Health Effects of Increasing Muscle Activation While Sitting in Office Workers: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Health Effects of Increasing Muscle Activation While Sitting in Office Workers (NCT02855541), a na na study. The primary outcome is Blood Glucose.

2. Clinical Question

The registry describes a study asking whether regularly interrupting sitting at work with a small cycling device is associated with changes in cardiometabolic risk factors among office workers whose jobs involve prolonged sitting. Its stated hypothesis is that breaking up sitting will be associated with lower blood glucose during an oral glucose tolerance test, higher cardiorespiratory fitness, lower blood pressure and body fat, higher HDL cholesterol, and lower LDL cholesterol, total cholesterol, and triglycerides.

The primary outcome is blood glucose measured in mmol/L. The outcome description specifies the post-test measurement, while the registry’s stated hypotheses cover additional risk factors. Without a listed control group or posted outcome values, the record cannot establish how participants’ measurements changed relative to an untreated group or whether any of the hypotheses were supported.

3. Trial Design

The registry classifies this as a single-group study of a device intervention. Allocation is listed as NA, masking as NONE, and phase as NA. The record is marked completed and lists an enrollment of 25. The sponsor is the University of Colorado, Boulder. The listed study dates are 2016-08 for study start and 2017-06 for primary completion.

Participants in the cycling intervention were to use DeskCycle at their workstations for 15 minutes every hour they were at work. The primary endpoint is described as 2-h post oral glucose tolerance test blood glucose, measured after 4 weeks. The registry lists systolic blood pressure, HDL cholesterol, LDL cholesterol, triglycerides, lean mass, and fat mass as secondary outcomes. It also describes hypotheses concerning cardiorespiratory fitness, total cholesterol, and body fat, but detailed outcome results are not reported in the registry record.

A single-group design does not provide a concurrent control group for separating changes associated with the intervention from changes that could occur over time for other reasons. The registry specifically notes that this is not a randomized comparison and that any arms are not a like-for-like control comparison. The record does not report further design details such as the measurement schedule beyond the primary endpoint timeframe, adherence to device use, or the way measurements were compared over time.

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:

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 Blood Glucose, measured over Measured after 4 weeks.

The primary endpoint is blood glucose in mmol/L, recorded as a mean with standard deviation. Its description specifies blood glucose measured 2 hours after an oral glucose tolerance test, with the primary measurement timeframe listed as after 4 weeks. An oral glucose tolerance test assesses blood glucose following a glucose challenge; the specified post-test time point makes clear which measurement the endpoint concerns.

In general, a continuous endpoint such as blood glucose can be summarized by a mean to describe the group’s average measurement and by a standard deviation to describe the spread of individual measurements around that average. The standard deviation is not a measure of uncertainty in the estimated mean; it describes variability among measurements. A confidence interval, if reported, would address uncertainty in an estimated quantity, but no endpoint estimate or confidence interval is reported in the registry record.

The registry’s stated rationale is to examine potential health benefits of breaking up sitting in a real-world work environment. Blood glucose is the primary outcome, while the record also lists several secondary outcomes related to blood pressure, blood lipids, and body composition. The endpoint definition alone does not show whether blood glucose changed, how large any change was, or how precisely it was estimated. Those results are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does the reported outcome format mean?

The primary endpoint is a continuous measure: blood glucose in mmol/L, summarized as a mean and standard deviation. In general, the mean describes the average observed value. The standard deviation describes how dispersed the observations are around that average. These answer different questions: the mean locates the group average, while the standard deviation describes variation among individual measurements. Neither statistic alone establishes whether a group changed from an earlier measurement or differed from a comparator.

In general, uncertainty in an estimated mean or contrast is described with a confidence interval. A confidence interval communicates the range of effect estimates that are reasonably compatible with the data and analysis assumptions. It is not the same as the spread of individual values. No confidence interval or outcome estimate is reported in the registry record, so the precision of the primary endpoint cannot be assessed from the posted results.

What can a single-group design estimate?

The registry lists a single-group model and no randomized comparator. A single-group study can describe measurements in the participants who were observed, but interpretation of change depends on having appropriate measurements and a clearly stated analysis. Even when before-and-after measurements are available, a change over time does not by itself distinguish an intervention-associated change from other time-related influences. The registry record does not report the measurement schedule or the statistical comparison used for the primary endpoint.

