Immediate and Short-Term Effects of Nature-Based Immersive Virtual Reality During Dry Needling: A Single-Blinded Randomized Controlled Trial

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This paper addresses a timely and clinically relevant question: can nature-based immersive virtual reality reduce pain associated with dry needling? The topic is interesting because dry needling is widely used in musculoskeletal rehabilitation, yet the procedure itself can be painful and may provoke anxiety or fear in some patients. The idea of using immersive VR as a non-pharmacological adjunct is therefore both practical and innovative.

The main strength of the study is its clear clinical rationale. The trial design also has several positive features. The authors used random allocation, allocation concealment, a control group, and blinded outcome assessment.

major concerns:

1. The title and conclusions appear to somewhat overstate the findings.
   The title emphasizes “immediate and short-term hypoalgesic effects.” However, the most consistent finding of the study is a reduction in immediate pain intensity, rather than a clearly sustained short-term hypoalgesic effect.
2. The presentation of effect sizes requires clarification.
   In Table 2, the between-group difference in immediate pain appears to be about 1.4 points, which seems unlikely to correspond to the reported Cohen’s d = 1.75 based on the reported standard deviations. A similar concern applies to the PPT results at 1 hour. The authors should clarify whether the reported effect sizes reflect between-group effects, within-group changes, or change-score differences.
3. The control condition is not sufficiently refined to identify the active therapeutic component. 
   The DN+IVR group received multiple elements, including nature-based scenery, music, guided breathing, visual feedback, immersion, novelty, and distraction. Since the control group received DN alone, the study cannot determine whether the effect was due to immersive VR itself or to other components. Future studies should include active control conditions.
4. The sample characteristics substantially limit the external validity of the findings.
   Participants were healthy young adults with latent myofascial trigger points, not clinical pain patients. The exclusion of individuals with needle phobia also limits applicability to those who may benefit most from VR-assisted dry needling.
5. The mechanistic interpretation exceeds the variables measured in the study.
   The discussion mentions distraction, autonomic modulation, relaxation, and nature-based pain modulation, but the study did not measure anxiety, fear, expectancy, presence, immersion, physiological responses, or neural activity. These explanations should be presented as hypotheses.
6. The primary outcome and primary time point should be more clearly specified.
   Because pain intensity and PPT were assessed at multiple time points, the authors should clearly define the primary outcome and primary assessment time point to reduce the risk of selective emphasis and false-positive findings.
7. The statistical analysis could be strengthened by using a linear mixed-effects model.
   A linear mixed-effects model would better account for time, group, group-by-time interaction, and individual variability than separate ANOVAs and t-tests. Confidence intervals for effect sizes should also be reported, especially given the small sample size.
8. Please ensure consistency in reporting participant sex. In the Results section, the authors use both “males” and “men.” Since sex appears to be the demographic variable reported, it would be preferable to use “male participants” or “participants who were male” consistently throughout the manuscript.

 

Author Response

General comment: This paper addresses a timely and clinically relevant question: can nature-based immersive virtual reality reduce pain associated with dry needling? The topic is interesting because dry needling is widely used in musculoskeletal rehabilitation, yet the procedure itself can be painful and may provoke anxiety or fear in some patients. The idea of using immersive VR as a non-pharmacological adjunct is therefore both practical and innovative.

The main strength of the study is its clear clinical rationale. The trial design also has several positive features. The authors used random allocation, allocation concealment, a control group, and blinded outcome assessment.

Response: We thank the Reviewer 1 for taking the time to review this manuscript  and for the positive and encouraging comments. We appreciate the recognition of the clinical relevance of our study and the interest in the use of immersive virtual reality as an adjunct to reduce pain during dry needling.

We are also grateful for the acknowledgment of the methodological strengths of our trial, including random allocation, allocation concealment, the use of a control group, and blinded outcome assessment.

According to the comments of the Reviewers and Editor, the use of English has been carefully reviewed throughout the manuscript to ensure clarity, coherence, and consistency, and minor typographical errors have been corrected.

