Electrical Muscle Stimulation Versus Resistive Training On Physical Measures, And Fatigue In Hemodialysis Patients: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Electrical Muscle Stimulation Versus Resistive Training On Physical Measures, And Fatigue In Hemodialysis Patients (NCT06079502), a randomized na study. The primary outcome is Assessing the Change in Maximal Strength of Quadriceps and Calf Muscles.

2. Clinical Question

The study also names physical and psychological fatigue and dialysis efficiency as secondary outcomes. The registry describes the trial as comparing intradialytic rehabilitation programs with usual dialysis care, but its posted numerical results include only the primary strength outcome. Results for the secondary outcomes are not reported in the registry record.

The statistical question is therefore narrower than the full study aim: the available group summaries permit comparisons of the reported strength values for each active group against usual-care control. The listed comparisons do not include a direct statistical comparison between electrical stimulation and resistive training. Nor does the record clarify whether the comparison concerns strength at the end of intervention or the amount of change from baseline. That distinction matters when interpreting the reported mean differences.

3. Trial Design

This is a randomized, double-masked, parallel-group trial listed as completed. The registry records an enrollment of 90 and identifies three groups: neuromuscular electrical stimulation, resistive training, and usual-care control. Each group has 30 participants in the posted primary-outcome summaries. The registry lists Cairo University as sponsor and gives the trial dates as starting 2023-10-20 and primary completion 2024-05-30. The phase is listed as NA.

The electrical stimulation group is described as receiving supervised intradialytic neuromuscular electrical stimulation two times per week for 16 weeks with medical treatment. The resistive training group is described as receiving supervised intradialytic resistive training at the same stated frequency and duration with medical treatment. The control group is described as receiving routine maintenance hemodialysis care without the study-specific exercise interventions.

Random allocation can help balance participant characteristics across groups on average, while a parallel design means participants are assigned to one group rather than cycling through interventions. The record labels the trial double-masked, but does not report which people were masked or how masking was maintained. Further details of sequence generation, allocation concealment, intervention adherence, withdrawals, and the populations included in the analyses are not reported in the registry record.

The overall enrollment and the arm counts describe the registered trial and the posted outcome summaries, respectively. The record does not give enough information to determine whether every enrolled participant contributed a primary-outcome measurement or how missing measurements were handled. The study's original sample-size justification and its original statistical analysis plan 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.

Before assignment: no significant pre-assignment events occured

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.

Population: The baseline analysis population included all 90 randomized participants allocated to the three study groups: 30 participants in the intradialytic neuromuscular electrical stimulation group, 30 participants in the intradialytic resistance training group, and 30 participants in the usual-care control group. Baseline assessments were performed before the intervention.

6. Primary Endpoint

The registry lists the primary outcome as Assessing the Change in Maximal Strength of Quadriceps and Calf Muscles, measured over at baseline and after 16 weeks of intervention.

The primary outcome is titled as a change in maximal strength of the quadriceps and calf muscles, with strength measured in kg at baseline and after 16 weeks of intervention. The described assessment uses a handheld traction dynamometer. Participants are seated in a fixed chair with the back supported and the hip and knee at 90°, and are asked to exert their greatest possible force without holding the chair with their arms. The record says that the strength values are the mean of three consecutive measurements obtained by the same investigator, a procedure intended to limit measurement error.

Muscle strength is a continuous measure: it can take a range of numerical values rather than being limited to categories. A dynamometer provides a quantitative way to assess force, while repeated measurements can reduce the influence of variation in any single effort. The quadriceps and calf muscles are both named in the outcome, but the record does not specify whether their results are reported separately, combined, or represented by a particular summary.

There is also an important reporting ambiguity. Although the outcome title refers to change and the timeframe includes baseline and after 16 weeks, the posted results give one mean and standard deviation for each group without identifying the timepoint or stating that the values are changes. Those values therefore cannot be confidently described as baseline-to-follow-up changes based on the registry record alone.

7. Results Posted in the Registry

• Neuromuscular Electrical Stimulation Group: mean 33.83 versus 15.32 on control; difference 18.51 (95% CI 16.66 to 20.36), standardized effect d = 5.05; z-test p = <0.001.
• Resistive Training Group: mean 34.45 versus 15.32 on control; difference 19.13 (95% CI 17.03 to 21.23), standardized effect d = 4.60; z-test p = <0.001.

8. Statistical Interpretation

9. Statistical Methods Explained

Several statistical ideas help interpret continuous outcomes such as muscle strength. The registry reports means and standard deviations for the three groups. A mean describes the group’s average measured value. A standard deviation describes how spread out individual measurements are around that average; it is not the uncertainty in the estimated mean itself. The standard error, by contrast, describes the expected sampling variability of an estimated quantity under a statistical model. A confidence interval uses that uncertainty to convey a range of estimates compatible with the data under the method’s assumptions.

