Benefits of Physical Exercise in Schizophrenia: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Benefits of Physical Exercise in Schizophrenia (NCT02716584), a randomized na study. The primary outcome is VO2max.

2. Clinical Question

3. Trial Design

The registry record describes a randomized, single-masked, parallel-group trial of physical exercise and stretching exercise. The trial is listed as completed, with an enrollment of 53. The record lists schizophrenia as the condition and identifies the VA Office of Research and Development as sponsor. The phase is recorded as not applicable.

Physical exercise consisted of brisk walking; stretching exercise consisted of non-aerobic, non-Yoga stretching. The active comparator is relevant to the interpretation: the observed contrast describes the difference between these two activities, rather than the difference between an activity and no intervention. Details about how random allocation was generated or concealed are not reported in the registry record. The meaning of single masking, including who was masked, is also not reported in the registry record.

The registry lists a start date of 2016-09-01 and a primary completion date of 2018-07-12. The primary outcome was VO2max change from baseline to a 12-week endpoint assessment. The posted primary arm summaries include 27 for physical exercise and 13 for stretching exercise. Those outcome-specific records do not account for every figure associated with enrollment or safety reporting, and the record does not explain the relationship among these different counts. They should therefore be read as the counts attached to their respective posted results, not as a complete accounting of participant flow.

The registry describes the primary endpoint as a continuous measure summarized by means and standard deviations. It also lists secondary outcomes concerning social cognition, BDNF, and positive and negative symptom subscales from the BPRS. Information about the original sample-size justification, the planned analysis population, and the handling of incomplete observations is 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

Reasons for not completing this period:

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 VO2max, measured over Change from baseline to 12-week endpoint assessment.

The primary endpoint is change in VO2max from baseline to the 12-week endpoint assessment. VO2max is described as a measure of aerobic capacity. The registry says it is derived using a regression formula based on age, weight, sex, and the time required to complete a one-mile walk. Because the value is estimated from a regression equation, the record states that it has no absolute minimum or maximum; higher scores represent better aerobic capacity.

Assessing change compares each group’s endpoint with its baseline rather than describing only an endpoint value. The trial’s primary comparison then asks how the mean change differed between the physical exercise and stretching groups. This makes the endpoint relevant to the trial’s stated focus on physical exercise and aerobic capacity. It does not directly measure social integration, cognition, or affect; those topics are represented in the stated rationale and in separate secondary outcomes.

As a continuous outcome, VO2max can be described by a group mean and standard deviation. The mean conveys the average direction and magnitude of change in the posted group, while the standard deviation describes variation among individual changes. The registry’s endpoint description gives the intended meaning of the measure, but does not report a clinically important threshold for interpreting a particular change. The endpoint result should therefore be interpreted as a statistical comparison of mean changes, not as a direct measure of broader social or clinical benefit.

7. Results Posted in the Registry

• Stretching Exercise: mean 0.20 versus 4.00 on control; difference -3.80 (95% CI -7.20 to -0.40), standardized effect d = -0.83; z-test p = 0.028.

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.

Composite Score From Social Cognition Battery

• 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:
  • Stretching Exercise: mean -0.17 versus 0.06 on control; difference -0.23 (95% CI -0.54 to 0.08), standardized effect d = -0.50; z-test p = 0.144.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Stretching Exercise and the control. The interval gives the range of effects that remain compatible with the data.

BDNF Value

• 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:
  • Stretching Exercise: mean -7.31 versus -1.04 on control; difference -6.27 (95% CI -11.93 to -0.61), standardized effect d = -0.69; z-test p = 0.030.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically lower for Stretching Exercise than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Positive Symptom Subscale Score From the BPRS

• 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:
  • Stretching Exercise: mean -1.20 versus -1.20 on control; difference 0.00 (95% CI -1.88 to 1.88), standardized effect d = 0.00; z-test p = 1.000.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Stretching Exercise and the control. The interval gives the range of effects that remain compatible with the data.

The posted secondary outcomes cover social cognition, BDNF, and positive and negative BPRS symptom subscales. Across these measures, the results do not form a uniformly precise pattern of between-group differences. Some posted contrasts have intervals that include zero, while others do not in simple recalculations; the sponsor’s corresponding analyses do not always have the same apparent inferential signal. The full outcome-specific values and methods should be interpreted individually rather than compressed into a single claim about all secondary outcomes.

