Mechanistic Drivers of Acute PAPE Responsiveness: Muscle Architecture, Contractile Kinetics, and Excitability in a Randomized Controlled Trial: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Mechanistic Drivers of Acute PAPE Responsiveness: Muscle Architecture, Contractile Kinetics, and Excitability in a Randomized Controlled Trial (NCT06982937), a randomized na study. The primary outcome is Jump Height 4 Minute.

2. Clinical Question

The registry summary describes baseline testing and repeat tests immediately after warm-up and at 4, 6, 8, 10, and 12 minutes. It also describes estimating muscle fiber mix from the first muscle-speed test. Those planned measures provide context for the broader scientific question, but the registry record contains no posted secondary results. The primary result alone therefore cannot establish how jump height changed from baseline over time, whether an individual’s response lasted, or whether estimated fiber mix explained variation in response.

3. Trial Design

NCT06982937 is listed as a completed randomized controlled study with a parallel-group model and triple masking. The registry records an enrollment of 44 and lists the study start as 2025-02-02 and primary completion as 2025-06-25. Its phase is recorded as NA. The sponsor is The Jerzy Kukuczka Academy of Physical Education in Katowice.

The two groups received different warm-up activities: a high-intensity half-squat set or treadmill running. The registry describes the treadmill activity as five minutes at a comfortable pace. The brief summary says participants were randomly assigned and that they would not know which warm-up they received until the end. The registry does not report further details about the randomization procedure or which study roles were masked.

The primary endpoint is jump height at 4 minutes post-intervention. The posted results give a group mean and standard deviation for each arm, with 22 participants in each. The trial summary describes additional measurements of jump height, muscle speed and stiffness, muscle size and fiber angle, and nerve signals at baseline and after the warm-up, including repeated post-intervention time points. It also describes an assessment of whether estimated muscle fiber mix relates to the size and duration of jump changes. These are descriptions of the planned study questions; no secondary results are posted in the registry record.

The record lists 58 outcome measures, but no analyses and no posted secondary outcomes. It does not report the original sample-size justification, detailed statistical analysis plan, analysis populations, handling of missing observations, or whether any interim analyses were planned. Those omissions limit what can be concluded about how the investigators intended to analyze the full set of measurements or how the posted primary comparison fits into a broader analysis strategy.

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 Jump Height 4 Minute, measured over 4 minutes post-intervention.

The primary endpoint is mean jump height, measured in centimetres at 4 minutes post-intervention. Jump height is a direct performance measure relevant to the study’s question about acute post-activation performance enhancement. A comparison at a specified time point can describe whether the group averages differ at that moment after the assigned warm-up.

The endpoint is a group-level mean, not a measure of how every participant responded. The registry reports a mean and standard deviation for each group. The mean describes the group’s average jump height; the standard deviation describes the spread of individual measurements around that average. These quantities answer different questions: the mean locates the group average, while the standard deviation conveys variability among participants.

The result at 4 minutes does not by itself quantify change from baseline, establish the time course of any response, or explain why participants might differ. Although the study summary describes repeated tests and several muscle and nerve measures, the registry record posts no secondary results for those outcomes. Thus, the primary endpoint is useful for a focused comparison between the two warm-up groups at the specified time, while the proposed mechanistic and duration questions remain unanswered by the posted primary result alone.

7. Results Posted in the Registry

• Treadmill Running: mean 47.41 versus 45.34 on control; difference 2.07 (95% CI -1.01 to 5.15), standardized effect d = 0.40; z-test p = 0.187.

8. Statistical Interpretation

9. Statistical Methods Explained

The primary result is a comparison of two group means for a continuous outcome. Jump height is recorded in centimetres, and the registry identifies the summary parameter as a mean with standard deviation. A mean difference expresses the separation between group averages in the outcome’s original units. In this record, the estimated difference is 2.07 cm, with treadmill running as the comparison arm relative to high-intensity half-squat. Keeping the direction explicit matters: reversing the order of the groups would reverse the sign of the difference, without changing the underlying observations.

What does the standard deviation describe?

A standard deviation describes how dispersed individual observations are around their group mean. It is not the uncertainty in the estimated mean difference. The reported standard deviations are 5.28 cm for the half-squat group and 5.13 cm for the treadmill group. A group can have substantial variation among participants even when its mean is estimated with some precision, and the uncertainty in a comparison depends on both the observed variation and the number of observations. The registry also reports a pooled standard deviation of 5.206 for the comparison, but it does not explain the calculation procedure or say that this quantity was used in a prespecified analysis.