What does a mean difference represent?

A mean difference compares the average values in two groups by subtracting one group mean from the other. In the posted comparisons, usual-care control is the reference group, and the two active intervention groups are each contrasted with it. The reported mean differences are 18.51 kg for neuromuscular electrical stimulation versus usual care and 19.13 kg for resistive training versus usual care. The associated intervals are 16.66 to 20.36 kg and 17.03 to 21.23 kg, respectively.

These estimates describe differences between the group summaries used in the calculation. The outcome title calls the endpoint a change and identifies measurements at baseline and after 16 weeks, but the record does not label the posted means as baseline values, follow-up values, or changes. A difference between follow-up means is not the same quantity as a difference in mean change from baseline. Without a clear label, the statistical contrast can be described, but its clinical time interpretation remains uncertain.

What does a p-value say?

The listed unadjusted p-values are p < 0.001 for each active intervention compared with control. In general, a p-value measures how incompatible the observed data are with a specified null model, under the assumptions of the test. It is not the probability that the null hypothesis is true, and it does not measure the size or importance of a difference. An unadjusted p-value also does not account for testing multiple outcomes or comparisons. The registry record does not report whether an adjustment was planned or used.

The comparisons and inferential summaries in the statistical display are simple, unadjusted recalculations from the posted summary statistics. The record lists no outcome analyses in its analysis count. The discrepancy indicator is false, so there is no recorded disagreement that would make a sponsor analysis take precedence. Still, recalculations from summary values do not supply missing information about the endpoint definition, participant-level data, or analysis population.

Why does the confidence interval matter?

A confidence interval conveys the precision of an estimate as well as its direction. A narrower interval indicates less sampling uncertainty under the calculation’s assumptions than a wider interval. The intervals are centered around positive mean differences and do not include zero. This is consistent with the small unadjusted p-values for the displayed comparisons, since both statistics are based on the same underlying contrast and related assumptions.

Precision is not the same as freedom from bias. A narrow interval cannot correct an unclear endpoint, systematic measurement differences, loss of participants, or limitations in the study design. The registry record does not provide enough detail to assess all such issues. Also, a confidence interval for a difference in reported means does not by itself establish a difference in change over time when the timepoint represented by those means is unspecified.

Why do the reported effect sizes matter for planning?

The registry-associated planning illustration uses the observed differences as a starting point and considers smaller fractions of those effects. It uses a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The resulting sample sizes are illustrations from those assumptions, not the trial’s own design calculation. In general, planning for a smaller effect requires more participants to achieve the same target power, because a smaller signal is harder to distinguish from random variation.

The observed standardized effects listed for these comparisons are 5.05 and 4.602. Such large estimates can produce very small planning counts when used directly, as reflected by the illustration. Planning calculations based on observed effects should be interpreted cautiously: estimates from a particular trial can be imprecise or unusually large, and a planning illustration does not establish that a future trial could reliably detect that effect. The registry's original sample-size justification is not reported in the registry record.

What can the three-arm structure answer?

The posted contrasts address each intervention against usual care. They do not directly test the difference between the electrical stimulation and resistive training groups. Similar-looking group means or overlapping confidence intervals for separate control comparisons do not substitute for that direct test. A direct active-treatment contrast would estimate the difference between those two groups and quantify its uncertainty. That estimate is not reported in the registry record.

Finally, multiple outcome measures and comparisons raise questions about multiplicity, missing data, and analysis populations. A multiplicity strategy can control the chance of false-positive findings when several hypotheses are tested. Missing-data methods and analysis-population definitions explain which participants contribute and how incomplete measurements are treated. The record lists four outcome measures, two posted secondary outcomes, and no reported analyses. The statistical plan for these issues is not reported in the registry record, so the displayed unadjusted contrasts should not be read as a complete account of the trial’s planned analysis.

10. Confidence Intervals and Precision

The mean difference for neuromuscular electrical stimulation versus usual-care control is 18.51 kg, with a 95% confidence interval from 16.66 to 20.36 kg. For resistive training versus usual-care control, the mean difference is 19.13 kg, with a 95% confidence interval from 17.03 to 21.23 kg. Each interval lies above zero and is paired with an unadjusted p-value of p < 0.001.

In general, a 95% confidence interval describes the uncertainty around an estimate using a procedure that, over repeated samples under its assumptions, would capture the target value in 95% of intervals. It does not mean that there is a 95% probability that the particular interval contains the true value. The intervals convey that the calculated differences are estimated with relatively limited sampling uncertainty, conditional on the summaries and assumptions used.

The standard deviations reported for the groups are 3.93 kg, 4.81 kg, and 3.38 kg. These describe variation among measurements within each group, not uncertainty around the difference itself. The estimates and intervals are recalculations based on posted summary statistics rather than participant-level analyses reported in the registry.

