The Effects of Altering Physical Activity on Cardiometabolic Health: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for The Effects of Altering Physical Activity on Cardiometabolic Health (NCT01879059), a na na study. The primary outcome is Effects of Physical Inactivity on Post Prandial Blood Flow.

2. Clinical Question

3. Trial Design

The registry record describes a completed, single-group behavioral study sponsored by the University of Kansas Medical Center. Its status is COMPLETED, with enrollment of 13. The record lists phase as NA and allocation as NA. Masking is NONE, and the model is SINGLE GROUP. These entries describe a study without a randomized, masked, parallel control comparison.

The study concerns an acute change in activity among people described as healthy, young, active men for the primary outcome. The summary describes participants as healthy and lean, with activity levels above 10,000 steps/day before the reduction. The recorded intervention is named Exercise, although the arm description specifies 5 days of inactivity followed by a 1 day return to physical activity. The study therefore evaluates a sequence of activity conditions in one group rather than a comparison of separate treatment arms.

The primary outcome description gives an overall timeframe of 10 days. It describes a pre-measurement period of 3 days, then 5 days of inactivity, followed by 1.5-2 days of return to activity. The intervention description instead says a 1 day return. These descriptions differ in how they characterize the return-to-activity period; the record does not clarify the difference. The primary outcome was measured before and after the inactivity period.

The study began in 2012-03, reached primary completion in 2014-10, and is listed as COMPLETED. The record does not report a protocol justification for enrollment, a randomization procedure, or a separate control group. Because the design is single-group, changes across the measured periods cannot be read as a randomized estimate against a concurrent control condition.

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

Analysis population for the primary outcome, as defined in the registry: healthy, young, active men

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.

Population: young, healthy, active men

6. Primary Endpoint

The registry lists the primary outcome as Effects of Physical Inactivity on Post Prandial Blood Flow, measured over 10 days.

The primary endpoint is the percentage of change in blood flow. The record describes blood flow measurement by Doppler ultrasound during an oral glucose tolerance test, before and after 5 days of inactivity. The summary frames the response after a meal as a marker of vascular health and asks whether reducing physical activity alters that response.

In general, an outcome measured as a continuous quantity can describe both the direction and magnitude of change, while a mean can summarize the group’s average value. The record identifies the endpoint parameter as a mean and its dispersion measure as a standard deviation. These are useful descriptions of a continuous outcome: the mean indicates the average, and the standard deviation describes how spread out individual measurements are around that average. Neither statistic, by itself, shows how precisely the mean has been estimated; a confidence interval would address that uncertainty.

The stated timeframe is 10 days, encompassing the pre-measurement period, inactivity, and return to activity. The outcome description specifically identifies measurements before and after inactivity. Although the study summary also asks whether activity can restore the response, the registry record does not report the numerical results for either period, a comparison of those values, or a statistical estimate of restoration. The endpoint is a physiological measurement, not a report of a clinical event or a diagnosis.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record identifies a continuous primary outcome: percentage of change in blood flow. It specifies the mean as the parameter and standard deviation as the measure of dispersion. Those labels describe how a continuous outcome might be summarized; they do not provide the measured mean or standard deviation. Neither quantity is reported for the primary endpoint, and no inferential result is listed.

What does a mean describe?

In general, a mean combines the observed values into an average. For a repeated measurement design, one possible summary is the average within-person change. That summary differs from comparing two unrelated groups, because the measurements from the same person may be related. The registry describes blood flow measurements before and after inactivity, but does not report the values or say how the measurements were combined in an analysis. It would therefore be inappropriate to claim that a particular paired analysis was performed.

What does a standard deviation describe?

In general, a standard deviation describes variation among observations around their mean. It is not the same as the uncertainty of the estimated mean. A confidence interval is a way to express estimation uncertainty: it gives a range of values compatible with the data and the method used, under its assumptions. A narrow interval indicates greater precision than a wide interval, but the record contains no confidence interval for the primary outcome. Without the estimates and their uncertainty, neither the magnitude nor precision of the reported endpoint can be assessed.

Why does the single-group structure matter?

In general, a within-person design can account for stable differences between people when the analysis compares measurements from the same individuals. However, a single group measured at different times does not have a concurrent control group. Changes over time may reflect the activity sequence, measurement conditions, or other factors that change during the study. Random assignment to a separate comparison condition can help address some competing explanations, but the record lists allocation as NA and describes a single group. The record does not report an analysis intended to isolate the effect of activity from other time-related influences.