How should the mean difference be read?

The mean difference is an effect estimate in centimetres. It describes the observed separation of the group averages at the endpoint, not an individual participant’s change and not a comparison of each participant’s response to baseline. The reported estimate is 2.07 cm. This is a summary of the trial observations; it does not, by itself, establish why the averages differ or whether a difference is important for a practical performance question. The registry record does not report a threshold for a meaningful difference.

What does the confidence interval add?

A confidence interval conveys statistical uncertainty around an estimated effect. In general, a wider interval indicates less precision, while a narrower interval indicates greater precision under the assumptions of the method used. The reported 95% confidence interval for the mean difference extends from -1.006 to 5.146 cm. Because it includes zero, the observed data do not rule out no average difference at the usual two-sided 0.05 significance level. The interval also allows for effects in either direction. A confidence interval is not a guarantee that the true value lies within its limits, and it does not capture every possible source of bias or design limitation.

What does the p-value say?

The reported p-value is unadjusted and equals 0.187. In general, a p-value describes how compatible the observed data are with a specified null hypothesis under the assumptions of the statistical test. It is not the probability that the null hypothesis is true, nor a measure of the size or practical importance of an effect. The record does not identify the exact test or fully describe its assumptions, so the p-value should be interpreted as the posted unadjusted result rather than as evidence of a particular analysis method.

Why does over-dispersion matter in general?

For continuous measurements, variability can be larger than an analysis anticipates. In general, over-dispersion means that observations vary more than the model or working assumptions allow. If variability is underestimated, standard errors can be too small and confidence intervals can be too narrow, making evidence appear more precise than it is. This is a general statistical concern, not a finding about this trial: the registry does not report a diagnostic assessment of over-dispersion. The posted standard deviations show variation in the observed endpoint, but do not alone establish whether a model assumption was met.

What is not established about the analysis?

The registry reports no analyses beyond the primary comparison and does not provide the original statistical analysis plan. It does not state whether the primary analysis was adjusted for baseline jump height or other participant characteristics, how the repeated measurements were analyzed, or how any missing measurements were handled. It also does not identify the analysis population or report details of the randomization sequence. Those details cannot be inferred from the group means, confidence interval, or p-value. The primary result can be described as posted, while the exact analysis choices and their relationship to the protocol are not reported in the registry record.

10. Confidence Intervals and Precision

The estimate of the mean difference in jump height at 4 minutes post-intervention is 2.07 cm, with a 95% confidence interval from -1.006 to 5.146 cm. This interval is the main guide to the precision of the comparison. It spans zero, so it is compatible with no average difference, but it also permits differences favoring either group. The estimate alone is not enough to distinguish among those possibilities.

In general, a confidence interval summarizes uncertainty associated with an estimate under the statistical method used. It does not mean that every value within the interval is equally likely, and it does not account automatically for sources of uncertainty that the analysis did not model. The registry does not describe the method used to construct this interval, so its technical assumptions cannot be checked from the record.

The group means are based on 22 participants in each arm. The reported standard deviations are 5.28 cm for the half-squat arm and 5.13 cm for the treadmill arm. These describe observed spread among participants, whereas the confidence interval concerns uncertainty in the group comparison. Both are useful, but they are not interchangeable. The interval’s breadth cautions against reading the point estimate as a precise account of the difference.

The unadjusted p-value is 0.187. It is consistent with the interval’s inclusion of zero, but it should not replace consideration of the estimated difference and its range. The registry record does not report a threshold for a practically meaningful change in jump height. Therefore, the statistical interval cannot by itself determine practical importance, and the posted result does not settle whether smaller or larger effects would matter for the study’s intended performance question.

11. 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 illustration is for participants per arm, not total events. It uses a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The effect to detect is set to a stated fraction of the observed effect. These are planning assumptions for an illustration based on the observed result, not reported assumptions from the trial’s original design. The original sample-size justification is not reported in the registry record.

For 100% of the observed effect, the illustration lists 100 participants per arm for 80% power and 133 participants per arm for 90% power. For 75% of the observed effect, it lists 177 participants per arm for 80% power and 237 participants per arm for 90% power. For 50% of the observed effect, it lists 398 participants per arm for 80% power and 532 participants per arm for 90% power.

In general, 80% power means that a study designed under the stated assumptions would have an 80% chance of detecting the target effect using the specified statistical criterion, if that effect were the true effect and the assumptions held. The 90% column expresses the corresponding higher chance of detecting that target effect. A smaller effect is harder to distinguish from random variation, so the illustration requires more participants per arm when the target is a smaller fraction of the observed effect.

