Exercise, Sleep Quality and Nocturnal Fat Oxidation in Metabolic Syndrome: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Exercise, Sleep Quality and Nocturnal Fat Oxidation in Metabolic Syndrome (NCT04105218), a randomized na study. The primary outcome is Nocturnal FFA Concentrations.

2. Clinical Question

The study’s broader purpose was to examine whether the time of day exercise is performed influences sleep quality and overnight fat metabolism. Its stated measurements also included nocturnal fat oxidation, glucose and insulin concentrations, sleep quality, sleep latency and sleep interruptions. The record does not report comparative results for these outcomes.

For the primary question, the record therefore establishes the intended comparison and measurement, but not an estimated effect. It does not show whether FFA concentrations differed between conditions, the direction or size of any difference, or how precisely such a difference could have been estimated.

3. Trial Design

The registry describes a randomized crossover study with no masking. In a crossover design, participants receive or undergo each study condition, and comparisons can be made within the same participant. This structure can account for some stable differences between participants, but interpretation depends on how condition order and possible effects carried over from an earlier condition are handled.

The planned conditions were evening exercise and control. The brief summary says each visit would last 30 hours and require a stay in a metabolic room. During the exercise condition, participants were to exercise in the early evening; during the control condition, no exercise was performed. The arm description specifies 45-minutes of moderate-intensity continuous treadmill exercise. The available description of that arm is incomplete after the phrase “12 hours after,” so the remaining timing detail is not reported in the registry record.

The record lists enrollment as 12 and the study status as terminated. Enrollment does not establish how many participants completed both conditions or contributed data to any outcome. The record gives a study start date of 2019-08-15 and a primary completion date of 2021-03-02. It lists the phase as NA. The reason for termination is not reported in the registry record.

The record does not describe the randomized sequence, the interval between conditions, or any procedures for assessing or addressing carryover. It also does not report the planned statistical model or a sample-size justification. These omissions matter because they limit assessment of how a within-participant comparison would have been analyzed and how much information the study was intended to collect.

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

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Study terminated before sufficient outcome measure data could be collected to make analysis possible for this outcome measure. No data was able to be analyzed.

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.

6. Primary Endpoint

The registry lists the primary outcome as Nocturnal FFA Concentrations, measured over 8-hours.

The primary endpoint is nocturnal free fatty acid (FFA) concentrations, with an 8-hours timeframe. FFA are circulating fatty acids; in general, measuring their concentrations can characterize an aspect of lipid metabolism. The study’s stated aim was to investigate overnight fat metabolism in relation to evening exercise, making nocturnal FFA concentrations relevant to its research question.

Concentration is a measured quantity, but the registry does not specify a unit, summary statistic, or analysis method for this endpoint. It does not say whether the intended comparison was based on a mean, a change, or another summary. Those details are not reported in the registry record.

Most importantly, the registry states that the study terminated before sufficient outcome data could be collected to make analysis possible, and that no data were able to be analyzed for this outcome. There is consequently no reported estimate comparing the exercise and control conditions, no measure of uncertainty around such an estimate, and no reported test of the primary question. The endpoint describes what the investigators intended to measure; it does not constitute a result.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a crossover design compare?

In general, a crossover study compares conditions experienced by the same participants. A within-participant comparison can reduce the influence of characteristics that remain relatively stable over the study, because each participant serves as their own comparator. That advantage depends on complete and appropriately timed condition data, as well as an analysis that respects the pairing.

For this study, the intended conditions were evening exercise and control, and the registry identifies the model as crossover. The record does not say how participants were assigned to condition sequences, whether the order was balanced, or how much time separated conditions. It does not report whether carryover was assessed or how period effects were handled. These details matter in a crossover study because responses in a later condition could be influenced by the timing or experience of an earlier one.

What does randomization contribute?

Randomization is a method for assigning study conditions by chance rather than by participant or investigator choice. In general, it can reduce systematic differences associated with assignment, especially when allocation procedures are implemented as planned. The registry lists allocation as randomized, but does not describe the sequence-generation method or concealment procedures. The record also states that masking was none. That identifies the study as unmasked; it does not establish whether outcome measurement or analysis could have been conducted without knowledge of condition.

How would an effect estimate be interpreted?