What can a significance test establish?

In general, a significance test evaluates how compatible the data are with a specified null hypothesis under the test’s assumptions. A p-value is not the probability that the null hypothesis is true, nor is it a measure of clinical importance. Interpretation should consider the estimated effect and its confidence interval, along with the design and the measurement. The registry record reports no p-value, confidence interval, or test for the primary outcome, so statistical significance cannot be assessed from the record.

Why might over-dispersion matter?

In general, over-dispersion occurs when data vary more than a statistical model assumes. If a model understates that variability, standard errors may be too small and uncertainty may appear less than it is. The endpoint in this study is described as continuous, and the record does not report a model, distributional assessment, or evidence of over-dispersion. This is a general consideration, not a claim that over-dispersion occurred in this study.

How should sample-size planning be read?

The registry’s planning assumptions describe a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and effects framed as fractions of the observed effect. These are planning assumptions, not a description of the study’s single-group design. The record does not report the observed effect needed to interpret such planning figures, and the figures are not evidence of the study’s actual power. In general, planning calculations depend on the target effect, variability, analysis method, and design assumptions. A planning illustration cannot substitute for an estimate from observed data.

The registry record lists no analyses. It does not report a model specification, an analysis population, missing-data method, confidence-interval method, or multiplicity adjustment. These absences mean that the statistical approach and its assumptions cannot be independently evaluated from the record. They do not establish what analyses may have been carried out outside the registry.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Exercise")
n   <- c(13)
m   <- c(0)
sp  <- c(3)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Exercise  13  0.000  3.000  -1.813  1.813

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists one primary outcome measure and no statistical analyses. It does not report a multiplicity plan, including whether there were additional outcomes, time points, or comparisons that were considered in a formal analysis. The summary discusses both the effect of inactivity and a possible response after return to activity, but the record does not state how these questions were prioritized or whether any adjustment for multiple testing was planned. A multiplicity procedure cannot be inferred from the presence of a primary outcome alone.

In general, when several hypotheses are tested, the chance of at least one false-positive result can increase if each is judged using the same unadjusted threshold. Adjustment methods can address that issue, but which method is appropriate depends on the planned family of comparisons. Since no analysis or multiplicity strategy is reported, it is not possible to assess how this issue was handled in this study.

The registry record also does not report missing outcome measurements, the number of participants included in an outcome analysis, or an analysis population definition. It does not describe imputation, exclusion rules, or a sensitivity analysis for missing data. These details matter because missing measurements can affect both the estimate and its uncertainty, particularly when missingness is related to participants’ outcomes or study conditions. No particular missing-data problem can be asserted from the absence of reporting.

In general, an analysis population specifies which participants contribute to a particular estimate and under what rules. The record lists enrollment of 13, but does not state how many contributed measurements at each time point or how the analysis population was defined. Enrollment alone should not be treated as the number analyzed. The registry record’s lack of analysis details limits assessment of the endpoint methods without establishing that a particular procedure was or was not used outside the record.

12. Safety Results

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

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 00% reporting threshold.

The registry record lists 13 participants at risk for serious adverse events and 0 with a serious adverse event. It also lists 13 at risk for other adverse events and 0 with another adverse event. These are the recorded figures for the Exercise group. The deaths field is not reported in the registry record.

In general, an at-risk count is the number of participants included in the safety accounting for a specified category, while the affected count records participants with an event in that category. The posted figures should be read as safety reporting for this study, not as proof that an event is impossible or that the intervention has no risk. A zero recorded count does not describe what might occur in a larger or different population, and the registry record does not provide further event details or an observation period specific to safety.

The study is single-group and has no like-for-like control group. Consequently, the safety entries do not provide a comparative estimate of event frequency between activity conditions or against a separate control. They are descriptive registry counts. The unreported deaths field should not be interpreted as a recorded count of zero.

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

The registry record establishes that investigators planned to examine whether reduced activity altered post-meal blood flow in healthy, young, active men, and whether a return to activity could restore the response. It describes an activity sequence, Doppler ultrasound measurement during an oral glucose tolerance test, and a continuous primary endpoint expressed as percentage of change in blood flow. These details explain the research question and the kind of physiological outcome that was measured.

The record does not report the primary outcome results. It therefore does not show whether inactivity was followed by a change in blood flow, how large any change was, or how precisely it was estimated. The record also does not give numerical results after the return-to-activity period. No conclusion about restoration can be drawn from the outcome information listed.