Interpretation of precision remains constrained by the outcome ambiguity. The record does not identify whether each mean refers to baseline, the 16-week assessment, or change from baseline. Confidence intervals can quantify uncertainty about the calculated contrast but cannot resolve what quantity the contrast represents. The registry also does not report details needed to assess missing measurements or the analysis population.

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 sample-size figures are planning illustrations, not a reconstruction of the trial’s original design assumptions. They are computed using 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. These figures are participants per arm, not total events. The trial’s own sample-size justification is not reported in the registry record.

The column for 80% power gives the number of participants per arm used in the planning illustration to provide an 80% chance of detecting the assumed effect under the listed statistical assumptions, if that effect is real. The 90% power column uses a higher target chance of detection under the same general framework. Neither column describes the chance that the observed trial result is correct, and these figures are not observed power.

For both active-versus-control comparisons, planning for 100% of the observed effect gives 1 participant per arm for 80% power and 1 participant per arm for 90% power. Planning for 75% of the observed effect gives 2 participants per arm for each power target. Planning for 50% of the observed effect gives 3 participants per arm for 80% power and 4 participants per arm for 90% power. The small figures reflect use of the very large observed standardized effects, not evidence that similarly small trials would generally be adequate.

Smaller effects are harder to distinguish from random variation, so they require more participants for the same target power. The listed progression illustrates that principle. These calculations are conditional illustrations: they depend on the assumed effect, variability, allocation, significance level, and approximation. They should not be treated as a recommendation for a future study or as evidence about the adequacy of this trial’s enrollment.

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 = 18.510; pooled standard deviation σ = 3.665.
2. n = 2 × (1.96 + 0.842)² × 3.665² / 18.510² = 0.6, 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 <- 18.51                      # observed difference in means
sigma <- 3.66533081726602                     # 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(6079502)
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 = 2 (80% power), 2 (90% power)
 50% of observed effect: n per arm = 3 (80% power), 4 (90% power)
power.t.test: 2.1 
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.

13. Multiplicity, Missing Data and Analysis Populations

The registry lists four outcome measures, including the primary strength outcome and two named secondary outcomes: change in physical and psychological fatigue and change in dialysis efficiency. The posted results described in the record include the primary strength summaries, while results for the secondary outcomes are not reported in the registry record. The record’s analysis count is zero. It does not supply a full analysis plan or explain which planned tests were performed.

Multiplicity arises when several outcomes, timepoints, groups, or contrasts are tested. In general, testing more hypotheses without adjustment can increase the chance of at least one apparently positive result arising by chance. Possible approaches include defining one primary comparison in advance or adjusting inference across a family of tests. The registry record does not report whether any such strategy was specified or used. The p-values listed for the active groups versus control are unadjusted, so they do not account for other outcomes or comparisons.

The displayed contrasts compare each active group with usual care. No direct inferential comparison between neuromuscular electrical stimulation and resistive training is reported. Whether that comparison was planned, and how it would fit into a multiplicity strategy, is not reported in the registry record.

Missing-data handling and analysis populations also affect interpretation. The record does not say whether analyses followed an intention-to-treat approach, which participants were included in each analysis, how many measurements were missing, or how missing observations were handled. It lists 30 participants in each group’s posted strength summary, but that does not establish that all randomized participants contributed data or that no data were missing. The original statistical analysis plan and the trial’s original sample-size assumptions are not reported in the registry record.

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 5% reporting threshold.

The serious adverse event figures list 30 participants at risk in each group: neuromuscular electrical stimulation, resistive training, and usual-care control. The number affected by serious adverse events is 0 in each group, and the reported number of deaths is also 0 in each group. The figures for other adverse events likewise list 30 at risk and 0 affected in each group.

These are counts as recorded, not estimates that an event is impossible or that the groups have identical safety profiles. A zero count in a group means no events of that category were recorded among the participants listed at risk in the registry entry. It does not rule out events that were not captured, events occurring outside the reporting period, or differences too uncommon to appear in a trial of this size.

The registry does not provide additional detail on adverse-event definitions, collection procedures, severity grading beyond the serious-event category, or the duration of safety follow-up. It lists no top serious-event terms. The absence of reported events should therefore be read as a feature of the posted record, not as a general conclusion about safety.

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

The posted strength summaries show higher mean values in both active intervention groups than in usual-care control. The corresponding unadjusted mean differences are 18.51 kg for neuromuscular electrical stimulation and 19.13 kg for resistive training, with confidence intervals that lie above zero and p-values of p < 0.001. These statistics describe the contrasts calculated from the group summaries available in the registry record.