For a crossover comparison, an analysis would generally need to account for the fact that observations from the same participant are related. A simple independent-groups analysis would not automatically reflect that pairing. The appropriate model and summary depend on the outcome’s distribution, timing and planned estimand. In general, a point estimate describes the observed contrast, while a confidence interval conveys its precision under the analysis assumptions. A p-value addresses compatibility with a specified null hypothesis under those assumptions; it does not describe the size or practical importance of an effect.

The registry does not report an analysis model, a point estimate, a confidence interval or a p-value for the primary outcome. It explicitly says that insufficient outcome data were collected to make analysis possible. Therefore, statistical explanations of estimates and tests are general guidance, not descriptions of analyses performed in this study.

What do the planning assumptions mean?

The planning note describes sample-size illustrations based on a stated fraction of an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms and a normal approximation. Such illustrations are planning calculations, not observed results or evidence of achieved power. They do not establish the study’s original design assumptions or statistical plan. The record does not report a trial-specific sample-size justification, and no numerical planning results are stated in the information available for this analysis.

In general, a planning calculation estimates how much information might be needed to detect an effect under specified assumptions. Its output depends on the assumed effect and variability, the statistical test and the target power. If the assumed effect is drawn from an observed estimate, uncertainty in that estimate also matters. A planning illustration cannot replace a prespecified justification, and it cannot recover an outcome estimate when the trial has no analyzable primary-outcome data.

Why does the absence of an analysis matter?

Statistical inference requires data relevant to the question, a defined comparison and an analysis suited to the design. The record supplies the intended primary measure and comparison but reports that data were insufficient for analysis. Consequently, readers cannot assess the magnitude, direction or precision of the primary contrast from the posted results. Nor can a planned measurement or a count of outcome measures substitute for an estimate.

The registry does not report whether any interim analyses were planned or performed, how missing data were to be handled, or which analysis population would have been used. Those details should not be inferred from the crossover model or from the general planning assumptions. Without them, even a hypothetical analysis plan cannot be reconstructed from the record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists nine outcome measures and names several secondary outcomes: nocturnal fat oxidation; nocturnal glucose and insulin concentrations; sleep quality, expressed as percent time in slow wave sleep; sleep latency; and sleep interruptions. It identifies nocturnal FFA concentrations as the primary outcome. The record reports 0 analyses, and the primary-outcome description says no data could be analyzed because the study terminated before sufficient data were collected.

When a study evaluates multiple outcomes, the chance of obtaining at least one apparently unusual result can increase if many statistical tests are performed. In general, multiplicity procedures can address that issue, but their choice depends on the research questions and analysis plan. The registry record does not report a multiplicity strategy, a hierarchy among secondary outcomes, or which comparisons would have been treated as confirmatory.

The record also does not report a missing-data plan, an analysis population, or the number of participants with usable observations for each measure. Insufficient data for the primary outcome is stated, but the reason and pattern of unavailable data are not. Missingness can affect both precision and interpretation; without information on its extent and causes, its impact cannot be evaluated. The reason for termination is not reported in the registry record.

Because the record reports no analyses, there are no posted outcome tests to adjust or interpret. The lack of a reported multiplicity method does not itself show that a particular analysis was mishandled; it means the planned approach cannot be assessed from the registry record.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

The registry lists the Evening Exercise group with 6 at risk for serious adverse events and 0 serious events, 6 at risk for other adverse events and 0 other events, and 0 deaths. It lists the Control group with the same entries: 6 at risk for serious adverse events and 0 serious events, 6 at risk for other adverse events and 0 other events, and 0 deaths.

These are the reported counts for the registry’s adverse-event categories. Zero recorded events in these entries should not be read as proof that no adverse experiences occurred in any circumstance. The observation period, definitions used for event collection and completeness of reporting are not described in the registry information. The record also does not explain how the risk counts relate to completion of both crossover conditions.

Adverse-event counts address safety reporting, not whether the exercise condition changed nocturnal FFA concentrations or any sleep measure. They do not provide an estimate of the primary metabolic effect, and the registry’s zero event counts cannot fill the absence of primary-outcome analysis.

12. What the Result Does, and Does Not, Mean

The record describes a randomized, unmasked crossover study intended to compare an evening exercise condition with a no-exercise control condition in adults with metabolic syndrome. Its primary measure was nocturnal FFA concentrations over 8-hours. The registry reports that the study was terminated before sufficient data were collected to analyze that outcome.