 

Comments 1: The title and conclusions appear to somewhat overstate the findings.

The title emphasizes “immediate and short-term hypoalgesic effects.” However, the most consistent finding of the study is a reduction in immediate pain intensity, rather than a clearly sustained short-term hypoalgesic effect.

Response: Thank you very much for your appreciation. However, the title refers to the time points studied, not to the results found. In this case, both immediate and short-term effects (up to 24 hours) on pain have been evaluated. According to the current definition, a hypoalgesic effect is a reduction in evoked or reported pain following an intervention, which can be measured both by evoked stimuli (PPT, for example) and by self-reported scales.

 

Comments 2: The control condition is not sufficiently refined to identify the active therapeutic component.

The DN+IVR group received multiple elements, including nature-based scenery, music, guided breathing, visual feedback, immersion, novelty, and distraction. Since the control group received DN alone, the study cannot determine whether the effect was due to immersive VR itself or to other components. Future studies should include active control conditions.

Response: We appreciate your suggestion. This has been included in the limitations and future studies section of the discussion.

“Since the control group only received the DN intervention, some of the components of the IVR group such as the nature-based IVR environment, music, guided breathing, visual feedback or novelty may significantly influence the differences between groups.”

 “Future studies should include comparator groups such as sham VR, non-immersive nature video or breathing-only control for more rigorous placebo-controlled response”.

 

Comments 3: The sample characteristics substantially limit the external validity of the findings.

Participants were healthy young adults with latent myofascial trigger points, not clinical pain patients. The exclusion of individuals with needle phobia also limits applicability to those who may benefit most from VR-assisted dry needling.

Response 3: Indeed, the characteristics of the sample limit the generalizability of the results to the clinical population, as explained in the limitations. However, given that there is no previous evidence on the use of IVR during DN, we considered it appropriate to first conduct a study in non-clinical subjects, and in a second stage to reproduce the same study (improving some of the limitations) in a healthy population. Pain during DN has been widely reported as the major adverse effect, and may be a precursor to fear of needle based on contemporary models such as the fear-avoidance model. Although our study does not allow us to ascertain the effect on  fear of needle, it may be a first step to explore potential indications for IVR during invasive physiotherapy.

“Despite its relevant contributions, this study has several limitations that should be considered. First, the sample of healthy young participants may limit the extrapolation of the results, particularly in the chronic pain population, myofascial pain syndrome or fear of needle.”

 

Comments 4: The mechanistic interpretation exceeds the variables measured in the study.

The discussion mentions distraction, autonomic modulation, relaxation, and nature-based pain modulation, but the study did not measure anxiety, fear, expectancy, presence, immersion, physiological responses, or neural activity. These explanations should be presented as hypotheses.

Response 4: Thank you very much for your suggestion. We have reviewed the section on mechanisms, rephrasing it in terms of a hypothesis by using the word ‘could’. We have also included a statement explaining that further studies are needed to explore these variables.

“Nevertheless, since this study did not include measures of anxiety, fear or expectancy, future studies should include these variables in order to examine these effects.”

 

Comments 5: The primary outcome and primary time point should be more clearly specified.

Because pain intensity and PPT were assessed at multiple time points, the authors should clearly define the primary outcome and primary assessment time point to reduce the risk of selective emphasis and false-positive findings.

Response 5: We thank the reviewer for this important comment.

We agree that clearly defining the primary outcome and its main assessment time point improves transparency and reduces the risk of selective reporting. In line with this suggestion, we have revised the manuscript to explicitly define pain intensity measured immediately after the intervention as the primary outcome and primary time point, as this directly reflects the main objective of the study, namely the evaluation of the immediate hypoalgesic effect of immersive virtual reality during dry needling.

Pressure pain threshold (PPT), as well as all other follow-up assessments (30 minutes, 1 hour, 6 hours, and 24 hours), are now explicitly described as secondary outcomes and secondary time points, intended to explore the short-term evolution of the intervention effects.

