This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for High-Intensity Interval Training to Improve Symptoms of Deployment-Related Respiratory Disease (NCT05849168), a na na study. The primary outcome is Maximum Oxygen Consumption (VO2max).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT05849168 |
| Phase | NA |
| Condition | Occupational Exposure |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 12 |
| Arms in the primary outcome | n/a |
| Lead sponsor | University of Colorado, Denver |
| Results posted | Yes |
2. Clinical Question
Population
Veterans with new respiratory symptoms after deployment to Southwest Asia. The registry summary places these symptoms in the context of exposure to burn pit emissions, desert dust, and other airborne hazards.
Intervention
A 12-week exercise program combining supervised high-intensity interval training on an upright stationary bicycle with home aerobic exercise. The supervised sessions are described as 3x/week and approximately 40 minutes each; home exercise is described as 3x/week for 45 minutes each.
Comparator
No separate comparison group is described. The registry lists a single-group model and allocation as NA, so this is not a randomized comparison of exercise with a control intervention.
Primary question
The primary outcome is maximum oxygen consumption (VO2max), measured during maximal cardiopulmonary exercise testing. The study also asks whether heart or lung abnormalities may contribute to difficulty exercising and whether HIIT is associated with changes in fitness and symptoms. The registry record does not report results that answer these questions.
The study is framed around respiratory symptoms that arise after deployment and the possibility that cardiopulmonary findings may relate to exercise difficulty. Its listed activities include exercise testing, echocardiography, blood tests, and questionnaires before and after the exercise program. The primary endpoint focuses on exercise capacity, while the listed secondary outcomes include echocardiographic measures, a metabolomics measure, and participant-reported feasibility.
Because the design is single-group, any before-and-after observations would describe changes over time among participants in the study, not a randomized contrast with people who did not receive the program. The registry record does not report numerical outcome results, an estimated change in VO2max, or an analysis comparing assessment times. It therefore does not establish whether the exercise program was associated with improvement in fitness or symptoms.
3. Trial Design
This completed pilot study is registered as a single-group, behavioral-intervention study sponsored by the University of Colorado, Denver. The registry lists phase as NA, allocation as NA, and masking as NONE. Enrollment is reported as 12. These design details describe a small exploratory study rather than a randomized comparison between treatment arms.
The population is described as veterans with respiratory symptoms after deployment. The registry summary identifies burn pit emissions, desert dust, and other airborne hazards as exposures relevant to the study context. It describes an initial set of study visits with exercise testing, echocardiography, blood tests, and questionnaires; an exercise program; and a later set of visits with the same broad assessment types.
The exercise program is described as 12 weeks of supervised HIIT on an upright stationary bicycle, with sessions 3x/week and approximately 40 minutes each, together with home aerobic exercise 3x/week for 45 minutes each. The listed intervention is named Exercise training and classified as behavioral. The record does not describe a separate untreated, usual-care, or active-comparator group.
The primary outcome is maximum oxygen consumption (VO2max), obtained using a metabolic cart during maximal cardiopulmonary exercise testing and expressed in ml/kg/min. The registry specifies a median and inter-quartile range as the outcome parameter and dispersion, with a timeframe of up to 1 hour. Secondary outcomes include left ventricular ejection fraction and tricuspid annular plane systolic excursion measured by transthoracic echocardiogram, plasma acylcarnitine 10:0 measured by metabolomics, and feasibility reported by participants through questionnaire responses.
The registry lists the study as completed, with a start date of 2023-11-27 and primary completion date of 2024-07-31. It does not report an analysis plan, a sample-size justification, or numerical outcome results. Completion status alone does not indicate what the study found.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Overall Study
| Stage | Veterans With Respiratory Symptoms |
|---|---|
| STARTED | 12 |
| COMPLETED | 11 |
| NOT COMPLETED | 1 |
5. Baseline Characteristics
The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.
| Characteristic | Unit | Veterans With Respiratory Symptoms |
|---|---|---|
| Participants analysed | 12 | |
| Age, Continuous | Years | 46 (SD 11) |
| Sex: Female, Male: Female | Participants | 0 |
| Sex: Female, Male: Male | Participants | 12 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 1 |
| Race (NIH/OMB): Asian | Participants | 1 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race (NIH/OMB): Black or African American | Participants | 2 |
| Race (NIH/OMB): White | Participants | 7 |
| Race (NIH/OMB): More than one race | Participants | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 1 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 1 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 11 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 |
6. Primary Endpoint
The registry lists the primary outcome as Maximum Oxygen Consumption (VO2max), measured over Up to 1 hour.