These outcomes relate to the broader rationale concerning cognition and affect, whereas the primary endpoint measures aerobic capacity. They can therefore add context about other domains but do not directly confirm or negate the primary result. A difference in a secondary measure does not establish a corresponding change in social integration, and the registry does not report a direct primary social-integration endpoint among the outcomes described in the available record.

Unadjusted secondary results generally carry less weight than a prespecified primary result because multiple outcomes create more opportunities for apparently notable findings by chance. Statistical methods can account for this multiplicity, but the registry record does not report whether such an adjustment was planned or applied. The record also does not report a hierarchy or confirmatory status for the secondary analyses. This makes it difficult to distinguish exploratory signals from results intended for formal confirmatory interpretation.

The secondary findings are most appropriately treated as complementary and potentially hypothesis-generating. Their interpretation is constrained by the absence of reported multiplicity procedures, analysis populations, and detailed model specifications. They should not be used to make a broad treatment conclusion or to overrule the primary endpoint’s own reported analysis.

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

• Composite Score From Social Cognition Battery
• BDNF Value
• Positive Symptom Subscale Score From the BPRS
• Negative Symptom Subscale Score From the BPRS

9. Statistical Interpretation

10. Statistical Methods Explained

What does the mean difference describe?

The primary outcome is continuous, so a natural descriptive summary is the mean change in each group. The unadjusted mean difference compares those group means. In the posted comparison, the contrast is expressed as stretching relative to physical exercise: the estimate is -3.8. A negative value therefore indicates a lower average change in stretching than in physical exercise. This direction depends on the order of the groups in the contrast; it does not mean that the physical exercise group had a negative mean change. Its posted mean change is 4.0, while the stretching group’s is 0.2.

A mean difference retains the original outcome scale, ml.kg-1.min-1. It can be read in the measure’s units, unlike a standardized effect size. The recalculation is unadjusted because it uses the posted summary statistics and does not incorporate the covariates or model structure of the sponsor’s ANCOVA. It is useful as a transparent comparison of group summaries, but it is not a replacement for the trial’s own reported analysis.

What do standard deviations and standardized effects add?

A standard deviation describes how dispersed individual changes are around a group mean. For the primary outcome, the posted standard deviations are 4.0 for physical exercise and 5.6 for stretching exercise. Variation matters because a mean difference should be interpreted alongside how much individual outcomes vary. A group can have a particular average change while individual changes within that group remain quite variable.

A standardized effect expresses a difference relative to a pooled measure of variability. The recalculated standardized effect, d, is -0.832 for stretching relative to physical exercise. Standardization can help compare effects measured on different scales, but it removes the original units and does not itself show clinical importance. It also depends on the variability used to standardize the contrast. The sponsor’s reported ANCOVA effect size is 0.41; it is a model-based result and should not be assumed to use the same calculation or direction convention as the recalculated d.

How should a confidence interval be read?

A confidence interval expresses uncertainty around an estimate under the method used to calculate it. For the unadjusted primary mean difference, the 95% interval runs from -7.198 to -0.403. It describes a range of values compatible with the posted data and calculation; it is not a range containing a known fixed proportion of individual participants’ outcomes. A narrower interval indicates greater precision than a wider interval for the same kind of estimate. The registry does not report a confidence interval for its ANCOVA effect size.

The interval for the recalculated mean difference excludes zero. Zero represents no difference in group mean changes under this contrast. This is consistent with the unadjusted p-value of 0.028. A p-value describes how unusual the observed data, or data more extreme, would be under a specified null hypothesis and model assumptions. It does not give the probability that the null hypothesis is true, and it does not quantify the clinical value of the difference.

Why distinguish adjusted and unadjusted analyses?

The sponsor reports an ANCOVA analysis. In general, analysis of covariance compares groups while accounting for specified covariates, which can alter an estimate or its precision compared with a simple unadjusted comparison. The covariates, model specification, assumptions, and analysis population for this ANCOVA are not reported in the registry record. Accordingly, the reported effect size of 0.41 and p = 0.02 can be described as the sponsor’s result, but not independently reconstructed from the posted means and standard deviations.

