The Effects of Swimming on Elderly Women With Stage-2 Hypertension: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for The Effects of Swimming on Elderly Women With Stage-2 Hypertension (NCT03546270), a randomized na study. The primary outcome is Arterial Stiffness.

2. Clinical Question

3. Trial Design

The registry describes a randomized, single-masked, parallel-group trial with an enrollment of 100. The groups were swimming and control. At the posted primary endpoint, the swimming group has 52 participants and the control group has 48. Enrollment and endpoint group sizes are not necessarily interchangeable: the registry does not explain whether any participants withdrew, were excluded from an analysis, or had missing measurements.

The swimming program was planned to last 20 weeks. Its description names free style, breast stroke, and backstroke, and gives training details for the first 5 weeks: 25-30 minutes/day, 3-4 days/week, at approximately 60% of maximal heart rate. The description then indicates that intensity and duration changed as fitness and exercise skill improved, but the remainder of the training schedule is not reported in the registry record. The control group did not participate in a supervised exercise program. Control participants visited the laboratory at the same frequency and took part in recreational activities such as board games.

The registry marks masking as single but does not specify who was masked or how masking was maintained. Allocation is identified as randomized, but the randomization sequence, allocation concealment, and implementation details are not reported in the registry record. The record lists the trial as completed, with a start of 2017-01 and primary completion of 2018-01. It identifies Pusan National University as the sponsor and lists the phase as NA.

The brief summary describes measurements of arterial stiffness, blood pressure, wave reflection, muscle strength, and aerobic capacity. Six outcome measures are listed, including the primary measure, but only three secondary outcomes have numerical group results posted. The registry's own analysis methods and sample-size justification 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 Arterial Stiffness, measured over 20-weeks.

The primary endpoint is arterial stiffness at 20 weeks, measured through pulse wave velocity and expressed in m/s. Pulse wave velocity measures how quickly a pressure wave travels through the arterial system. It is used as an indicator of arterial stiffness because the speed of wave travel is related to the mechanical properties of the arteries. This is a general description of the measure, not an additional finding from the trial.

The posted endpoint is a mean with standard deviation for each group. The swimming group mean is 7.8 m/s, with a standard deviation of 0.3, and the control group mean is 10.0 m/s, with a standard deviation of 0.2. The recalculated unadjusted mean difference, expressed as swimming minus control, is -2.2 m/s. Its confidence interval ranges from -2.299 to -2.101, and the unadjusted p-value is < 0.001.

A group mean describes the average measurement among participants included in that group’s posted result; it does not show how measurements were distributed across individuals. The standard deviation describes variability within a group, not the precision of the group mean. The registry does not report baseline pulse wave velocity values, participant-level data, or details about the method used to obtain the measurements. It also does not report whether the posted comparison adjusts for baseline values or other variables.

7. Results Posted in the Registry

• Swimming: mean 7.80 versus 10.00 on control; difference -2.20 (95% CI -2.30 to -2.10), standardized effect d = -8.56; z-test p = <0.001.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Systolic Blood Pressure

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Swimming: mean 135.00 versus 145.00 on control; difference -10.00 (95% CI -10.39 to -9.61), standardized effect d = -10.00; z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically lower for Swimming than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Pressure Wave Reflection

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Swimming: mean 25.00 versus 31.00 on control; difference -6.00 (95% CI -6.78 to -5.22), standardized effect d = -3.00; z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically lower for Swimming than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Muscular Strength

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Swimming: mean 27.00 versus 24.00 on control; difference 3.00 (95% CI 2.61 to 3.39), standardized effect d = 3.00; z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically higher for Swimming than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

The secondary outcomes with numerical group results show a directionally coherent pattern alongside the primary pulse wave velocity result. The posted swimming-group mean is lower for systolic blood pressure and pressure wave reflection, while muscular strength has a higher mean in the swimming group. In general, these outcomes describe related but distinct aspects of cardiovascular function and physical capacity; they are not interchangeable measures of arterial stiffness. Their pattern can be considered alongside the primary result, but it does not establish that changes in one measure caused changes in another.

