Taekwondo Training and Postmenopausal Women With Stage-2 Hypertension: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Taekwondo Training and Postmenopausal Women With Stage-2 Hypertension (NCT03544307), a randomized na study. The primary outcome is Blood Epinephrine Levels.

2. Clinical Question

The registry describes a broader set of questions about catecholamines, arterial stiffness, blood pressure, resting heart rate, and muscular strength. The posted primary endpoint is specifically blood epinephrine levels, so it should be distinguished from those other measures. The reported contrast compares the group means at the 12-week timeframe; it is not a comparison of change from baseline because baseline values and a change-score analysis are not reported in the registry record.

Random allocation makes the group comparison relevant to the assigned training program, but the record does not describe allocation concealment, adherence, or the analysis population. The comparator was asked not to exercise, rather than assigned another activity. The result therefore describes the difference between these two trial conditions as recorded, not the isolated effect of any one component of the training program.

3. Trial Design

This was a randomized, parallel-group trial with no masking. The registry lists enrollment of 20 and status as completed. The listed study dates are 2017-05-01 for the start and 2018-03-01 for primary completion. The phase is recorded as NA. Kosin University is listed as the sponsor.

Participants were assigned to Taekwondo training or sedentary control. Training was scheduled for 60 minutes per day, 3 days per week, for 12 weeks. Intensity began at 30-40% of heart rate reserve and was gradually increased to 50-60% over 12 weeks. The control group was asked not to exercise. The registry does not report details such as how the random sequence was generated, whether allocation was concealed, or how adherence to the assigned conditions was assessed.

The primary outcome was blood epinephrine levels at 12 weeks, reported as a mean and standard deviation in pg/mL. Arterial stiffness, systolic and diastolic blood pressure, hand grip strength, and leg strength are listed as secondary outcomes. Numeric results are available for arterial stiffness, systolic blood pressure, and hand grip strength; numeric results for diastolic blood pressure and leg strength are not reported in the registry record.

The outcome groups each have a reported sample size of 10. The record does not state whether all randomized participants were included in every analysis, whether any participants discontinued, or how missing measurements were handled. It also does not provide an analysis plan or identify a particular analysis population. Those omissions limit assessment of how the posted group summaries were produced and whether the analysis followed a prespecified plan.

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 Blood Epinephrine Levels, measured over 12-weeks.

The primary endpoint is blood epinephrine level, measured in pg/mL at 12 weeks. Epinephrine is one of the blood catecholamines named in the trial title and summary. The registry reports the outcome as a continuous measure summarized by a group mean and standard deviation. A mean describes the center of the observed values within a group; the standard deviation describes how dispersed those values are around the mean.

Comparing the means gives a compact description of the average endpoint in the two assigned groups at the stated follow-up. In the posted results, the Taekwondo group mean was 39.3 pg/mL, with a standard deviation of 7.1, and the control group mean was 46.2 pg/mL, with a standard deviation of 4.7. The unadjusted mean difference was -6.9 pg/mL, with a confidence interval from -12.18 to -1.623 and an unadjusted p-value of 0.01.

As a general statistical point, a continuous endpoint can retain information about the range of measured values rather than reducing each participant to a category. The mean difference describes the size and direction of the group contrast in the endpoint's units. It does not, by itself, explain why the group means differ or establish how the values changed from baseline. Baseline epinephrine measurements and a change-from-baseline result are not reported in the registry record.

7. Results Posted in the Registry

• Taekwondo Training: mean 39.30 versus 46.20 on control; difference -6.90 (95% CI -12.18 to -1.62), standardized effect d = -1.15; z-test p = 0.010.

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.

Arterial Stiffness

• 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:
  • Taekwondo Training: mean 7.67 versus 8.48 on control; difference -0.81 (95% CI -1.69 to 0.07), standardized effect d = -0.81; z-test p = 0.070.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Taekwondo Training and the control. The interval gives the range of effects that remain compatible with the data.

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:
  • Taekwondo Training: mean 130.00 versus 142.00 on control; difference -12.00 (95% CI -13.75 to -10.25), standardized effect d = -6.00; z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically lower for Taekwondo Training than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Hand Grip 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:
  • Taekwondo Training: mean 27.00 versus 24.00 on control; difference 3.00 (95% CI -0.10 to 6.10), standardized effect d = 0.85; z-test p = 0.058.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Taekwondo Training and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes cover arterial stiffness, blood pressure, and muscular strength. Across the outcomes with numeric group summaries, the directions are not uniform: arterial stiffness and systolic blood pressure have lower reported means in the training group, while hand grip strength has a higher reported mean. The precision also differs across comparisons, with some confidence intervals including zero and another lying wholly below zero. The posted results for diastolic blood pressure and leg strength are not reported in the registry record.