The recalculated mean difference and its interval are straightforward summaries based on the posted group data. They do not adjust for baseline values or other variables. The sponsor-reported result is the more appropriate description of the trial’s own inferential analysis; the unadjusted recalculation helps readers understand the raw group contrast. Differences between them need not indicate an error because the analyses may estimate the contrast differently.

Why can over-dispersion matter in other settings?

For continuous outcomes summarized by means and standard deviations, variability is already visible through the standard deviations. More generally, some statistical models assume that variability follows a specified pattern. Over-dispersion means that the observed variation is greater than the model expects. If a model does not account for that extra variation, its uncertainty estimates can be too small and its inferences too confident. This is a general statistical consideration, not a reported feature of this trial; the registry does not identify an over-dispersion assessment for the primary endpoint.

For this comparison, readers should focus on the endpoint scale, the group means and standard deviations, the unadjusted interval, and the sponsor’s separate ANCOVA result. Neither a standardized effect, a p-value, nor a planning illustration resolves uncertainty about the model details or the clinical meaning of the observed difference.

11. Confidence Intervals and Precision

The unadjusted primary mean difference is -3.8, with a 95% confidence interval from -7.198 to -0.403. The interval is entirely below zero for the contrast of stretching relative to physical exercise. This indicates that, under the recalculation’s assumptions, the posted data are compatible with a range of negative mean differences rather than a single exact value. The width of the interval is a reminder that the point estimate has uncertainty.

Precision and statistical significance are related but are not the same as clinical importance. An interval that excludes zero indicates that the no-difference value is not within this interval, but does not establish whether every value in the interval would matter clinically. The registry does not report a threshold for a clinically important difference in VO2max, so the clinical meaning of the range cannot be determined from the record alone.

The interval applies to the simple unadjusted recalculation, not to the sponsor’s ANCOVA result. The sponsor reports an effect size of 0.41 and p = 0.02, but no confidence limits for that estimate. Without an interval, the precision of the reported adjusted effect cannot be assessed directly from the registry record. The adjusted and unadjusted results answer related but not necessarily identical statistical questions.

Standard deviations of 4.0 and 5.6 describe variation in change within the two posted outcome groups; they are not confidence intervals for the mean difference. The endpoint arm records list 27 and 13 observations, respectively. These counts are relevant to the posted comparison, but the registry record does not explain participant flow or the treatment of missing outcome observations. Thus, precision should be understood in relation to the reported summaries and the limits of the 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 computed from the observed effect, rather than the trial’s original design assumptions. The 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 the stated fraction of the observed effect. The original design assumptions and sample-size justification are not reported in the registry record.

For 80% power, the planning figure indicates the participants per arm needed under those assumptions for an 80% chance of detecting the specified effect if that effect were the true one. The 90% power column applies the same idea with a higher target chance of detection. These are planning concepts, not guarantees that a future study will detect an effect: the result depends on the assumptions, the true effect, and the analysis.

The rows consider planning for 100%, 75%, and 50% of the observed effect. Smaller effects require more participants because a smaller separation between group means is harder to distinguish from random variation. For example, the primary-outcome illustration lists 23 participants per arm for 80% power and 31 for 90% power when planning for 100% of the observed effect. For 50% of the observed effect, the corresponding figures are 91 and 122 participants per arm.

These calculations are not observed power. They do not describe the probability that the completed trial detected its effect, nor do they explain why the original enrollment was selected. The trial’s own design assumptions, including whether its planning used the same effect or methods, are not reported in the registry record. The figures are best used to understand how assumptions about effect size and power influence future planning, not as a retrospective verdict on the trial.

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 = -3.800; pooled standard deviation σ = 4.566.
2. n = 2 × (1.96 + 0.842)² × 4.566² / -3.800² = 22.7, rounded up to 23 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 <- -3.8                      # observed difference in means
sigma <- 4.56623765432653                     # 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(2716584)
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 = 23 (80% power), 31 (90% power)
 75% of observed effect: n per arm = 41 (80% power), 54 (90% power)
 50% of observed effect: n per arm = 91 (80% power), 122 (90% power)
power.t.test: 23.7 
Simulated power at n = 23 per arm: 0.790 (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. Analyses Reported by the Sponsor

The registry reports the sponsor’s primary analysis as an ANCOVA, with an effect size of 0.41 and p = 0.02. The sponsor’s analysis is the trial’s reported inferential result and takes precedence over the simple unadjusted recalculation when describing the analysis conducted by the sponsor. The registry does not provide a confidence interval for this effect size or enough model detail to reproduce the analysis.