The registry lists five secondary outcomes, but numerical results are posted for only three: systolic blood pressure, pressure wave reflection, and muscular strength. Numerical results for diastolic blood pressure and cardiorespiratory endurance are not reported in the registry record. This means the full pattern across all registered secondary outcomes cannot be assessed from the posted numerical results. The registry also does not report whether outcomes were selected for posting according to a prespecified plan.

The secondary comparisons have unadjusted p-values of < 0.001, but unadjusted significance does not account for the fact that several outcomes were assessed. When many outcomes are tested, some results may appear more notable by chance even if there are no corresponding underlying differences. General statistical approaches can control or organize this issue through multiplicity adjustment, a hierarchy of outcomes, or clear separation of confirmatory and exploratory analyses. Such procedures are not reported in the registry record.

Accordingly, the secondary results offer descriptive context for the primary endpoint rather than independent confirmation with the same evidential status. The unavailable secondary measurements, absent analysis plan, and lack of reported multiplicity handling make it difficult to determine which secondary findings were confirmatory. They should not be treated as proof of broad effects across every measured domain.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Systolic Blood Pressure
• Pressure Wave Reflection
• Muscular Strength
• Cardiorespiratory Endurance (Volume of Maximal Oxygen Consumption)
• Diastolic Blood Pressure

9. Statistical Interpretation

10. Statistical Methods Explained

What does a mean difference describe?

The primary measure is continuous, and the registry reports a mean and standard deviation for each group. The recalculated mean difference subtracts the control mean from the swimming mean. With this direction, a negative value means that the swimming group’s posted mean is lower; a positive value means it is higher. For pulse wave velocity, the group means are 7.8 m/s and 10.0 m/s, and the recalculated difference is -2.2 m/s. This is an unadjusted comparison of the posted endpoint summaries, not a change-from-baseline estimate.

A mean difference retains the original measurement units, making it possible to interpret the estimate on the scale used for the outcome. It does not describe the spread of individual responses or show whether every participant had a measurement near the group average. The standard deviations provide information about within-group variation, while the confidence interval for the mean difference describes uncertainty in the estimated group contrast. These are different quantities and should not be treated as interchangeable.

What does the confidence interval add?

A confidence interval gives a range of estimates compatible with the observed data and the calculation's assumptions. In repeated use of the same procedure under its assumptions, intervals constructed in this way would cover the underlying quantity at the stated confidence level. The primary interval, from -2.299 to -2.101 m/s, lies on the negative side of zero. This indicates that the recalculated unadjusted comparison is inconsistent with a zero mean difference under the method used. The interval does not account for unreported design or analysis issues, such as missing data, departures from randomization, or selective outcome reporting.

The registry does not give the trial's own statistical model or a sponsor-reported confidence interval. The posted comparison is therefore best understood as a simple unadjusted recalculation from the group summary statistics. In a randomized trial, a prespecified analysis may use additional information, such as baseline measurements or stratification variables. Whether the investigators used such methods is not reported in the registry record. The recalculated result should not be presented as though it were a documented adjusted analysis.

How should a p-value be read?

The primary unadjusted p-value is < 0.001. In general, a p-value describes how unusual a result at least as discrepant as the observed one would be if a specified null model held and the analysis assumptions were appropriate. It does not give the probability that the null hypothesis is true, the probability that the result occurred by chance, or the probability of a particular outcome for an individual. Nor does a small p-value establish that a difference is clinically important. The registry does not report a clinical-importance threshold for this measure.

The same unadjusted p-value notation appears for the three secondary outcomes with posted numerical comparisons. Because multiple outcomes are considered, the chance of at least one apparently notable result can rise when many comparisons are examined. General statistical practice may address this through a prespecified hierarchy or multiplicity adjustment. Neither a hierarchy nor an adjustment is reported in the registry record, so the secondary p-values should be read as unadjusted evidence for their individual comparisons.

Why does dispersion matter?

Standard deviation describes how much individual measurements vary around a group mean. The primary endpoint standard deviations are 0.3 in the swimming group and 0.2 in the control group. A standard deviation is not a standard error and does not directly quantify uncertainty in the difference between means. Standard errors depend on both the variability and the number of participants contributing data. The posted recalculation uses the group summaries and group sizes to estimate uncertainty in the mean difference.