They do not establish how much strength changed from baseline, because the record does not clearly identify the reported means as baseline measurements, 16-week measurements, or change scores. The outcome is titled as a change and names both baseline and the post-intervention timeframe, but the numeric result lacks that detail. The values therefore cannot be safely described as intervention-related improvements over time based on the record alone.

The results also do not show whether electrical stimulation differs from resistive training. Each is compared with usual care, and the record does not report a direct active-group contrast. Nor do the posted figures answer the study’s broader questions about fatigue or dialysis efficiency, for which results are not reported in the registry record.

Statistical significance and effect size are different ideas. The small unadjusted p-values indicate incompatibility with a no-difference model under the calculation’s assumptions; they do not establish clinical importance, confirm the endpoint’s interpretation, or remove uncertainty about the design and analysis. The confidence intervals describe precision around the calculated mean differences, not all sources of uncertainty.

Accordingly, the registry supports a narrow description: the recorded group means and recalculated comparisons show substantial contrasts in the reported strength values between each active group and usual care. The record’s endpoint labeling, missing analysis details, and lack of secondary outcome results limit broader conclusions.

16. Why This Trial Matters Statistically

This trial is statistically notable because it has three parallel groups and reports a continuous strength measure, allowing the registry to present contrasts for two active programs against a usual-care comparator. The same structure also makes clear that separate comparisons with control do not answer whether the active programs differ from one another. That distinction is useful when interpreting trials with multiple intervention arms.

The outcome description illustrates why precise endpoint reporting matters. A label referring to change over time should be accompanied by a clear statement of whether results represent follow-up values, change scores, or a model that accounts for baseline. Here, the posted means are not clearly assigned to one of those interpretations. Even narrow confidence intervals cannot resolve that ambiguity.

The record also shows why p-values should be considered alongside effect estimates, confidence intervals, and analysis details. The reported unadjusted p-values are small, while the registry does not describe adjustment for multiple outcomes or comparisons, missing-data handling, or analysis populations. A statistical result is easier to evaluate when these choices are explicitly documented.

Finally, the sample-size illustration is based on the observed effect, and its small participant counts reflect the size of that effect under its stated assumptions. Such illustrations can demonstrate how assumed effect size influences planning, but they are not substitutes for a prospectively justified design. The trial’s own sample-size rationale is not reported in the registry record.

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 principal limitation in interpreting the primary result is that the registry outcome is titled as a change in strength measured at baseline and after 16 weeks, yet each group has only one posted mean and standard deviation. The timepoint and meaning of those summaries are not identified. Consequently, the mean differences cannot confidently be described as differences in change from baseline.

The record names both quadriceps and calf strength but does not clarify whether they are analyzed separately or combined into one reported measure. It describes three consecutive dynamometer measurements and a common investigator, but does not give further information about assessor masking or measurement reliability. Although the trial is labeled double-masked, which people were masked and how are not reported in the registry record.

The posted comparisons are active intervention versus usual-care control. A direct comparison between neuromuscular electrical stimulation and resistive training is not reported. Results for the named secondary outcomes of fatigue and dialysis efficiency are also not reported in the registry record. This limits the available account of the trial’s broader aims.

Additional limitations include the absence of reported details on missing data, analysis populations, multiplicity handling, adherence, and the original sample-size justification. The registry lists 30 participants per group in the outcome summaries, but does not clarify whether these are all randomized participants or how incomplete measurements were addressed. The unadjusted recalculations use posted summary statistics and cannot replace a fuller participant-level analysis.

18. Related Tutorials

19. Related Statistical Calculators

20. Sources

• ClinicalTrials.gov: Electrical Muscle Stimulation Versus Resistive Training On Physical Measures, And Fatigue In Hemodialysis Patients — NCT06079502.
• Registry record last updated 2026-11-02; status last verified 2026-08.
• Results first posted 2026-11-02.
• 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

The registry record identifies NCT06079502 as a completed, randomized, double-masked, parallel-group trial sponsored by Cairo University. It lists 90 participants and compares intradialytic neuromuscular electrical stimulation, intradialytic resistive training, and usual-care hemodialysis. Each group has 30 participants in the posted primary strength summaries.

The primary outcome is maximal quadriceps and calf muscle strength in kg, with a stated timeframe of baseline and after 16 weeks. Posted group means are 33.83 kg, 34.45 kg, and 15.32 kg for electrical stimulation, resistive training, and usual care, respectively. The registry does not clearly state which timepoint or summary those means represent. Unadjusted recalculated mean differences versus usual care are 18.51 kg and 19.13 kg, each with p < 0.001.

Fatigue and dialysis efficiency are listed as secondary outcomes, but their results are not reported in the registry record. Serious adverse events, other adverse events, and deaths are recorded as zero in each group. Important details of the analysis plan, missing-data handling, and original sample-size justification are not reported in the registry record.