What the posted results establish is limited to the study’s recorded status, design description, intended measurements and adverse-event entries. The record lists enrollment as 12 and reports 0 analyses. It provides no primary-outcome estimate, interval or test, and no reported comparative results for the listed secondary outcomes. It does not state why the study was terminated.

In general, a lack of an analyzable result is different from a precise estimate showing little or no difference. Without an estimate and its uncertainty, the record cannot establish the size or direction of a condition contrast, or how compatible the data would be with different possible effects. It therefore cannot answer whether evening exercise altered nocturnal FFA concentrations in this study.

Nor should the trial’s intended questions be confused with conclusions. Its stated interest in sleep quality and overnight fat metabolism explains the choice of measurements, but it does not show that those measures changed. The adverse-event entries report zero events in the listed categories for both groups; they do not establish the absence of all possible adverse experiences or provide evidence about metabolic or sleep outcomes.

The appropriate interpretation is that the registry documents a study designed to investigate these questions but does not report analyzable outcome results to resolve them. No treatment recommendation or claim about efficacy follows from this record.

13. Why This Trial Matters Statistically

This study is statistically notable because its design and research question are recorded, while its primary outcome could not be analyzed. That distinction is useful when reading clinical trial registries: a clearly stated endpoint is not equivalent to an estimate, and a completed-looking design description does not guarantee that data support inference.

The crossover model also highlights how design and analysis are linked. In general, comparisons within participants can be informative, but they require methods that account for paired observations and for possible effects of condition order or carryover. The registry identifies the design but does not report sequence, washout, or model details. Those omissions limit evaluation of how a comparative result would have been interpreted even if data had been available.

The study’s aim joined overnight metabolism with sleep measures, making the distinction between primary and secondary outcomes consequential. The record names nocturnal FFA concentrations as primary and lists several sleep and metabolic secondary measures, yet reports 0 analyses. This prevents assessment of both the primary comparison and any patterns across the related outcomes. No multiplicity strategy is reported.

Finally, the record’s status is terminated, but the reason is not reported. Avoiding assumptions about that reason is important: the outcome cannot be attributed to recruitment, safety, feasibility, or a particular statistical issue based on this record. Statistically, the central point is that the registry documents the intended investigation but does not provide results capable of answering its primary question.

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 limitation is the absence of analyzable primary-outcome data. The registry says the study terminated before enough nocturnal FFA data had been collected and that no data could be analyzed for that outcome. It reports 0 analyses, so there is no estimate or measure of precision for the primary comparison.

The registry does not report the reason for termination, the number of participants who completed both conditions, or how many contributed usable measurements to each outcome. Although enrollment is listed as 12, that figure does not establish completion or outcome-specific availability. The record also does not describe condition order, the interval between conditions, carryover assessment, or the planned statistical model.

Outcome reporting is limited. The registry names secondary outcomes but does not report comparative results for them in the information available. It does not specify a missing-data method, analysis population, multiplicity strategy, or whether interim analyses were planned. These gaps prevent evaluation of how missingness, multiple outcomes, or the crossover structure would have been handled.

The adverse-event entries are limited to recorded counts by group. The observation period, event definitions and completeness of collection are not described. These entries should therefore be interpreted as registry-reported counts, rather than a comprehensive account of every possible event.

Finally, the intervention description is incomplete after the phrase “12 hours after,” and the primary endpoint’s unit and summary method are not specified. These omissions constrain reconstruction of the intended measurement and analysis beyond the information explicitly recorded.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Exercise, Sleep Quality and Nocturnal Fat Oxidation in Metabolic Syndrome — NCT04105218.
• Registry record last updated 2021-08-06; status last verified 2021-07.
• Results first posted 2021-08-06.
• 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.

18. Record Summary

The registry describes NCT04105218, “Exercise, Sleep Quality and Nocturnal Fat Oxidation in Metabolic Syndrome,” as a randomized, unmasked crossover study sponsored by University of Colorado, Denver. It lists enrollment as 12, status as terminated, a start date of 2019-08-15 and a primary completion date of 2021-03-02.

The intended conditions were evening exercise and control, with adults with metabolic syndrome as the study population. The primary outcome was nocturnal FFA concentrations over 8-hours. The record states that termination occurred before sufficient data were collected to analyze that outcome, and reports 0 analyses.

The registry lists zero serious adverse events, zero other adverse events and zero deaths for both groups. It does not report the reason for termination, comparative outcome estimates, or the statistical plan for analyzing the intended crossover comparison.