For continuous outcomes, the usual mean-based comparison is most straightforward when the distributional and independence assumptions are reasonable. General statistical methods may need to account for skewness, outliers, repeated measurements, clustering, or unequal variance when these features are present. The registry does not report distributional checks or the method used in the trial's own analysis. It is therefore not possible to assess whether the simple unadjusted calculation matches the investigators' intended analysis or whether alternative modeling choices were considered.

What is and is not documented?

The registry identifies the trial as randomized, single-masked, and parallel-group, and gives the group summaries and endpoint timeframe. It does not report the randomization procedure, masking details, analysis population, missing-data method, baseline adjustment, or a prespecified statistical plan. It also does not report the trial's original sample-size justification or interim analyses. These absences do not prove that such procedures were not used; they mean that they cannot be evaluated from the registry record.

The registry lists no reported analyses, even though it posts group summary results and the comparisons used for the recalculations. This distinction matters: an outcome value is not a substitute for a fully specified analysis report. In general, a trial report would clarify which participants were included, how missing measurements were handled, whether the analysis followed randomized assignment, which covariates were included, and whether the final analysis followed the prespecified plan. Those details are not reported in the registry record, so the comparison should be interpreted as a descriptive, unadjusted estimate rather than a reconstruction of the complete trial analysis.

11. Confidence Intervals and Precision

The primary mean difference is -2.2 m/s, with a recalculated unadjusted confidence interval from -2.299 to -2.101. The interval is narrow relative to the point estimate and excludes zero. This indicates high numerical precision for this summary-statistic comparison under the assumptions of the recalculation. It does not mean that the estimate is free from bias, nor does it describe the range of individual participants’ measurements.

Precision concerns random uncertainty in an estimate. Bias concerns systematic departures from the quantity a study intends to estimate. A narrow interval can coexist with uncertainty about selection, missing outcomes, measurement procedures, or analytical choices. The registry does not report the number of participants with a nonmissing primary measurement separately from the posted group sizes, and does not explain any difference between enrollment and endpoint group counts. It also does not report an adjusted estimate or an analysis accounting for baseline measurements.

The interval is not a clinical-importance interval. The registry does not provide a threshold for a meaningful difference in pulse wave velocity. Statistical compatibility with a nonzero contrast does not establish that the difference has a particular clinical consequence. Interpretation also depends on whether the group comparison is unbiased and whether the endpoint and analysis were chosen in advance, details not reported in the registry record.

The standard deviations of 0.3 and 0.2 describe within-group spread, whereas the confidence interval describes uncertainty around the difference in group means. These quantities answer different questions. The reported precision is conditional on the posted summaries and the simple unadjusted method; a different analysis using participant-level data or accounting for design features could produce a different interval. Such an analysis is not reported in the registry record.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning figures are participants per arm, not total events. They are illustrations calculated from the observed effect, not a report of how the trial’s original enrollment target was chosen. The registry’s stated planning assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect to detect is set as the stated fraction of the observed effect. The original trial sample-size assumptions and justification are not reported in the registry record.

The 80% power column gives the estimated participants per arm under those assumptions for a hypothetical study to have an 80% chance of detecting the specified effect if that effect were the true one. The 90% power column gives the corresponding estimate for a 90% chance. These are prospective planning quantities under a model, not evidence that the completed trial had a particular probability of finding a result. This is not observed power.