| Element | Registry entry |
|---|---|
| Result type | Median |
| Measure of spread | Inter-Quartile Range |
| Unit | ml/kg/min |
| Endpoint classification | not reduced to a single comparison |
Maximum oxygen consumption (VO2max) is the primary endpoint. It represents the maximum rate at which oxygen is consumed during exertion and is used as a measure of exercise capacity. In this study, VO2max is obtained using a metabolic cart during maximal cardiopulmonary exercise testing and reported in ml/kg/min. The registry specifies that the outcome is summarized by its median and inter-quartile range.
As a general statistical point, an exercise-capacity measure can help describe physiological performance during a standardized test. It does not by itself identify the cause of respiratory symptoms or establish that an exercise program caused a change. In a single-group study, changes across assessments may coincide with the intervention but can also reflect factors not separated by a control-group comparison.
The registry summary describes exercise testing at the initial and later study visits, around the exercise program. However, the primary outcome timeframe is recorded as up to 1 hour, and the registry record does not report numerical VO2max values, a change estimate, or an inferential analysis. Thus, the endpoint is specified, but the posted record does not show whether it changed or how precisely any change was estimated.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies a completed pilot study with enrollment of 12 and a single-group design. It describes a 12-week exercise program and names VO2max as the primary outcome. It does not report numerical results for VO2max or the other outcomes, and it lists no analyses. The available record therefore supports a description of the study design, not a conclusion about the direction or size of any outcome change.
The study summary describes assessments before and after the exercise program. If measurements were made at both times, a within-participant comparison could describe how values differed over time. But without a separate comparison group, such a change would not isolate the effect of the exercise program from other explanations, such as natural variation, changes in circumstances, or effects of repeated testing. These are general interpretive considerations, not findings reported for this study.
The primary outcome is specified as a median with an inter-quartile range. A median describes the middle of the observed values, while the inter-quartile range describes the spread of the central portion of those values. These summaries can be useful when a distribution is skewed or when extreme observations may make a mean less representative. They do not, by themselves, show whether a change is statistically distinguishable from chance or whether it is clinically important.
No effect estimate, confidence interval, p-value, or analysis population is reported in the registry record. Consequently, the precision of an estimated change cannot be assessed, and neither statistical significance nor the range of plausible effects can be judged from the posted results. A confidence interval, in general, expresses uncertainty around an estimate; it is not a guarantee that the true effect lies within a particular interval.
The registry describes secondary outcomes involving echocardiographic measures, a metabolomics measure, and participant-reported feasibility. It also reports 6 outcome measures, but the record does not provide numerical results for them. Without results for the primary and secondary outcomes, the record cannot establish whether participants' exercise capacity, cardiac measures, metabolomics measures, or reported feasibility changed.
The enrollment and pilot designation are relevant when considering what a study can estimate, but they do not substitute for results or quantify precision. No sample-size justification is reported in the registry record. Any planning illustrations based on an observed effect should be read as assumptions for future planning, not as observed power or evidence that the intervention produced an effect. The registered single-group design also differs from the equal-allocation, two-arm assumptions described for those planning illustrations.
9. Statistical Methods Explained
The registry identifies a single-group study, with allocation recorded as NA and masking as NONE. In general, a single-group design observes participants receiving an intervention without a concurrent randomized control group. If outcomes are measured before and after the intervention, the comparison describes change within the enrolled group. It cannot, on its own, distinguish intervention effects from other events or changes occurring over the same period. That limitation matters when interpreting any apparent improvement or worsening.
What does the primary outcome summary describe?
The primary endpoint is maximum oxygen consumption (VO2max), measured in ml/kg/min during maximal cardiopulmonary exercise testing using a metabolic cart. The registry specifies a median and inter-quartile range. The median is a measure of central location based on the ordered observations. The inter-quartile range describes the span of the middle half of the observations. In general, these summaries are less influenced by extreme values than the mean and standard deviation, though they do not show every feature of a distribution.
A median and inter-quartile range describe observed values; they do not provide an estimate of the uncertainty in a before-and-after difference. To assess a change, an analysis would need to define how repeated measurements are compared and report an estimate with an appropriate measure of uncertainty. The registry record does not report such an analysis or its results.
How should a confidence interval be understood?