Random allocation, when used, can help make comparison groups comparable on average at the start of a study. That general feature does not apply as a reported comparison in this record: allocation is NA, and the registry notes that this is not a randomized comparison. No control-group outcome is listed. Consequently, a treatment contrast against a concurrent control cannot be interpreted from the registry entry.

Why do variability and sample size matter?

In general, the precision of an estimate depends on the amount of information in the data and the variability of the outcome. A standard deviation helps describe the latter, while the number of participants with usable outcome measurements contributes to the former. The registry lists an enrollment of 25, but does not report the number included in each outcome analysis or the endpoint’s observed variability. The precision of an effect estimate therefore cannot be inferred from enrollment alone.

Over-dispersion is a general concern when variability in observed data is greater than a statistical model assumes. If a method assumes less variability than is present, its uncertainty estimates can be too small and its results can appear more precise than warranted. The registry record does not report a model, a dispersion assessment, or an analysis that would allow this issue to be evaluated for these outcomes.

The associated sample-size calculations are planning illustrations using the stated assumptions: a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect defined as a stated fraction of an observed effect. The record says these calculations are not the trial’s own design. Such calculations describe hypothetical planning requirements under assumptions; they are not observed power and do not substitute for reported outcome estimates. No numerical sample-size illustration or observed effect is reported in the registry record.

What would a statistical test tell the reader?

In general, a statistical test evaluates how compatible the observed data are with a specified null hypothesis under the model assumptions. A p-value does not measure the size or clinical importance of an effect, and it does not give the probability that a hypothesis is true. Effect estimates and confidence intervals are needed to communicate magnitude and precision. The registry lists 0 analyses, so no test statistic or p-value is reported for this study.

Good interpretation also depends on knowing the exact analysis population, outcome definition, handling of missing observations, and any adjustments or transformations. Those details are not reported in the registry record. The endpoint is defined as a mean of a continuous measure, but the record does not provide enough analysis information to reconstruct or evaluate an inferential method.

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("Cycling Intervention")
n   <- c(21)
m   <- c(5.6)
sp  <- c(1.23)
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  Cycling Intervention  21  5.600  1.230  5.040  6.160

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 8 outcome measures and identifies blood glucose as the primary outcome. It also lists secondary outcomes related to systolic blood pressure, HDL cholesterol, LDL cholesterol, triglycerides, lean mass, and fat mass. The study description states additional hypotheses, including cardiorespiratory fitness and cholesterol measures. The registry does not report how many outcomes were included in formal statistical testing or whether a primary testing hierarchy was specified.

In general, multiplicity arises when several hypotheses are tested. The more tests conducted, the greater the chance that at least one result may appear notable by chance if each test is considered separately. Methods such as prespecifying a primary outcome or adjusting inference can address this issue, but the registry record does not report a multiplicity procedure or analysis plan. No analyses are listed, so the actual testing strategy cannot be assessed.

Missing-data handling is also not reported in the registry record. The enrollment is 25, but the number with usable measurements for each outcome, reasons for missing observations, and any imputation or other handling method are not specified. Without those details, it is not possible to determine whether outcome summaries would represent all enrolled participants or a subset.

The record does not report analysis populations, such as whether all enrolled participants or only participants with particular follow-up measurements were included. It also does not report a statistical analysis plan, interim analyses, or methods for handling deviations from the intervention. These omissions limit assessment of how outcomes were selected, analyzed, and interpreted; they do not establish that any particular method was or was not used.

12. 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 0% reporting threshold.

The registry records one cycling intervention group. It lists 25 participants at risk for serious adverse events and 25 at risk for other adverse events. The recorded number affected is 0 for serious adverse events and 0 for other adverse events; deaths are also recorded as 0. No top serious adverse-event terms are listed.

These figures describe what is entered in the registry for the listed group. A recorded zero means that no affected participants are reported in that category in this entry; it is not proof that an event is impossible or that every possible event was captured. The record does not provide event descriptions, follow-up detail, or an account of how adverse events were monitored. It also has no comparator group, so the safety figures do not provide a comparative estimate between intervention and control.

The registry’s safety counts should be read separately from the missing efficacy results. They do not report whether blood glucose or the other outcomes changed. The posted safety information is limited to the listed counts and should not be extended beyond those recorded categories.