These outcomes add context to the primary epinephrine comparison because they describe other measures named in the trial's aims and registry listing. They do not directly verify the primary result: each is a different endpoint, with its own measurement scale, variability, and statistical uncertainty. Nor does a pattern across several outcomes establish a single mechanism. The registry record does not report analyses linking changes in epinephrine to changes in stiffness, pressure, or strength.

The secondary comparisons carry less weight because their p-values are unadjusted and the record does not describe a prespecified hierarchy or multiplicity adjustment. When many outcomes are examined, some can appear noteworthy by chance. The record lists five secondary outcome topics, while numerical group results are posted for three. The status of the other listed outcomes and the reason their numerical results are absent are not reported in the registry record. These limitations make the secondary findings useful as descriptive evidence, but not as a substitute for a fully reported confirmatory analysis.

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

• Arterial Stiffness
• Systolic Blood Pressure
• Hand Grip Strength
• Diastolic Blood Pressure
• Leg Strength

9. Statistical Interpretation

10. Statistical Methods Explained

The posted outcomes are continuous measures reported as means and standard deviations. For the primary endpoint, the record gives a mean and standard deviation for each group, then a mean difference comparing Taekwondo training with control. A mean difference is expressed in the original unit of the outcome, which makes its direction and scale interpretable without converting the measure.

What does the mean difference express?

The contrast is defined as the training-group mean minus the control-group mean. A negative value therefore indicates a lower mean in the training group; a positive value indicates a higher mean. For blood epinephrine, the reported contrast is -6.9 pg/mL. This is a difference between the posted group means at 12 weeks, not a percentage difference and not a change from baseline. The record does not report an adjusted estimate, so the posted comparison should be read as unadjusted.

What does the standard deviation tell the reader?

A standard deviation describes the spread of individual observations around a group mean. It is not the uncertainty interval for the mean difference and does not indicate how precisely the contrast is estimated. The primary endpoint standard deviations are 7.1 in the training group and 4.7 in control. General statistical interpretation: the standard deviation concerns variation among observations, whereas a confidence interval for a contrast concerns uncertainty about the estimated group difference.

How should the p-value be understood?

The primary unadjusted p-value is 0.01. In general, a p-value measures how incompatible the observed data, or more extreme data, are with a specified null model, assuming that model and the analysis assumptions hold. It is not the probability that the null hypothesis is true, and it does not measure the size or importance of the group difference. The registry record does not report a full statistical analysis plan, so details such as the exact test, any covariate adjustment, or how analysis choices were selected are not reported in the registry record.

Why does randomization matter, and what does it not settle?

In general, random allocation aims to make treatment assignment independent of participant characteristics, supporting a comparison between assigned groups. It does not guarantee that small groups will be balanced on every characteristic, and it does not remove concerns about missing measurements, adherence, or decisions made after assignment. This registry record identifies the allocation as randomized but does not report the sequence-generation method, allocation concealment, or baseline outcome values. The result therefore remains a comparison of the posted group summaries, with limited detail on the procedures behind them.

Why might a small trial give an uncertain estimate?

With modest group sizes, estimates can be sensitive to the observations of a few participants. A wide confidence interval reflects uncertainty in the estimated contrast; even a narrow interval should be interpreted in light of the design and analysis details. General statistical explanation: sample size, variability, and the size of the underlying contrast all affect precision. The registry outcome groups each report 10 participants, but the record does not state whether every randomized participant contributed data to every endpoint.

The comparison values and confidence intervals are unadjusted calculations based on the posted group summaries. The discrepancy indicator is false, so no disagreement with a sponsor analysis is flagged. The registry record does not list a separate reported analysis. This distinction matters because summary-statistic calculations do not reveal whether a prespecified sponsor analysis used a different model, covariates, or analysis population. In general, where sponsor-reported analyses are available and differ from a recalculation, the sponsor's own analysis takes precedence.

General statistical interpretation also distinguishes statistical uncertainty from clinical importance. A confidence interval can show the range of values compatible with the estimate under its assumptions, but it does not set a threshold for meaningful change. No clinical threshold for epinephrine or other endpoints is reported in the registry record. The values should therefore be interpreted as statistical descriptions of the trial results, not as a standalone judgment about clinical relevance.

11. Confidence Intervals and Precision

The primary mean difference is -6.9 pg/mL, with a confidence interval from -12.18 to -1.623. In general, a confidence interval summarizes uncertainty in an estimate under the model and assumptions used to construct it. The interval is not a range in which individual participants' values are expected to fall; it concerns the underlying group contrast. Its endpoints indicate that the estimate is more precise than a single point estimate alone can convey, while still allowing a range of possible contrasts.

The interval for the primary outcome lies below zero. That aligns with the reported negative mean difference and indicates that the posted estimate favors a lower group mean in the training arm for this endpoint. The unadjusted p-value is 0.01. A p-value and confidence interval are related ways of expressing uncertainty, but neither measures clinical importance. The registry record does not report a threshold for a meaningful difference in blood epinephrine.