Rows that plan for a smaller fraction of the observed effect generally require more participants, because smaller group differences are harder to distinguish from random variation. For example, the pressure wave reflection planning figures rise across the rows as the targeted effect is reduced. The listed values are mathematical outputs of the stated simplified assumptions and should not be interpreted as practical enrollment recommendations. Some displayed estimates are very small, reflecting the large observed effects and low posted variability relative to the group differences. Real-world planning would need to account for the intended analysis, likely variability, missing outcomes, feasibility, and clinically meaningful effects; those considerations are not detailed in the registry record.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = -2.200; pooled standard deviation σ = 0.257.
2. n = 2 × (1.96 + 0.842)² × 0.257² / -2.200² = 0.2, rounded up to 1 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- -2.2                      # observed difference in means
sigma <- 0.256944367837214                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(3546270)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 1 (80% power), 1 (90% power)
 75% of observed effect: n per arm = 1 (80% power), 1 (90% power)
 50% of observed effect: n per arm = 1 (80% power), 2 (90% power)
power.t.test: 1.7 
Simulated power at n = 1 per arm: NA (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary outcome and five secondary outcomes, but does not report a statistical analysis plan, an endpoint hierarchy, or a method for addressing multiple comparisons. Multiplicity matters because examining several outcomes can increase the chance of at least one apparently strong result under a set of null hypotheses. This is a general statistical concern; it does not establish that any particular posted result is false. The secondary p-values are unadjusted, so they should be interpreted as individual comparisons rather than as results that account for all outcomes assessed.

Six outcome measures are listed, while numerical secondary group results are posted for three outcomes. Results for diastolic blood pressure and cardiorespiratory endurance are not reported in the registry record. The record does not explain whether these outcomes were measured but not entered, were unavailable, or were omitted for another reason. It also does not report whether the set of posted results represents all prespecified outcomes. Selective reporting therefore cannot be assessed from the available registry information.

The registry does not report participant flow after enrollment, the number with missing measurements, reasons for missingness, or a missing-data method. The endpoint group sizes are 52 for swimming and 48 for control, but the record does not say whether those numbers represent everyone randomized, everyone measured, or the analysis population for each outcome. It does not report whether participants were analyzed according to randomized assignment, whether any participants were excluded, or whether a per-protocol analysis was conducted.

Analysis populations and missing-data decisions can affect the interpretation of randomized comparisons. General approaches include analyzing participants according to assignment and conducting sensitivity analyses under different assumptions about missing outcomes. Whether those or other methods were used is not reported in the registry record. Interim analyses and stopping rules are also not reported. These gaps limit evaluation of multiplicity, attrition, and the extent to which the posted comparisons correspond to a prespecified analysis.

15. 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 zero serious adverse events among 52 participants at risk in the swimming group and zero among 48 at risk in the control group. It also reports zero other adverse events in each group, with the same respective at-risk counts, and zero deaths in both groups. These are the posted event counts for the record.

Zero reported events means that no events in those categories were entered for the listed groups; it does not demonstrate that no unrecorded events occurred or that the intervention is free of risk. The registry does not report event definitions, the period over which events were collected, how actively events were solicited, or whether event reporting was complete for all randomized participants. The record also does not list serious adverse event terms.

Safety interpretation depends on the size of the groups, the duration of observation, and the completeness of event capture. The posted figures describe the registry’s recorded counts, not a comprehensive safety evaluation or a comparison designed to detect rare events. They should be read alongside the missing detail about monitoring and reporting rather than as evidence of absence of risk.

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

The registry’s posted primary endpoint results show a lower mean pulse wave velocity in the swimming group than in the control group at 20 weeks. The recalculated unadjusted mean difference is -2.2 m/s, with a confidence interval from -2.299 to -2.101 and p < 0.001. This is a comparison of group means at the endpoint. It is not a measure of the mean change within individuals because baseline values are not posted with these results.

The results do not establish how durable any group difference might be after the 20-week measurement. Longer follow-up results are not reported in the registry record. Nor do the results establish that the same comparison would apply to other populations, such as people of different ages, sex, or hypertension status. The registry describes elderly women with stage 2 hypertension, and its findings should be understood within that population and study context.

A statistically precise difference does not automatically indicate a clinically important difference. The registry does not state a threshold for meaningful change in pulse wave velocity or report how participants experienced the intervention. No conclusions about individual benefit, treatment decisions, or medical care follow from the posted summary statistics alone. This is a statistical interpretation, not medical advice.

The secondary results point in a broadly consistent direction for the posted cardiovascular and strength outcomes, but two listed secondary outcomes lack numerical results. Unadjusted comparisons across multiple outcomes carry more uncertainty about confirmatory status than a prespecified primary comparison. The registry does not report whether these outcomes were adjusted for multiplicity or selected according to a prespecified hierarchy.