The recalculation uses the posted means and standard deviations to estimate an unadjusted mean difference of -3.8, with a 95% confidence interval from -7.198 to -0.403 and p = 0.028. Its contrast is stretching relative to physical exercise. This helps interpret the raw group summaries but does not account for any adjustments in the sponsor’s ANCOVA. The numerical effect-size values should not be directly equated: the record does not specify the sponsor’s effect-size definition, and the recalculation’s standardized d is a separate quantity.

The difference between the reported p-values does not by itself indicate a contradiction. An adjusted model and an unadjusted calculation can differ in the quantities they estimate and in how they use the available data. The record does not supply the ANCOVA covariates, missing-data approach, or analysis population, so the reasons for the difference cannot be determined. The recalculation is therefore contextual, while the sponsor’s own analysis remains the primary account of the trial’s stated analysis.

15. Multiplicity, Missing Data and Analysis Populations

The registry lists multiple outcome measures and analyses, including a primary endpoint and secondary outcomes. When several outcomes or statistical tests are examined, the chance of at least one apparently unusual result can increase. Multiplicity procedures, such as adjustment of significance thresholds or a prespecified testing hierarchy, can help control that issue. Whether such procedures were planned or used is not reported in the registry record.

The primary result should therefore be distinguished from the secondary results. The primary endpoint has a sponsor-reported ANCOVA result, while secondary outcomes include several separate domains. The registry does not state which secondary analyses were confirmatory, whether they were exploratory, or how their p-values should be interpreted across the family of outcomes. Unadjusted secondary p-values should be read cautiously in that context.

Information about missing observations and the analysis population is also not reported in the registry record. The posted primary outcome counts are 27 for physical exercise and 13 for stretching exercise, while safety reporting uses risk sets of 35 and 18. The record does not explain why these counts differ, whether endpoint data were unavailable for some participants, or what methods were used to address missing data. No assumptions about the reasons for missingness or the approach to analysis can be made from these counts alone.

The registry identifies an ANCOVA for the sponsor’s analysis but does not report the covariates, model details, or population included. It also does not report whether analyses followed intention-to-treat principles, used a per-protocol population, or applied another approach. These omissions limit independent assessment of the analysis and the robustness of its conclusions. They do not establish that any particular method was or was not used; they mean those details are not reported in the registry record.

16. 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’s safety figures report zero serious adverse events and zero deaths in the physical exercise group, with 35 at risk, and zero serious adverse events and zero deaths in the stretching exercise group, with 18 at risk. The record also reports zero other adverse events in each group’s listed risk set. These are counts as recorded for the reported safety categories and risk sets.

Zero reported events means no events were recorded in those categories for the listed groups in the registry entry. It does not prove that the interventions have no safety risks, nor does it establish that all possible adverse effects were assessed or captured. The safety risk-set counts differ from the primary endpoint counts, and the registry does not explain that difference. The adverse-event figures should not be combined with the outcome-specific counts or interpreted as a complete participant-flow account.

The registry does not list serious adverse-event terms. The duration and completeness of safety surveillance, the method of collecting adverse events, and the criteria used to classify them are not reported in the registry record. These limitations matter when interpreting zero counts: they describe what the record reports, not a guarantee about events outside the recorded categories or observation period.

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

The primary result describes a difference in average change in aerobic capacity between two behavioral activities over the trial’s 12-week endpoint period. The posted group means are 4.0 for physical exercise and 0.2 for stretching exercise. The unadjusted mean difference is -3.8 for stretching relative to physical exercise, with a 95% confidence interval from -7.198 to -0.403. The sponsor’s ANCOVA analysis reports an effect size of 0.41 and p = 0.02.

These figures do not establish the size of a clinically important benefit. The record does not provide a threshold for meaningful change in VO2max, and the adjusted sponsor estimate has no reported confidence interval. Nor does a statistical result on aerobic capacity establish effects on social integration, cognition, affect, or outcomes beyond the endpoint period. The secondary measures provide separate information, but multiplicity and analysis details are not reported.

The comparison was against stretching exercise, not against no activity. Thus, the estimate describes the contrast between the two trial arms as reported, not the absolute effect of physical exercise in isolation. The population, eligibility criteria, and analysis population are not detailed enough in the available registry record to establish how widely the findings apply.