In general, a confidence interval is an uncertainty interval around an estimated quantity, such as a difference between assessment times. A narrow interval indicates greater precision than a wide interval, given the model and data used. It does not by itself show that an effect is important, and it does not remove limitations caused by the study design. No confidence interval for VO2max or other outcomes is reported in the registry record.
Why can over-dispersion matter?
As a general concept, over-dispersion occurs when observed variability is greater than a statistical model expects. It can make standard errors too small if the model does not accommodate the extra variability, creating misleadingly precise estimates or tests. Modeling choices should match the outcome type and distribution. The registry record does not report a statistical model, an assessment of over-dispersion, or an analysis plan, so no study-specific conclusion about those choices is possible.
What do the planning assumptions mean?
The record describes planning illustrations based on an observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The effect to detect is described as a stated fraction of the observed effect. For time-to-event planning, the stated quantity is total events; for other planning illustrations, it is participants per arm. Such calculations are planning illustrations, not observed power and not results from the trial.
Those assumptions require particular care in this case. The registered study is single-group, not a randomized, equal-allocation, two-arm trial. Therefore, a two-arm planning calculation does not describe the actual design. Also, the registry record does not report the observed effect used for the illustration or the numerical planning estimates. A future study would need assumptions appropriate to its intended design and target effect; this is a general planning principle, not a protocol reported for this trial.
What cannot be inferred from the registered design?
Masking is listed as NONE, but the record does not explain which study roles were unmasked or how outcome assessments were conducted. A maximal exercise test has a defined measurement procedure, yet the registry description alone does not establish how reproducible the measurements were or whether assessors were blinded. The record also does not report details of adherence, protocol deviations, or the handling of incomplete observations. These omissions prevent a fuller appraisal of the analysis and measurement process.
Most importantly, the registry record lists zero analyses and does not post numerical outcome results. Statistical summaries or calculations cannot be reconstructed from the design description alone. Without estimates and uncertainty measures, readers cannot evaluate the size, direction, or precision of any observed change. General statistical explanations help clarify what a result would mean, but they cannot replace results that are not reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry record reports 6 outcome measures and names the primary endpoint, maximum oxygen consumption (VO2max), along with secondary outcomes involving echocardiographic measurements, plasma acylcarnitine 10:0, and participant-reported feasibility. It does not report an analysis plan describing how the primary and secondary outcomes were prioritized in testing, or how multiple statistical comparisons were handled. When many outcomes are tested, the chance of at least one apparently notable result can increase; adjustment or a prespecified hierarchy can address this in some settings. No such approach is reported.
The registry lists zero analyses and provides no outcome estimates, p-values, confidence intervals, or detailed analysis populations. It does not report how missing measurements were handled, whether participants with incomplete assessments were excluded, or whether any imputation method was used. These details are important because missing outcomes can affect both the estimated change and its precision, particularly if missingness is related to participant experience or outcome values.
The enrollment figure is 12, but the registry does not report the number with available data for each outcome or assessment time. The adverse-event figures separately report 12 at risk for serious and other events; those figures should not be treated as evidence that all participants contributed outcome data. No reason for missing data, if any, is reported. Accordingly, the completeness of the outcome dataset and the robustness of any analysis cannot be assessed from the registry record.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Veterans With Respiratory Symptoms | 0 | 12 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Veterans With Respiratory Symptoms | 0 of 12 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Veterans With Respiratory Symptoms | 0 of 12 |
The registry's adverse-event record lists 12 participants at risk for serious events and 0 affected, and 12 at risk for other events and 0 affected. It also records 0 deaths and no top serious-event terms. These are the posted safety figures; they are not a comparison of event rates between study groups, because the study is registered as single-group.
A zero in an adverse-event field means that the registry record reports no affected participants for that category. It should not be read as proof that the exercise program has no risks or that no event occurred outside the registry's reporting scope. The record does not report the safety monitoring period, detailed event definitions, or further information about ascertainment and reporting. Without those details, the completeness and scope of the safety information cannot be fully assessed.
These figures also do not establish that the intervention caused or prevented an event. There is no separate comparator group in the design, and the registry record does not describe a causal safety analysis. The reported counts are best interpreted as a limited description of events recorded for this study, not as a general estimate of safety.
12. What the Result Does, and Does Not, Mean
The record establishes that a completed pilot study examined an exercise program for veterans with respiratory symptoms after deployment. It specifies a single-group design, enrollment of 12, a 12-week exercise program, and maximum oxygen consumption as the primary endpoint. It also lists other measures related to cardiac function, metabolomics, and feasibility. These details describe the study's aims and structure, not its findings.
