High Intensity Interval Exercise SCI: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for High Intensity Interval Exercise SCI (NCT04940598), a randomized na study. The primary outcome is Aerobic Capacity Baseline.

2. Clinical Question

3. Trial Design

The registry describes a completed, randomized, parallel-group study with no masking. Enrollment is 8. The listed intervention arms are high-intensity interval exercise and no-exercise control; the arm descriptions specify high-intensity interval arm-crank exercise and a no-exercise control group. The record gives an arm count of 5 for the exercise group and 3 for the control group. These are the reported arm counts; the record does not provide a participant flow account explaining screening, allocation, follow-up, or exclusions.

The study summary describes a home-based telehealth exercise-training program for individuals with longstanding spinal cord injury. It states that the study aims to assess feasibility, enjoyment, and potential health impact, including cardiometabolic health and physical function. The registry entry identifies the primary outcome as aerobic capacity at baseline, with a mean and standard deviation as the planned summary format. The baseline measurement is not itself a treatment-effect estimate. No post-intervention primary outcome analysis is posted.

The record lists 14 outcome measures and 0 analyses. It does not report the statistical analysis plan, allocation concealment, masking of outcome assessors, adherence, or reasons for withdrawal. The study start is recorded as 2021-02-01, primary completion as 2023-07-31, and status as completed. These dates describe the registry record and do not establish how long each participant was followed. The phase is listed as NA. The protocol’s sample-size justification and any interim analyses are not reported in the registry record.

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

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 Aerobic Capacity Baseline, measured over baseline.

The primary outcome is aerobic capacity at baseline, reported in ml/kg/min. The registry defines the measure using a progressive peak oxygen assessment on an arm-crank ergometer. The description says participants begin at 10W for 2 min and that power output increases by 10W every 2 min until voluntary fatigue. Peak aerobic power is defined as VO2 at the point when the participant cannot maintain 60-65 rotations per minute. These are the measurement procedures described in the record; they are not an analysis of treatment response.

Aerobic capacity is a continuous measure, and the registry identifies the summary as a mean with standard deviation. In general, this type of measure provides a numerical description of participants’ exercise capacity, while the standard deviation describes spread around the group mean. Such a measure can be relevant to a study of physical function and cardiometabolic health. The record does not explain why this measure was selected as the primary outcome, nor does it report a baseline-adjusted or follow-up treatment comparison.

The posted values are 11.6 with a standard deviation of 2.9 for the exercise arm and 10.0 with a standard deviation of 0.99 for the no-exercise control arm. They characterize baseline groups only. The registry record does not report follow-up values, change scores, or a treatment-effect estimate for this outcome.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The available primary outcome is continuous: aerobic capacity is summarized using a mean and standard deviation. These statistics describe the observed baseline measurements within each arm. A mean gives the central value of a group’s observations; a standard deviation describes how dispersed those observations are around that mean. Neither statistic, on its own, estimates the effect of the intervention. For an intervention effect, the analysis would need to compare outcomes in a way that accounts for the study’s allocation and the timing of measurement.

What does the baseline summary tell us?

The exercise group’s baseline mean is 11.6 ml/kg/min, with a standard deviation of 2.9; the control group’s baseline mean is 10.0 ml/kg/min, with a standard deviation of 0.99. The reported group counts are 5 and 3. These numbers describe the baseline outcome distributions in the two arms as recorded. They do not show what happened after participants undertook the exercise program, and they do not establish that assignment to exercise caused any difference. Baseline comparisons can describe the groups, but the registry record does not report a formal baseline comparison or an analysis adjusting for baseline values.

Why is an outcome comparison needed?

In general, randomized allocation is intended to support a fair comparison of outcomes between groups. A treatment-effect analysis would need a defined follow-up outcome or change measure and an analysis appropriate to the study design. Depending on the planned approach, this might compare follow-up measurements or compare changes from baseline. The registry record does not report which method was planned, whether follow-up measurements were collected, or whether an adjusted model was used. No treatment-effect estimate or uncertainty interval is posted, so the baseline summaries cannot substitute for that missing analysis.

What does a confidence interval represent?

In general, a confidence interval expresses uncertainty around an estimated effect under the assumptions of the analysis. A narrower interval indicates greater precision under those assumptions, while a wider interval indicates greater uncertainty. It does not guarantee that the true effect lies within the particular interval, nor does it resolve concerns about bias or incomplete data. No confidence interval for an intervention effect is reported in the registry record. The available means and standard deviations alone are insufficient to report the precision of a treatment comparison without choosing and carrying out an analysis.