Precision varies across the other reported outcomes. The arterial stiffness interval, -1.687 to 0.067 m/s, includes zero. The systolic blood pressure interval, -13.75 to -10.25 mmHg, does not include zero. The hand grip strength interval, -0.099 to 6.099 kg, includes zero. These intervals describe the uncertainty in their respective unadjusted mean differences; they should not be treated as interchangeable because each outcome has its own unit and variability.

General statistical explanation: interval width is influenced by the amount of information in the data and the variability of the outcome. Small group sizes can make estimates sensitive to individual observations. The confidence intervals do not account for uncertainty from unreported design or analysis choices, and the registry record does not report whether any multiplicity adjustment was applied. The intervals should therefore be read as precision summaries for the posted comparisons, not as complete measures of every source of uncertainty.

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 participants and not total events. They are illustrations calculated from the observed effect, rather than the original trial's design justification. The listed assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. Each planning scenario targets the stated fraction of the observed effect: 100%, 75%, or 50%. The trial's own original sample-size assumptions are not reported in the registry record.

The 80% power column gives the illustrative number of participants per arm for a future study designed to have an 80% chance of detecting the stated effect under those assumptions, if that effect and the assumptions are correct. The 90% power column gives the corresponding planning figure for a 90% chance. These are design targets, not guarantees about a future result. Smaller effects generally require more participants to detect with the same power, which is why the planning figures rise when the assumed effect is reduced from the full observed effect to a fraction of it.

For the primary epinephrine comparison, the planning display gives 12 participants per arm for 80% power and 17 per arm for 90% power when planning for 100% of the observed effect. Planning for 75% gives 22 and 29 per arm, respectively; planning for 50% gives 48 and 65 per arm. These figures rely on the effect observed in a small trial and should be treated as illustrations rather than a dependable prediction of the effect in another study. This is not observed power.

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 = -6.900; pooled standard deviation σ = 6.021.
2. n = 2 × (1.96 + 0.842)² × 6.021² / -6.900² = 12.0, rounded up to 12 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 <- -6.90000000000001                      # observed difference in means
sigma <- 6.02079728939615                     # 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(3544307)
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 = 12 (80% power), 17 (90% power)
 75% of observed effect: n per arm = 22 (80% power), 29 (90% power)
 50% of observed effect: n per arm = 48 (80% power), 65 (90% power)
power.t.test: 13 
Simulated power at n = 12 per arm: 0.764 (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 one primary outcome and five secondary outcome topics. Numeric results are posted for the primary epinephrine endpoint and for three secondary measures. The record does not report numerical results for diastolic blood pressure or leg strength. It also does not report a prespecified testing hierarchy, an adjustment for multiple comparisons, or an explanation of how the primary and secondary hypotheses were prioritized.

Multiplicity matters because assessing several outcomes creates multiple opportunities for apparently unusual results. General statistical explanation: without a planned approach to multiple testing, an unadjusted p-value for an individual endpoint does not reflect the fact that other endpoints may also have been tested. The posted secondary p-values should therefore be interpreted cautiously, particularly when the record does not show how the outcomes were selected or whether all analyses were planned in advance.

The registry record does not report an interim-analysis plan, stopping rules, or details of the statistical analysis plan. It does not specify the analysis population, whether the comparison followed an intention-to-treat approach, or how missing outcome data were handled. Baseline group characteristics and baseline endpoint values are also not reported in the outcome information. These omissions prevent assessment of whether groups were comparable at baseline or whether missingness could have influenced the reported summaries.

There are 10 participants reported in each outcome group, but the registry record does not clarify whether these are all randomized participants or whether every participant had a measurement for every endpoint. No assumptions about attrition or imputation can be made from the posted record. The record does not list a separate reported analysis, so the available comparisons should be read as unadjusted descriptions based on the reported group summaries rather than as evidence that a particular prespecified analysis plan was followed.

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 in the Taekwondo group and zero in control. The number at risk for serious adverse events is 10 in each group. It also reports zero other adverse events in each group, with 10 at risk in each. Deaths are recorded as zero in both groups, and no serious adverse event terms are listed.

These figures describe the events recorded in the registry for the trial. A zero count means that no events in that category were reported among the listed group counts; it does not establish that the risk is absent or precisely estimated. The record does not provide detailed event definitions, a description of surveillance, or a safety-analysis timeframe beyond the trial's stated outcome timeframe. It also does not give additional information about event severity apart from the serious versus other categories.

With the reported group sizes, the absence of recorded events should be interpreted as limited safety information rather than as proof that no adverse events could occur. The registry figures do not support comparisons of event risk beyond the reported counts.

