This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Exercise-induced Hypoalgesia After Comparative Forms of Exercise (NCT01883895), a na na study. The primary outcome is Change in Pain Intensity Ratings (0-100 Pain Scale).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01883895 |
| Phase | NA |
| Condition | Pain |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 34 |
| Arms in the primary outcome | n/a |
| Lead sponsor | University of Wisconsin, Madison |
| Results posted | Yes |
2. Clinical Question
Population
The study concerns healthy adults. The primary outcome description specifies participants completing both exercise sessions and the control session. The registry record lists an enrollment of 34, but does not report how many participants completed every session or contributed to the primary outcome.
Intervention
The exercise conditions are concentric exercise, described as elbow flexion using a dumbbell, and isometric exercise, described as sustained muscle contractions in sets. Pain responses were assessed using a pressure-pain stimulator. The registry record does not report the order in which participants experienced the conditions or other details of how the sessions were scheduled.
Comparator
The control condition involved rest for approximately 10 minutes. The study description raises a question about pain responses after exercise compared with rest, and whether responses differ between the exercise forms. Allocation is recorded as NA, and the record notes that the arms are not a like-for-like control comparison. The design should therefore not be read as a randomized comparison.
Primary question
The primary outcome is change in pain intensity ratings on a 0-100 scale. Ratings were collected before and after pressure stimulation immediately prior to and after exercise, then averaged over 120 seconds. The study description expresses an expectation of increased pain tolerance following exercise, while noting uncertainty about differences between exercise forms. The registry record does not report the outcome estimates needed to determine how the ratings changed or how precisely any differences were estimated.
3. Trial Design
The registry record identifies this as a completed study of exercise-induced hypoalgesia after comparative forms of anaerobic training in healthy adults. The recorded model is single group, allocation is NA, and masking is none. Enrollment is 34. The record gives a start date of 2013-06 and a primary completion date of 2014-05. It lists pain as the condition and the University of Wisconsin, Madison as sponsor.
The described conditions include concentric exercise, isometric exercise, and a control condition involving rest for approximately 10 minutes. Concentric exercise is described as elbow flexion using a dumbbell; isometric exercise is described as sustained muscle contraction. The primary outcome population is defined as participants completing both exercise sessions and the control session. The record does not say how many enrolled participants met that description.
The absence of randomized allocation matters when interpreting differences across conditions. The registry record itself warns that this is not a randomized comparison and that the arms are not a like-for-like control comparison. It does not report the order of conditions, whether all participants experienced the conditions in the same sequence, or how condition effects were separated from other changes over time. Those details are not reported in the registry record, so the design should not be assumed to be a randomized crossover trial.
The primary outcome is continuous: change in pain intensity ratings, summarized as a mean with a 95% confidence interval. A secondary outcome is listed as pain threshold. The record lists two outcome measures and zero analyses. It does not report numerical estimates, confidence intervals, hypothesis tests, or a statistical analysis plan. Consequently, the registry description establishes the intended measurements and broad design, but does not support conclusions about the observed outcome pattern.
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
| Stage | Exercise Treatment |
|---|---|
| STARTED | 34 |
| COMPLETED | 32 |
| NOT COMPLETED | 2 |
Reasons for not completing this period:
| Reason | Exercise Treatment |
|---|---|
| Lost to Follow-up | 2 |
Analysis population for the primary outcome, as defined in the registry: Participants completing both exercise sessions and control session
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: 32 subjects completed study 1 subject enrolled, but did not complete any treatments 1 subject enrolled, but only completed the control session 33 baseline, and 1 drop-out = 34 total
| Characteristic | Unit | Exercise Treatment |
|---|---|---|
| Participants analysed | 33 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 32 |
| Age, Categorical: >=65 years | Participants | 0 |
| Age, Continuous | years | 25.4 (SD 4.2) |
| Sex: Female, Male: Female | Participants | 16 |
| Sex: Female, Male: Male | Participants | 16 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 1 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 31 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 1 |
| Race (NIH/OMB): Asian | Participants | 4 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 2 |
| Race (NIH/OMB): Black or African American | Participants | 1 |
| Race (NIH/OMB): White | Participants | 24 |
| Race (NIH/OMB): More than one race | Participants | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 |
6. Primary Endpoint
The registry lists the primary outcome as Change in Pain Intensity Ratings (0-100 Pain Scale), measured over Average pain rating over 120 seconds.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | 95% Confidence Interval |
| Unit | scores on a scale |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is change in pain intensity ratings on a 0-100 pain scale, where 0 represents no pain and 100 represents the most intense pain imaginable. Participants rated pain after pressure stimulation. Measurements were taken before and after application of the pressure stimulator immediately prior to, and after, exercise. Ratings at 20 second intervals following each administration were averaged over 120 seconds. The stated timeframe is the average pain rating over 120 seconds.
