Space Research
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.