Important design and analysis details are also absent, including masking procedures, allocation concealment, missing-data handling, and the trial’s own statistical model. The recalculated comparisons are simple unadjusted estimates from posted summaries. They characterize the recorded endpoint data, but they cannot substitute for a complete trial report that documents participant flow, measurement procedures, analysis populations, and prespecified methods.

17. Why This Trial Matters Statistically

This trial illustrates the distinction between a clear descriptive contrast and a fully documented analysis. The primary endpoint has group means, standard deviations, a recalculated mean difference, a confidence interval, and an unadjusted p-value. Those statistics make the endpoint comparison interpretable on its original scale. At the same time, the registry does not report the trial’s own analysis methods, so the recalculated estimate cannot be assumed to represent an adjusted or otherwise prespecified model.

It also illustrates why precision is only one part of evidence assessment. The primary confidence interval is narrow, but precision does not answer questions about missing measurements, participant exclusions, masking, outcome selection, or clinical importance. Those aspects require methods and reporting details that are not present in the registry record. Readers need to distinguish uncertainty reflected in a statistical interval from uncertainty caused by incomplete documentation.

The secondary results add context but also raise familiar issues in interpretation. Several outcomes are listed, only some have numerical results, and the posted secondary p-values are unadjusted. A coherent direction across related measures may be informative descriptively, yet it does not remove concerns about multiplicity or unavailable outcomes. A transparent analysis plan and complete results are important for determining which findings were intended to be confirmatory.

Finally, the sample-size illustrations show why planning calculations should not be mistaken for the trial’s original design justification. The planning outputs are based on observed effects and simplified assumptions; the original sample-size rationale is not reported. Planning for plausible, clinically meaningful effects and expected variability is generally more informative than relying on unusually large observed effects from a completed trial. This is a general lesson about study planning, not a claim about the investigators’ intentions.

18. 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 registry record gives limited information for evaluating how the trial was conducted and analyzed. Although it identifies randomization and single masking, it does not describe the allocation sequence, concealment, who was masked, or how masking was maintained. These omissions make it difficult to assess protections against selection and measurement bias.

The swimming intervention description is incomplete after the first 5 weeks. It says that intensity and duration changed as fitness and skill improved, but does not give the remaining schedule. The record also does not state how adherence was measured, whether participants followed the program, or whether contamination between groups was assessed. The control condition included laboratory visits and recreational activities, but the level of attention or other behavior outside those activities is not documented.

Baseline outcome values are not posted with the endpoint summaries. The registry does not report participant flow, reasons for any missing measurements, or whether the group counts represent all randomized participants for each outcome. Consequently, it is not possible to assess attrition or determine how missing data were handled. The trial’s analysis population, covariate adjustment, and statistical model are also not reported.

Only three of the five listed secondary outcomes have numerical group results. The record does not explain the absence of numerical results for diastolic blood pressure and cardiorespiratory endurance. There is no reported multiplicity strategy or outcome hierarchy, and no reported clinical-importance threshold. These limitations are specific to the information entered in the registry; they do not establish that the procedures or analyses were absent from other trial documents.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: The Effects of Swimming on Elderly Women With Stage-2 Hypertension — NCT03546270.
• Registry record last updated 2020-11-18; status last verified 2020-10.
• Results first posted 2019-08-05.
• 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.

22. Record Summary

NCT03546270 is a completed, randomized, single-masked, parallel-group trial sponsored by Pusan National University. It enrolled 100 participants and compared a 20-week swimming program with a non-exercising control among elderly women with stage 2 hypertension.

The primary endpoint was arterial stiffness measured by pulse wave velocity at 20 weeks. The posted means were 7.8 m/s for swimming and 10.0 m/s for control. The recalculated unadjusted mean difference was -2.2 m/s, with a confidence interval from -2.299 to -2.101 and p < 0.001.

Numerical results are posted for three secondary outcomes, while two listed secondary outcomes lack numerical results in the registry record. The record reports zero serious adverse events, zero other adverse events, and zero deaths in both groups. The trial’s own statistical analysis, missing-data procedures, and original sample-size justification are not reported in the registry record.