Even if numerical within-group changes were available, a single-group sequence would not offer the same evidence as a randomized comparison with a concurrent control. In general, repeated measurements in one group can describe change over time, but they cannot by themselves distinguish the activity sequence from every other factor that might vary over time. The registry record does not report a control group or statistical adjustment for such factors.

The endpoint is a measure of blood-flow response, described as a marker of vascular health. A marker is not itself a complete account of overall health or a clinical outcome. The record does not report evidence about longer-term health outcomes, nor does it provide results that could support conclusions beyond the described measurement and population. The listed condition of insulin resistance should not be treated as evidence that the participants all had that condition.

Accordingly, the most defensible reading is that this record documents a focused physiological research question and study schedule, while leaving the primary findings and their uncertainty unreported. The absence of those results limits what can be said about the observed data. It is not evidence that there was no effect, just as the study question is not evidence that an effect occurred.

14. Why This Trial Matters Statistically

This study is statistically useful to consider because its central question concerns a change across conditions within a single group. Such designs raise important questions about the relationship between repeated measurements, variability within participants, and changes over time. For a continuous endpoint such as percentage of change in blood flow, interpretation depends not only on a group average but also on the spread of values and the uncertainty around the estimate.

The registry record makes clear that the design is single-group and that allocation is NA. This matters because a before-and-after difference is not automatically a causal estimate. In general, a concurrent comparison group can help distinguish a change associated with the study condition from changes that occur over time for other reasons. Without such a group, interpretation needs to remain tied to the observed sequence and the limitations of that design.

The record also illustrates why reporting the result matters as much as describing the endpoint. The mean and standard deviation are identified as intended summaries, but no values or analysis are listed. Without estimates, uncertainty measures, and analysis details, readers cannot evaluate magnitude, precision, or compatibility with alternative explanations. The biological question may be clear while the statistical evidence remains unavailable in the registry record.

Finally, the planning assumptions described in the record use equal allocation between two arms, while the study itself is identified as single-group. Planning calculations are sensitive to design assumptions, and an illustration based on an observed effect is not a substitute for an outcome estimate. Keeping the planning scenario distinct from the completed study prevents readers from mistaking hypothetical sample-size calculations for evidence about what the study observed or how reliably it estimated change.

15. 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 most direct limitation for interpreting this study is that the registry record does not report numerical primary outcome results. There is no mean, standard deviation, effect estimate, confidence interval, or p-value for the blood-flow endpoint. Without these, readers cannot judge the direction, magnitude, or precision of the observed change.

The single-group structure also limits causal interpretation. Measurements before and after inactivity can describe change over the study sequence, but the record lists no concurrent control group. It does not report random allocation or an adjustment method that would distinguish activity-related change from other changes over time.

The record describes the return-to-activity period in two ways: the intervention description specifies a 1 day return, while the primary outcome description refers to 1.5-2 days. It does not explain that difference. The primary outcome description identifies measurements before and after inactivity, but the record does not provide results for the return period or clarify how restoration was assessed.

Further statistical details are not reported in the registry record. These include the analysis method, the handling of missing measurements, the analysis population, and any multiplicity plan. Their absence limits assessment of the analysis but does not establish that these procedures were not conducted outside the registry. The record also does not report a sample-size justification. The planning assumptions described are an illustration, not evidence about the study’s original design rationale or observed power.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: The Effects of Altering Physical Activity on Cardiometabolic Health — NCT01879059.
• Registry record last updated 2016-02-08; status last verified 2016-01.
• Results first posted 2016-02-08.
• 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.

19. Record Summary

NCT01879059, titled The Effects of Altering Physical Activity on Cardiometabolic Health, is listed as COMPLETED and sponsored by the University of Kansas Medical Center. The record lists enrollment of 13, a SINGLE GROUP model, allocation as NA, and masking as NONE. The intervention description specifies 5 days of inactivity followed by a 1 day return to physical activity.

The primary outcome is percentage of change in blood flow, measured by Doppler ultrasound during an oral glucose tolerance test before and after inactivity. Its stated timeframe is 10 days, and the record identifies the mean and standard deviation as the summary parameter and dispersion measure. The population description is healthy, young, active men.

The registry record lists no statistical analyses and does not report the primary outcome results. It also does not report a multiplicity plan, missing-data approach, analysis population, or sample-size justification. The safety record lists 0 serious and 0 other adverse events among 13 at risk in the Exercise group; the deaths field is not reported.