The record reports zero serious adverse events and deaths in the listed safety groups, but those counts do not prove an absence of risk. Overall, the findings are best read as a registry-reported statistical comparison with specified limitations in precision, clinical interpretation, missing-data reporting, and analysis detail. They do not warrant a general treatment recommendation or a claim beyond the outcomes and follow-up described.

18. Why This Trial Matters Statistically

This trial illustrates why a clinical result should be read through several statistical lenses. The group means communicate the direction of the observed average changes, while the mean difference puts the between-group contrast on the endpoint’s original scale. The standard deviations show that individual outcomes vary around those averages. A confidence interval then conveys uncertainty around the unadjusted contrast rather than reducing the result to a single p-value.

It also demonstrates the importance of separating an unadjusted recalculation from a sponsor’s model-based analysis. The former is transparent from the posted summaries; the latter is the trial’s reported analysis but cannot be fully assessed without its model details and confidence interval. These are related results, but they should not be treated as interchangeable or used to imply that one reproduces the other.

The active comparator, secondary outcomes, and planning illustrations each affect interpretation. Stretching exercise provides a meaningful study comparison, but the result is not a contrast with no activity. Secondary outcomes broaden the questions being considered, while unreported multiplicity handling makes their statistical signals less definitive. Planning illustrations show how required sample sizes depend on the assumed effect and desired power, but they do not explain the trial’s original design or measure its observed power.

Finally, the registry record shows how missing reporting details constrain statistical assessment. Counts differ across outcome and safety entries, and the record does not describe participant flow, missing-data methods, or analysis populations. Recognizing those limits helps keep a numerical result aligned with what it actually estimates.

19. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

Several limitations specific to this trial affect interpretation. The endpoint records list 27 observations in physical exercise and 13 in stretching exercise, while the safety risk sets are 35 and 18. The registry does not explain these differences or provide a participant-flow account. Consequently, the reasons for the outcome counts, and the extent or handling of missing outcome data, are not reported in the registry record.

The sponsor’s ANCOVA result is reported as an effect size of 0.41 with p = 0.02, but the registry gives no confidence interval and does not describe the model covariates or analysis population. The adjusted estimate’s precision and robustness therefore cannot be independently evaluated from the registry record. The unadjusted recalculation is based on group summaries and should not be mistaken for that model.

The record does not report the original sample-size justification, planned effect size, or original design assumptions. The planning illustrations use the observed effect and stated assumptions, and cannot reveal the basis for enrollment. The record also does not report multiplicity handling for the listed outcomes and analyses, limiting the strength of secondary inferences.

Further details are absent about eligibility criteria, randomization procedures, allocation concealment, who was masked, and the methods for collecting safety information. The record provides no clinically important threshold for VO2max change. These omissions do not show that procedures were inadequate; they limit what can be concluded from the registry information. The 12-week endpoint also limits interpretation to the reported follow-up and measure, without establishing longer-term outcomes.

20. Related Tutorials

21. Related Statistical Calculators

22. Sources

• ClinicalTrials.gov: Benefits of Physical Exercise in Schizophrenia — NCT02716584.
• Registry record last updated 2019-09-19; status last verified 2019-08.
• Results first posted 2019-09-19.
• 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.

23. Record Summary

NCT02716584, titled “Benefits of Physical Exercise in Schizophrenia,” is a completed randomized, single-masked, parallel-group trial sponsored by the VA Office of Research and Development. It compared brisk walking with non-aerobic, non-Yoga stretching exercise. The registry lists enrollment of 53 and a primary endpoint of change in VO2max from baseline to the 12-week endpoint assessment.

The posted mean changes were 4.0 for physical exercise and 0.2 for stretching exercise. The unadjusted mean difference for stretching relative to physical exercise was -3.8, with a 95% confidence interval from -7.198 to -0.403. The sponsor’s ANCOVA analysis reported an effect size of 0.41 and p = 0.02. The registry also lists secondary outcomes concerning social cognition, BDNF, and BPRS symptom subscales.

Interpretation is limited by absent reporting of the original sample-size rationale, multiplicity handling, missing-data methods, analysis populations, and details of the sponsor’s model. The registry reports zero serious adverse events and deaths in the listed safety groups, but does not describe safety surveillance methods.