Pain intensity ratings are a continuous measure: they can take values along a scale rather than being limited to a category such as pain present or absent. The registry specifies the mean as the summary measure and a 95% confidence interval as the dispersion measure. A mean can describe the average rating in the analyzed group, while a confidence interval communicates uncertainty around an estimate. Without the actual means and intervals, the size and precision of any change cannot be assessed.
The endpoint is relevant to the stated research question because it records participants’ reported pain intensity after pressure stimulation in relation to exercise and rest conditions. The registry also lists pain threshold as a secondary outcome, but does not provide its numerical results. Neither the primary ratings nor the secondary measure are reported as analyzed results in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record describes a study designed to examine pain ratings following exercise and rest, but it does not report numerical primary outcome results. In particular, it contains no reported mean change, 95% confidence interval, test statistic, or p-value for the primary endpoint. There is therefore no registry-reported estimate from which to describe the direction, magnitude, or precision of a change in pain intensity.
The study description states an expectation that pain tolerance would increase following exercise and uncertainty about whether responses would differ between exercise forms. That statement is a rationale or expectation, not an outcome finding. It cannot establish whether ratings changed, whether any observed changes differed among conditions, or whether the data were consistent with no difference. The secondary outcome, pain threshold, is listed, but its results are also not reported in the registry record.
The registry lists enrollment of 34, but that number should not be treated as the number analyzed. The primary population is participants completing both exercise sessions and the control session; the number meeting that definition is not reported in the registry record. The record lists zero analyses. That means the posted registry information does not provide an inferential analysis to interpret; it is not evidence that the measured responses were unchanged.
Design also limits what a condition contrast would establish. Allocation is recorded as NA, masking as none, and the registry flags that this is not a randomized comparison and that the arms are not a like-for-like control comparison. Any comparison across conditions would need to be interpreted in light of that design rather than treated as a randomized estimate. The record does not report condition order or enough analysis detail to assess how potential order or time effects were handled.
Precision cannot be judged without the reported estimates and their confidence intervals. A confidence interval would indicate a range of values compatible with the data and the analysis assumptions; its width would help show how uncertain the estimate is. No such interval values are reported. Likewise, statistical significance cannot be assessed from the registry record, and statistical significance alone would not establish that a difference is important in practical or clinical terms.
The appropriate reading is therefore descriptive and limited: the record documents a completed study, its intended pain-rating outcome, and the broad conditions, but does not report findings for the outcomes. It neither supports a claim that exercise changed pain ratings nor a claim that exercise had no effect. The numerical evidence needed for either interpretation is not reported in the registry record.
9. Statistical Methods Explained
The primary outcome is a continuous measure summarized by a mean and a 95% confidence interval. In general, a mean combines individual measurements into an average, which can be a useful description of a group when the question concerns average pain intensity. It does not show the full distribution of participants’ responses: participants may have ratings above or below the mean, and the same mean can arise from different patterns of individual values. The registry record does not provide the participant-level ratings or a numerical mean.
In general, a confidence interval expresses statistical uncertainty about an estimated quantity under the assumptions of the analysis. A 95% confidence interval is not a guarantee that a particular interval contains the true value, nor does it indicate that 95% of participants’ measurements fall within its limits. Its width can help readers judge precision: a narrower interval typically indicates a more precise estimate, while a wider interval indicates greater uncertainty. The registry describes the intended confidence-interval summary but does not report its endpoints.
The rating procedure averages measurements collected at 20 second intervals over 120 seconds following pressure stimulation. Averaging repeated ratings can represent the overall response over the stated observation period, rather than focusing on a single moment. It also means the summary depends on the set of ratings contributing to that average. The registry record does not explain how incomplete rating sequences were handled, whether any measurements were excluded, or whether the averaging procedure differed across conditions.
In general, a change score compares a measurement after an intervention or condition with a measurement before it. The exact interpretation depends on how the change is defined and which time points are compared. Here, the primary outcome is titled change in pain intensity ratings, and the description identifies ratings before and after pressure stimulation immediately prior to, and after, exercise. However, the registry record does not provide a numerical definition of the reported change or an analysis model. It would be inappropriate to infer an unreported calculation or assume an adjustment method.