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

The registry record documents a completed study of a workday cycling intervention in office workers with prolonged sitting. It identifies DeskCycle use for 15 minutes every hour at work and names blood glucose after an oral glucose tolerance test as the primary outcome, measured after 4 weeks. The record also identifies several secondary outcomes and states hypotheses about cardiometabolic risk factors.

It does not report outcome estimates, standard deviations, confidence intervals, or statistical test results. As a result, the posted results do not show the magnitude or precision of any change in blood glucose or other outcome. The hypotheses in the study description should be understood as questions the investigators intended to examine, not as findings.

The single-group design further limits what could be concluded about cause and effect. With no listed concurrent control group or randomized comparison, an observed change, if available, could not by itself establish that the intervention caused that change. The registry record also does not report analysis populations, missing-data handling, or a statistical analysis plan, which would be needed to assess the basis and robustness of any estimates.

Accordingly, the record supports a description of the study’s intervention, endpoint, and design, but not a conclusion about whether the intervention changed cardiometabolic measures. The absence of outcome results in the registry record is not evidence that the outcomes did or did not change.

14. Why This Trial Matters Statistically

This trial raises a useful statistical distinction between documenting a health question and providing evidence that answers it. The registry gives a specific intervention schedule, a defined primary measure, and a follow-up timeframe. Those details make the intended question understandable. But without numerical outcome estimates and their uncertainty, readers cannot assess the size or precision of any association.

The design also makes the comparator question central. A single-group study can describe what was observed in its participants, but it does not offer a randomized, concurrent comparison for separating intervention-associated changes from other changes over time. This is an important issue when the stated aim concerns potential health benefits rather than simply feasibility or measurement.

The record lists multiple outcomes and hypotheses. In general, interpreting several outcomes requires clarity about which is primary and how the analysis accounts for multiple testing. The registry identifies a primary endpoint, but does not report a multiplicity approach or analysis results. This illustrates why outcome definitions and statistical plans are important complements to a list of hypotheses.

Finally, enrollment is not a substitute for the analysis denominator or for effect estimates. Knowing that 25 participants were enrolled does not establish how many contributed endpoint data or how precisely the primary outcome was estimated. Statistical interpretation depends on the observed measurements, their variability, and the analysis used. Those results and details are not reported in the registry record.

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 is that outcome results are not reported in the registry record. There is no primary endpoint mean or standard deviation, no estimate of change, and no confidence interval or test result. The study’s stated hypotheses therefore cannot be evaluated from the posted results.

The registry identifies a single-group model and no randomized comparison. This leaves no concurrent control outcome for interpreting changes over time. The record does not describe a baseline measurement or the statistical comparison used, so it is not possible to determine from the entry how change was assessed.

The enrollment is 25, but the number of participants contributing to each outcome is not reported. Missing-data methods, analysis populations, adherence to the hourly device-use schedule, and participant-level outcome data are also not reported in the registry record. These details matter for understanding which observations inform any estimate and how representative the analyzed group may be.

The registry lists multiple outcome measures and hypotheses but does not report a statistical analysis plan, the approach to multiplicity, or any analyses. The intervention description specifies DeskCycle use at work, but the record does not provide results that would establish whether participants followed that schedule. Finally, the safety entry lists zero affected participants for the recorded serious and other adverse-event categories, but provides no further monitoring or event-capture detail. These limitations constrain what can be concluded from the registry entry; they do not establish that unreported procedures or data were absent from the study itself.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Health Effects of Increasing Muscle Activation While Sitting in Office Workers — NCT02855541.
• Registry record last updated 2018-11-13; status last verified 2018-11.
• Results first posted 2018-11-13.
• 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

The registry identifies NCT02855541 as a completed, single-group study sponsored by the University of Colorado, Boulder. It lists an enrollment of 25, allocation as NA, masking as NONE, and phase as NA. The listed start and primary completion are 2016-08 and 2017-06.

The intervention was workstation use of DeskCycle for 15 minutes every hour at work. The primary outcome was mean blood glucose in mmol/L, described as 2-h post oral glucose tolerance test blood glucose measured after 4 weeks. Secondary outcomes include systolic blood pressure, HDL cholesterol, LDL cholesterol, triglycerides, lean mass, and fat mass.

The registry record does not report outcome estimates or statistical analyses. It lists 0 analyses and records 0 affected participants for serious adverse events, 0 for other adverse events, and 0 deaths in the intervention group.