Why can a small study be hard to interpret?

In general, estimates from small studies can be imprecise because each observation has substantial influence on group summaries. Results can also be sensitive to unusual observations and to differences between participants at baseline. The arm counts recorded are 5 and 3, so the posted summaries represent small groups. This observation is about the information available for interpretation; it does not establish that any particular estimate is biased or that an effect is absent. The registry does not report a sample-size justification, and there is no basis in the posted results for asserting that the study was adequately powered for a specific treatment effect.

How should planning calculations be read?

In general, sample-size planning calculations describe how many participants per arm might be needed under stated assumptions to detect a specified effect with a chosen statistical approach. They are design illustrations, not observed outcomes and not evidence that a completed study had a particular probability of detecting an effect. The registry’s planning assumptions specify a two-sided significance level of 0.05, equal allocation, and a normal approximation, with the effect expressed as a fraction of the observed effect. These assumptions do not establish the protocol’s original design rationale. The record does not report that rationale. The primary comparison is marked as not estimable from the posted continuous endpoint values, so no treatment-effect planning illustration should be interpreted as an estimate of the result.

In general, over-dispersion means that data vary more than a statistical model assumes. When present, it can make standard errors too small if the analysis ignores it, leading to intervals that are too narrow and tests that are too optimistic. The record does not report an over-dispersion assessment or a model for the primary outcome. Given the continuous baseline summary and absence of a posted analysis, over-dispersion is a general statistical consideration rather than a reported feature of this study.

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("High Intensity Interval Exercise", "No-Exercise Control")
n   <- c(5, 3)
m   <- c(11.6, 10)
sp  <- c(2.9, 0.99)
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  High Intensity Interval Exercise  5  11.600  2.900  7.999  15.201
CARM  No-Exercise Control  3  10.000  0.990  7.541  12.459

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 14 outcome measures and 0 analyses. It does not report a multiplicity adjustment, a hierarchy of outcomes, a prespecified set of confirmatory comparisons, or an analysis plan. When a study examines several outcomes or comparisons, multiplicity can increase the chance that at least one apparently notable result arises by chance. In general, an analysis plan may address that issue by identifying primary comparisons in advance or applying an appropriate adjustment. Whether such methods were planned or used is not reported in the registry record.

The record does not provide information on missing outcome data, participant withdrawals, adherence, or how the analysis population was defined. It is therefore not possible to determine from the posted results whether analyses included all randomized participants, only participants with observed measurements, or another group. The registry also does not describe imputation, sensitivity analyses, or reasons for missingness. These details matter because missing data can affect both the estimated effect and its uncertainty, particularly when missingness differs between arms or relates to outcomes.

The baseline means and standard deviations are available, but no post-intervention comparison is posted. No missing-data method or multiplicity procedure can be inferred from those baseline summaries. The absence of a posted analysis should not be interpreted as evidence that the study performed no analysis outside the registry; it means that an analysis is not reported in the registry record.

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 reports serious adverse events for the high-intensity interval exercise arm as 0 among 5 at risk, and for the no-exercise control arm as 0 among 3 at risk. The reported other adverse-event counts are also 0 among 5 at risk in the exercise arm and 0 among 3 at risk in the control arm. Deaths are reported as 0 in both groups. No serious adverse event terms are listed.

These are the counts recorded in the registry. A zero count means that no event of the specified type was recorded for the stated group in the posted safety results; it does not establish that an event is impossible or that the intervention is risk-free. Safety counts from small groups provide limited information about uncommon events. The record does not report additional details about how adverse events were solicited, how long participants were monitored for safety, or whether all participants contributed safety follow-up for the same period. The counts therefore describe the posted safety record and should not be interpreted as a comprehensive estimate of risk.

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

The posted results establish that the registry records a completed randomized parallel-group study of high-intensity interval arm-crank exercise compared with a no-exercise control in individuals with longstanding spinal cord injury. Enrollment is 8, and the primary outcome entry reports baseline aerobic capacity as a mean and standard deviation. The safety entry records no serious adverse events, other adverse events, or deaths in either arm.

The results do not establish whether the exercise program changed aerobic capacity, cardiometabolic health, or physical function. The primary outcome is explicitly recorded at baseline, and no follow-up values or between-group treatment-effect analysis are posted. There is no reported confidence interval or p-value for a treatment comparison. The study summary describes intended questions about feasibility, enjoyment, and health impact, but the registry record does not post results for those questions.