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

The posted primary result describes a lower mean blood epinephrine level in the Taekwondo group than in sedentary control at 12 weeks. The estimated mean difference was -6.9 pg/mL, with a confidence interval from -12.18 to -1.623 and an unadjusted p-value of 0.01. These statistics summarize the observed comparison and its uncertainty; they do not by themselves establish a clinical benefit or explain the cause of the difference.

The trial studied postmenopausal women with stage-2 hypertension and compared a specified Taekwondo training program with a sedentary control condition. The result should not automatically be extended to other populations, exercise programs, or follow-up periods. The record does not report outcomes beyond the 12-week timeframe for the posted measures, so persistence after training is not established by these data.

The endpoint is a laboratory measure, and the registry record does not provide a threshold for interpreting a change as clinically important. The result also does not show whether individual participants' levels changed from baseline, because baseline values and change analyses are not reported in the registry record. The posted mean contrast cannot identify which aspects of the intervention might account for the difference.

The secondary results include measures with differing directions and precision. They may inform further study, but their unadjusted nature and incomplete reporting limit how strongly they can support broader claims. The safety record reports no serious or other adverse events, but the small recorded groups and absence of detail about event ascertainment limit conclusions from those counts. Overall, the posted data are best understood as a short-term randomized group comparison with important design and analysis details not reported in the registry record.

17. Why This Trial Matters Statistically

This trial illustrates why estimates, intervals, and design details belong together. The primary mean difference gives the direction and scale of the blood epinephrine comparison, while its confidence interval conveys uncertainty beyond the point estimate. Reading only the p-value would omit both the size of the contrast and the range of values compatible with the estimate.

The record also shows how a randomized design and a small outcome sample can coexist. Randomization is valuable for structuring a comparison, but a small trial can still produce imprecise estimates and cannot ensure balance on every feature. The posted group summaries are informative, but missing details about allocation procedures, baseline values, adherence, missing data, and analysis population make it harder to assess the full strength of the evidence.

The collection of secondary outcomes highlights the importance of distinguishing confirmatory from exploratory evidence. A set of unadjusted comparisons can help describe a pattern, yet without a reported multiplicity strategy or testing hierarchy, individual secondary p-values warrant caution. The planning illustrations likewise demonstrate that sample-size calculations depend on assumptions about the effect worth detecting; smaller target effects require larger planned groups under the listed assumptions.

Finally, safety counts and efficacy-related measurements answer different questions. Zero reported adverse events are useful as a record of what was observed, but do not establish that risks are absent. Statistical interpretation depends not just on numerical results, but also on the completeness of outcome reporting, analysis plans, and follow-up information.

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 enrollment was 20, and the outcome groups each report 10 participants. This is a small evidence base, so the estimated group differences may be sensitive to the values of individual participants. The record does not report whether all randomized participants contributed to each outcome or whether any measurements were missing.

The trial was unmasked. The registry record does not identify who knew the assignments during outcome measurement or analysis, so the potential influence of knowledge of assignment cannot be assessed. It also does not report allocation concealment, the random-sequence method, adherence to the training schedule, or baseline characteristics. These omissions limit evaluation of the conduct and comparability of the groups.

The reported outcome timeframe is 12 weeks. Longer-term outcomes are not reported in the registry record, and the record does not provide baseline endpoint results or change-from-baseline analyses. It is therefore not possible to assess the trajectory of the measures from these posted summaries. The record lists five secondary outcome topics but provides numeric group results for only three; results for diastolic blood pressure and leg strength are not reported in the registry record.

The registry does not report the statistical analysis plan, missing-data approach, analysis population, multiplicity adjustment, or interim-analysis procedures. The unadjusted comparisons consequently have limited context, especially across multiple outcomes. The record also gives no clinical threshold for meaningful change in the primary measure. These limitations do not negate the posted estimates, but they constrain their interpretation and generalizability.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Taekwondo Training and Postmenopausal Women With Stage-2 Hypertension — NCT03544307.
• Registry record last updated 2020-11-10; status last verified 2020-11.
• 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

NCT03544307 is a completed, randomized, parallel-group trial sponsored by Kosin University. It enrolled 20 postmenopausal women with stage-2 hypertension and compared 12 weeks of Taekwondo training with a sedentary control condition. The trial was not masked.

The primary outcome was mean blood epinephrine at 12 weeks. The training group mean was 39.3 pg/mL and the control mean was 46.2 pg/mL; the unadjusted mean difference was -6.9 pg/mL, with a confidence interval from -12.18 to -1.623 and p = 0.01. Secondary results were posted for arterial stiffness, systolic blood pressure, and hand grip strength.

The record does not report several design and analysis details, including the statistical analysis plan, missing-data handling, and analysis population. Secondary results are unadjusted, and numerical results are not reported for every listed secondary outcome.