These are planning illustrations, not observed power. They should not be read as the number actually enrolled, nor as evidence that the completed trial had a particular probability of finding a difference. The trial enrolled 44 participants, and the primary endpoint result includes 22 in each group. The illustration also relies on the observed effect as its starting point, which is uncertain; it does not establish what sample size would be appropriate for a future study with a separately justified target effect.

12. 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 = 2.070; pooled standard deviation σ = 5.206.
2. n = 2 × (1.96 + 0.842)² × 5.206² / 2.070² = 99.3, rounded up to 100 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 <- 2.06999999999999                      # observed difference in means
sigma <- 5.20554031777682                     # 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(6982937)
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 = 100 (80% power), 133 (90% power)
 75% of observed effect: n per arm = 177 (80% power), 237 (90% power)
 50% of observed effect: n per arm = 398 (80% power), 532 (90% power)
power.t.test: 100.2 
Simulated power at n = 100 per arm: 0.795 (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.

13. Multiplicity, Missing Data and Analysis Populations

The registry lists 58 outcome measures and describes repeated assessments of jump height and muscle or nerve characteristics in its study summary. However, it posts no secondary outcome results and reports zero analyses. The only result available for interpretation in this record is the primary comparison of jump height at 4 minutes post-intervention. The many listed measures and time points create a general multiplicity concern: when numerous statistical questions are tested, the chance of at least one apparently unusual result can increase. Whether and how that concern was addressed is not reported in the registry record.

The registry does not report a multiplicity adjustment, a hierarchy of outcome tests, or a prespecified distinction between confirmatory and exploratory analyses. It is therefore not possible to tell whether the primary comparison was intended to stand alone or how it related to the wider set of measures. The posted p-value is explicitly unadjusted, so it should not be treated as an adjusted result across outcomes or time points.

Missing-data handling is also not reported in the registry record. The posted endpoint summaries include 22 participants in each group, but the record does not describe whether all randomized participants contributed measurements, whether any endpoint values were missing, or how incomplete repeated measurements were handled. Equal reported group counts do not establish that there were no missing observations at other time points or on other measures.

The analysis population is not specified. The record does not say whether the primary comparison followed an intention-to-treat approach, included only participants with an observed endpoint, or used another population definition. The original statistical analysis plan and any interim-analysis plan are not reported in the registry record. These omissions mean that the relation between the posted result and the trial’s planned inferential framework cannot be assessed from the registry information alone.

14. 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 event figures for 22 participants at risk in each group. It lists zero serious adverse events affecting participants in the high-intensity half-squat group and zero in the treadmill-running group. It also lists zero other adverse events affecting participants in each group, with 22 at risk in each. Deaths are listed as zero for both groups.

These figures are event counts within the recorded at-risk groups. They do not show that an event could not occur, and they do not establish comparative safety beyond what was observed and entered in the registry. With no reported events in either group, the data do not estimate a difference in event frequency. The record also does not provide detailed event descriptions, follow-up duration for adverse events, or information about how events were collected. Serious adverse event terms are not listed.

The figures should therefore be read narrowly: no serious adverse events, other adverse events, or deaths are recorded for either group in these posted results. They do not support conclusions about uncommon risks or safety in populations beyond the trial participants described in the registry.

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

The primary result describes average jump height at 4 minutes after the assigned warm-up. The posted mean was 45.34 cm for high-intensity half-squat and 47.41 cm for treadmill running. The reported mean difference, treadmill running minus half-squat, was 2.07 cm, with a 95% confidence interval from -1.006 to 5.146 cm and an unadjusted p-value of 0.187. The interval includes zero and allows for effects favoring either group, so the estimate remains uncertain.

This result does not establish that either warm-up caused a change from baseline. Baseline results and a change-from-baseline estimate are not posted for the primary endpoint. It also does not answer whether any change persisted across the subsequent measurement times described in the study summary. No secondary results are posted for muscle size, fiber angle, contractile properties, muscle excitability, or estimated muscle fiber mix. The proposed mechanistic questions therefore remain unresolved in the registry record.

The group mean comparison is not a description of every participant’s response. Individuals may differ, but the registry does not post participant-level data or response distributions. The reported standard deviations indicate observed variability in each group, while the confidence interval represents uncertainty around the comparison. Neither identifies which individual participants responded or why.