The registry record does not report numerical outcome results or analyses. It is therefore not possible to determine from the posted results whether VO2max changed, whether symptoms changed, or how precise any estimated change might be. The same limitation applies to the listed secondary outcomes. Completion status indicates that the study is recorded as completed; it does not supply evidence about its outcomes.
Even if changes across the initial and later visits were reported, a single-group before-and-after comparison would not by itself show that the exercise program caused those changes. Without a concurrent control group, other factors over time cannot be separated from the intervention. This is a general limitation of the design, not a claim that any particular alternative explanation occurred in this study.
The pilot setting can be useful for describing feasibility and informing later research, but the registry does not report a sample-size justification or results that permit evaluation of feasibility. The planning assumptions described in the record are not a substitute for observed outcomes and are not observed power. The posted information supports a careful account of the research question and methods, while leaving the magnitude, direction, and uncertainty of any outcome effects unresolved.
13. Why This Trial Matters Statistically
This study raises a statistical question that is important for early-stage clinical research: how should changes in a physiological measure be interpreted when participants receive an intervention without a randomized control group? The registry's focus on VO2max gives the study a defined primary measure of exercise capacity, while the additional outcomes address cardiac measures, metabolomics, and participant-reported feasibility.
The distinction between a measured change and an intervention effect is central. In a single-group study, repeated measurements can describe trajectories among participants, but they do not provide the counterfactual comparison needed to isolate what would have happened without the intervention. This matters for interpreting both promising changes and apparent lack of change. General statistical methods can quantify uncertainty around a measured difference, but they cannot by themselves remove confounding from an uncontrolled design.
The pilot designation also draws attention to the role of feasibility and measurement quality in planning later research. The registry lists feasibility as an outcome, but does not report its results. It also includes planning assumptions based on an observed effect, with equal allocation between two arms, even though the registered study is single-group. That difference illustrates why a planning method must align with the eventual design and outcome analysis.
At present, the posted record allows readers to identify the intended question and assess broad design features, but it does not allow them to evaluate findings. Outcome estimates, uncertainty intervals, and analysis details would be needed to judge how much information the study produced and what questions a future trial should address.
14. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
The main trial-specific limitation for interpreting results is that the registry record does not post numerical outcomes or analyses. There is no reported VO2max estimate, change over time, confidence interval, or p-value. The record therefore does not support an assessment of effect magnitude or precision.
The design is single-group, with no separate randomized comparator. Any before-and-after difference, if reported elsewhere, would not by itself distinguish an intervention-associated change from changes over time or other influences. The registry lists masking as NONE, but does not specify which roles were unmasked or detail outcome-assessment procedures.
The record describes enrollment of 12 and labels the study a pilot. It does not report a sample-size justification, the number of participants with available data for each outcome, adherence to the exercise program, or how missing measurements and protocol deviations were handled. It also does not report an analysis plan or a method for addressing multiple outcomes.
The exercise program is described in broad terms, but the registry record does not report participant-level exposure, completion, or fidelity information. The safety figures show no affected participants in the recorded categories, but further details about the observation period and event ascertainment are not reported. These limitations leave important questions about outcome completeness, measurement, and interpretation unanswered.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: High-Intensity Interval Training to Improve Symptoms of Deployment-Related Respiratory Disease — NCT05849168.
- Registry record last updated 2026-01-29; status last verified 2026-01.
- Results first posted 2026-01-29.
- Data retrieved from ClinicalTrials.gov on 2026-11-09.
- Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.
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18. Record Summary
The registry describes a completed, single-group pilot study sponsored by the University of Colorado, Denver, with enrollment of 12. It lists veterans with respiratory symptoms after deployment as the population and a 12-week exercise program combining supervised HIIT and home aerobic exercise as the intervention. The primary outcome is maximum oxygen consumption (VO2max), measured during maximal cardiopulmonary exercise testing.
The record lists secondary outcomes related to echocardiographic measures, plasma acylcarnitine 10:0, and participant-reported exercise-program feasibility. It reports 6 outcome measures and zero analyses. Numerical outcome results and details of missing-data handling, multiplicity, and the analysis plan are not reported in the registry record.
The posted safety figures report 0 affected participants for serious events, 0 for other events, and 0 deaths. The study is recorded as completed, but its results and their precision cannot be evaluated from the information reported.