The registry lists allocation as NA, masking as none, and the model as single group. These are design descriptors, not statistical results. Random allocation, when used, can help balance prognostic factors across assigned conditions on average. This record does not describe randomized assignment, and it explicitly cautions that the arms are not a like-for-like control comparison. Without additional design and analysis details, a difference across conditions cannot automatically be attributed to the condition itself.
The record lists a sample-size planning illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The illustration describes detection of a stated fraction of the observed effect. These are planning assumptions, not evidence that the study was designed or analyzed in that way. The calculated planning outputs are not reported in the registry record. As a general principle, planning sample sizes describe hypothetical requirements under chosen assumptions; they are not observed power and do not establish the probability that a study result is correct. A study’s observed data and uncertainty estimates are needed to interpret its findings.
For continuous outcomes, variability is important because it affects how much information a given number of observations carries about a mean or contrast. General statistical methods may also need to account for skewness, outliers, repeated measurements, or differences in variability across conditions. The registry record does not report distributions, variability estimates, diagnostics, or a model for repeated measurements. No claim about these features can be made from the posted record.
Multiplicity arises when several outcomes, time points, or comparisons are examined. In general, making many statistical tests can increase the chance of at least one apparently notable result by chance, depending on the testing strategy. The registry lists two outcome measures, including the primary pain-intensity measure and secondary pain threshold, but does not report a multiplicity approach or results from analyses. There is no basis for stating whether adjustments were used or how multiple endpoints were prioritized in the analysis.
Confidence intervals and p-values answer related but distinct questions. A confidence interval conveys an estimated range and precision, while a p-value, when reported, summarizes compatibility of data with a specified null model under stated assumptions. Neither alone measures clinical importance, and neither can be interpreted without the result, analysis method, and design context. No p-value or confidence interval endpoints are reported for the outcomes in this registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists two outcome measures: change in pain intensity ratings as the primary outcome and pain threshold as a secondary outcome. It does not report a statistical plan specifying which comparisons were primary for inference, whether multiple conditions or time points were tested, or whether any multiplicity adjustment was planned or used. Without that information and without reported analyses, the risk of selective emphasis across outcomes or comparisons cannot be evaluated from the registry record.
Missing-data handling is also not reported in the registry record. The primary outcome population is described as participants completing both exercise sessions and the control session, but the record does not state how many of the 34 enrolled participants completed all sessions or contributed usable ratings. It does not report the amount or pattern of missing measurements, reasons for missingness, or methods for handling incomplete rating sequences. The enrollment figure should not be interpreted as the analysis sample size.
The analysis populations are not described beyond the completer definition for the primary outcome. The record does not report whether participants were analyzed according to an assigned condition, whether any participants were excluded, or how incomplete participation was treated. Since allocation is listed as NA and the record cautions that this is not a randomized comparison, an intention-to-treat framework should not be assumed.
The registry lists zero analyses and does not report numerical outcome estimates. As a result, neither multiplicity procedures nor missing-data assumptions can be checked against reported results. Those omissions limit assessment of the reliability and scope of any possible findings.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Exercise Treatment | 0 | 33 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Exercise Treatment | 0 of 33 |
The serious adverse event listing identifies 33 participants at risk in the Exercise Treatment group and zero participants affected by serious adverse events. The listing for other adverse events also identifies 33 at risk and zero affected. These are the figures recorded for those entries; they should be read as registry counts, not as a complete description of every possible safety outcome.
The deaths field is null, so death information is not reported in the registry record. The record lists no top serious adverse event terms. A zero affected count for the listed group does not establish that every participant completed all study conditions, that no non-serious symptoms occurred beyond the recorded adverse-event entry, or that there is no safety risk. It describes only what is recorded for the specified group and event categories.
The registry does not provide detailed event definitions, a narrative of event monitoring, or additional safety analysis results. It is therefore not possible to assess event timing, severity beyond the serious-event classification, or how the counts relate to specific exercise conditions. The appropriate interpretation is narrow: the posted entry records zero affected among 33 at risk for both the serious and other adverse-event listings, while other safety details are not reported in the registry record.
12. What the Result Does, and Does Not, Mean
The record establishes that a completed study was registered to examine pain ratings following concentric exercise, isometric exercise, and a rest control condition in healthy adults. Its primary outcome is average pain intensity on a 0-100 scale over 120 seconds. These details describe the research question and measurement approach, not the results.
No numerical primary outcome estimates or analyses are reported. Accordingly, the record does not show whether pain ratings increased, decreased, or remained similar after any condition. It also does not show whether the conditions differed from one another, or how precise any estimated differences might be. The stated expectation about increased pain tolerance after exercise is not evidence that this occurred. The secondary outcome, pain threshold, is listed without reported results.