In general, a completed study can still have results that are not posted in the registry record. The absence of a posted analysis does not prove that no data were collected or that no analysis was conducted elsewhere; it limits what can be concluded from this record. Likewise, the absence of recorded adverse events in the posted counts does not prove the absence of risk. The small reported arm counts and missing follow-up and analysis details constrain interpretation, without showing that an effect is absent or present.

The appropriate reading is therefore descriptive: the record gives baseline group summaries and reported adverse-event counts, but not an estimate of the intervention’s effect. It cannot support a conclusion about benefit, lack of benefit, or the precision of a treatment effect.

14. Why This Trial Matters Statistically

This study is statistically relevant because its registry entry makes a distinction between a trial’s stated aims and the outcome data actually posted. The study summary describes goals related to feasibility, enjoyment, cardiometabolic health, and physical function. The listed primary outcome, however, is aerobic capacity at baseline. A baseline measure can characterize participants and describe groups, but it cannot answer whether an intervention changed an outcome over time.

The record also illustrates why summaries need to be read alongside the analysis status. Means and standard deviations are useful descriptive statistics, yet they are not a substitute for a treatment-effect estimate and its uncertainty. Here, the registry lists 0 analyses and does not report a follow-up comparison, confidence interval, or p-value. That distinction is central to sound interpretation: the presence of numerical outcome data does not by itself establish an intervention result.

Enrollment and arm counts are also important context for precision. The posted groups are small, and the registry does not provide a sample-size justification or analysis plan. General statistical principles indicate that estimates from small groups may be uncertain, but the available record does not quantify that uncertainty for a treatment effect. Planning calculations, where considered, must remain illustrations under assumptions rather than evidence of observed power or evidence that a treatment effect was detected.

Finally, the safety record is a count summary, not a guarantee of safety. Its value is in transparent reporting of the recorded events and the group counts at risk. The study is a useful example of why statistical interpretation depends not only on the outcome values but also on timing, analysis methods, missing-data handling, and precision—all of which are incomplete or 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.

Several limitations of interpretation follow directly from the posted registry information. The primary outcome is baseline aerobic capacity, not an explicitly reported post-intervention outcome. No treatment-effect estimate is posted, and the record lists 0 analyses. As a result, the available data do not support an inference about change over time or a comparison of the exercise program with the no-exercise control.

The registry does not report follow-up measurements, participant flow, withdrawals, adherence, or the analysis population. It also does not report missing-data methods, a statistical analysis plan, multiplicity procedures, or a sample-size justification. Without these details, readers cannot assess how the reported analyses were defined or whether missing observations might affect results. The record lists 14 outcome measures, but does not provide analyses for them.

The arm counts are 5 and 3, which limits the amount of information in the group summaries. The registry provides means and standard deviations but no confidence intervals for a treatment effect. Because there is no posted effect estimate, precision cannot be evaluated for the intervention comparison. No additional participant characteristics are included in the primary outcome entry, so the extent to which these groups reflect a broader population with spinal cord injury cannot be assessed from this record.

The safety summary reports zero events in each listed category, but the registry does not report monitoring duration or further event-collection details. These omissions limit interpretation of both effectiveness and safety. They do not demonstrate that the study found no effect, that no data were collected, or that an unreported method was not used; they identify what is not reported in the registry record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: High Intensity Interval Exercise SCI — NCT04940598.
• Registry record last updated 2024-07-24; status last verified 2024-07.
• Results first posted 2024-07-24.
• 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 record describes a completed randomized, non-masked, parallel-group study of home-based telehealth high-intensity interval exercise in people with longstanding spinal cord injury. The comparator is a no-exercise control group. Enrollment is 8, with 5 participants listed in the exercise arm and 3 in the control arm.

The primary outcome is baseline aerobic capacity in ml/kg/min, summarized by mean and standard deviation. The recorded means are 11.6 for exercise and 10.0 for control. The registry lists 14 outcome measures and 0 analyses; no follow-up treatment comparison, confidence interval, or p-value is reported. Serious and other adverse-event counts, and deaths, are recorded as 0 in both arms. The registry record does not report the analysis plan, missing-data handling, or sample-size justification. Thus, the posted information provides baseline and safety descriptions but not an estimate of treatment effect.