The findings should not be treated as proof of equivalence between the warm-ups, since the interval includes potentially meaningful values in both directions and the registry gives no threshold for practical importance. Nor should the difference between sample means be treated as proof that one warm-up has a performance benefit. The record supports a limited statistical description of the primary endpoint for the enrolled groups at the specified time point; broader claims about efficacy, mechanism, duration, or generalizability are not established by these posted results.

16. Why This Trial Matters Statistically

This trial raises a useful statistical distinction between a mechanistic research question and a single endpoint comparison. Its stated aims encompass jumping performance, muscle architecture, contractile kinetics, excitability, and whether muscle-fiber composition relates to response. The posted primary result addresses only the mean jump height comparison at 4 minutes post-intervention. Keeping the scope of the estimate aligned with the scope of the question helps prevent a narrow result from being used to answer unreported mechanistic questions.

The estimate, confidence interval, and p-value illustrate why evidence should be read as a set. The point estimate gives the observed direction and size of the group-average difference in centimetres. The interval shows that substantial uncertainty remains, including values on either side of zero. The p-value is unadjusted and does not measure the probability that a warm-up works or the practical importance of an effect. Together, these statistics describe an uncertain primary comparison rather than a definitive answer about the broader study aims.

The record also highlights the interpretive importance of prespecified analysis details. With 58 listed outcome measures and repeated measurements described in the study summary, readers would need the analysis plan, outcome hierarchy, missing-data approach, and multiplicity strategy to understand how the full set of questions was handled. Those details and secondary results are not reported in the registry record. Their absence does not change the arithmetic of the posted primary comparison, but it constrains interpretation of how that comparison fits into the full research program.

Finally, the planning illustration makes clear that sample-size requirements depend on the target effect and planning assumptions. Its figures are not the trial’s original design justification and do not describe observed power. Separating planning scenarios from trial results is essential when assessing whether an estimate is precise and what future studies might need to resolve.

17. 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 primary endpoint result is limited to jump height at 4 minutes post-intervention. Although the study summary describes baseline and repeated post-warm-up assessments through 12 minutes, no results for baseline change or the other time points are posted. This prevents interpretation of the time course or persistence of any observed group difference.

The registry posts no secondary outcome results despite listing 58 outcome measures. The proposed measures of muscle speed and stiffness, muscle size and fiber angle, nerve signals, and estimated fiber mix therefore cannot be linked to the primary endpoint using the posted results. The number and relationships among the planned measures also make the unreported multiplicity strategy relevant.

The primary comparison includes 22 participants in each arm, but the record does not report the trial’s original sample-size justification or its planned target effect. The sample-size illustration is based on the observed effect and stated planning assumptions, so it cannot establish whether the completed trial was designed to detect a particular scientifically meaningful difference.

Important analysis details are absent: the exact test used, the method for constructing the confidence interval, whether covariate adjustment was planned, the analysis population, handling of missing data, and any interim-analysis plan are not reported in the registry record. The record also does not give a threshold for a practically meaningful jump-height difference. These omissions limit assessment of the analysis assumptions, robustness, and practical interpretation.

The study description concerns healthy football players ages 18-21 who train regularly and meet the health rules. The posted comparison therefore does not, by itself, establish how results would apply to other populations or settings. The registry’s adverse-event entries are also limited to the recorded counts and do not provide detailed event definitions or follow-up information.

18. Related Tutorials

19. Related Statistical Calculators

20. Sources

• ClinicalTrials.gov: Mechanistic Drivers of Acute PAPE Responsiveness: Muscle Architecture, Contractile Kinetics, and Excitability in a Randomized Controlled Trial — NCT06982937.
• Registry record last updated 2025-12-16; status last verified 2025-11.
• Results first posted 2025-12-16.
• 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.

21. Record Summary

NCT06982937 is a completed randomized, triple-masked, parallel-group study sponsored by The Jerzy Kukuczka Academy of Physical Education in Katowice. The registry lists enrollment of 44, a start date of 2025-02-02, and primary completion on 2025-06-25. The two arms compared a high-intensity half-squat warm-up with treadmill running.

The primary endpoint was mean jump height in centimetres at 4 minutes post-intervention. The posted means were 45.34 cm for half-squat and 47.41 cm for treadmill running, with a reported mean difference of 2.07 cm, a 95% confidence interval from -1.006 to 5.146 cm, and an unadjusted p-value of 0.187. The interval includes zero, leaving uncertainty about the direction and size of the group difference.

No secondary results or additional analyses are posted. The registry record does not report the original sample-size justification, detailed analysis plan, missing-data approach, multiplicity strategy, or analysis population. Adverse-event entries list zero serious events, other events, and deaths in both groups.