The record also does not establish that the study detected no change. Absence of a reported analysis is not the same as an estimate near zero, and a non-significant result cannot be inferred when no test result is reported. Likewise, the enrollment of 34 cannot be used to infer the sample size used for analysis because the primary population is defined by session completion and the number of completers is not reported.
Design information further narrows interpretation. The registry records no allocation and no masking, and warns that the arms are not a like-for-like control comparison. This makes it especially important not to describe an unreported contrast as a causal effect of one exercise form or of exercise compared with rest. Details about sequence and handling of repeated observations are not reported in the registry record.
In general, a study outcome is most informative when the estimate, its uncertainty, analysis population, and methods are available together. Here, the posted record supplies the intended outcome definition and some design information, but not the numerical evidence needed to judge magnitude, precision, statistical compatibility, or practical importance. No treatment recommendation or conclusion about efficacy follows from these registry entries alone.
13. Why This Trial Matters Statistically
This study raises a statistical question that depends on careful measurement: whether average pain ratings after pressure stimulation vary across exercise and rest conditions. The outcome is a repeated rating summarized across 120 seconds, which makes the definition of the measurement period and the handling of repeated observations relevant to interpretation. The registry describes the measurement schedule, but does not report the resulting estimates or analysis details.
The design description also illustrates why a comparison should not be interpreted from its labels alone. The record calls the model single group, lists allocation as NA, and explicitly cautions that the arms are not a like-for-like control comparison. Statistical interpretation must account for how conditions were experienced and compared. The condition order and the approach to separating condition effects from other changes are not reported in the registry record.
Reporting precision matters as much as reporting an average. A mean without its uncertainty would leave readers unable to judge how stable the estimate might be; the registry specifies a 95% confidence interval but does not report its values. The record lists two outcome measures and zero analyses, leaving no reported inferential results to assess or compare.
For clinical researchers and biostatisticians, the key lesson is that a registered question, an outcome definition, and an enrollment count do not substitute for transparent results. Interpretation requires numerical estimates, uncertainty, analysis populations, and enough methodological detail to understand the comparisons. The missing result reporting prevents evaluation of the study’s statistical findings, regardless of the expectation stated in its description.
14. 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 most important limitation for interpreting this study from the registry record is the absence of numerical outcome results. The record does not report primary or secondary outcome estimates, confidence interval endpoints, p-values, or analysis details. This prevents assessment of direction, magnitude, and precision.
The registry records enrollment of 34, while defining the primary outcome population as participants completing both exercise sessions and the control session. It does not report how many participants completed those sessions or were included in an analysis. Missing ratings, withdrawals, exclusions, and methods for incomplete measurements are not reported in the registry record.
The design is also incompletely described for evaluating condition contrasts. Allocation is NA, masking is none, and the registry flags that the arms are not a like-for-like control comparison. The sequence of exercise and control conditions, the timing between conditions, and the statistical treatment of repeated measurements are not reported. These unknowns preclude confident attribution of any hypothetical difference to a specific condition.
The record lists a primary outcome and pain threshold as a secondary outcome but does not describe how multiple outcomes, comparisons, or time points were handled. A statistical analysis plan, multiplicity approach, and sample-size justification for the original study are not reported in the registry record. The planning illustration is not itself evidence of the design rationale or a reported analysis.
Safety information is limited to adverse-event counts for the listed group; death information is not reported in the registry record. These reporting gaps do not prove that outcomes or events were absent. They limit what can be concluded from this registry entry.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Exercise-induced Hypoalgesia After Comparative Forms of Exercise — NCT01883895.
- Registry record last updated 2017-07-24; status last verified 2017-06.
- Results first posted 2017-07-24.
- 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.
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18. Record Summary
The registry record describes a completed study of exercise-related changes in pain ratings among healthy adults, sponsored by the University of Wisconsin, Madison. Enrollment was 34; the recorded start was 2013-06 and primary completion was 2014-05. The design is listed as single group, with allocation NA and no masking.
The conditions include concentric exercise, isometric exercise, and rest for approximately 10 minutes. The primary outcome is change in pain intensity ratings on a 0-100 scale, averaged over 120 seconds. Pain threshold is listed as a secondary outcome.
The registry lists two outcome measures and zero analyses. Numerical outcome results and analysis methods are not reported in the registry record, so changes, differences, and their precision cannot be evaluated. The adverse-event entry lists zero affected among 33 at risk for serious events and for other events; death information is not reported.