These clarifications have been incorporated into the Outcome Measures and Statistical Analysis sections of the manuscript.

Comments 6: The statistical analysis could be strengthened by using a linear mixed-effects model.

A linear mixed-effects model would better account for time, group, group-by-time interaction, and individual variability than separate ANOVAs and t-tests. Confidence intervals for effect sizes should also be reported, especially given the small sample size.

Response 6: We thank the reviewer for this valuable and constructive suggestion.

Following this recommendation, we have reanalysed the data using linear mixed-effects models (LMMs), which more appropriately account for the repeated-measures design, group effects, time, group × time interactions, and inter-individual variability. Separate models were fitted for pain intensity and pressure pain threshold (PPT), including group, time, and their interaction as fixed effects, and a random intercept for participants.

In addition, and in line with the reviewer’s suggestion, we have now reported regression coefficients (β) with their corresponding 95% confidence intervals (CIs) for all fixed effects. These estimates provide a more informative interpretation of the magnitude and precision of the observed effects, particularly given the relatively small sample size.

The results obtained with the LMM approach were consistent with our initial findings, confirming a significant reduction in immediate post-intervention pain intensity in the DN+IVR group compared to the control group, while no sustained between-group differences were observed at later time points.

The Statistical Analysis and Results sections have been fully revised accordingly.

 

 

Comments 7: Please ensure consistency in reporting participant sex. In the Results section, the authors use both “males” and “men.” Since sex appears to be the demographic variable reported, it would be preferable to use “male participants” or “participants who were male” consistently throughout the manuscript.

Response 7: Thank you for your comment. We have consistently used the term ‘male participants’ to refer to sex.

Reviewer 2 Report

Comments and Suggestions for Authors

This manuscript addresses an interesting and potentially novel topic: the use of immersive virtual reality to reduce pain associated with dry needling. The randomized design, prospective registration, allocation concealment, and blinded outcome assessment are clear strengths.

However, the manuscript requires major revision before it can be considered for publication. There are relevant issues regarding the study aim, timing of the intervention, definition of the primary outcome, statistical reporting, interpretation of the PPT findings, and clinical generalization of the results. In addition, some sections still contain template text or editorial inconsistencies.

 

1. Clarify when the virtual reality intervention was applied

The title and several sections state that IVR was applied “following dry needling”. However, the Methods indicate that the IVR started before needling and ended immediately after the procedure. Therefore, the intervention seems to have been applied during dry needling rather than after dry needling.

This should be corrected throughout the title, abstract, objective, methods, discussion, and conclusion.

A more accurate title could be:

“Immediate and short-term effects of nature-based immersive virtual reality during dry needling: a single-blinded randomized controlled trial”.

2. Clearly define the primary outcome

The manuscript reports pain intensity and pressure pain threshold at several time points, but the primary outcome is not clearly defined.

The authors should specify:

• the primary outcome;
• the secondary outcomes;
• the main time point of interest;
• whether these outcomes were pre-specified in the trial registration;
• whether there were any deviations from the registered protocol.

This is important to avoid selective interpretation of statistically significant findings.

3. Provide a sample size calculation

No sample size calculation is reported. Given the small sample size and the number of repeated comparisons, the study may be underpowered, particularly for PPT outcomes.

The authors should provide an a priori sample size calculation. If no calculation was performed, the study should be presented as exploratory or pilot, and the conclusions should be more cautious.

4. Recheck the statistical analyses, p-values, and effect sizes

There seem to be inconsistencies between the reported means, standard deviations, p-values, and effect sizes.

For example, the immediate between-group difference in pain intensity is 1.4 points, but the reported Cohen’s d = 1.75 appears too large for the presented values. Similarly, the result for PPT at 1 hour is unclear, since it is not evident whether the reported p = 0.011 refers to a between-group difference or a within-group change.

The authors should carefully revise:

• all p-values;
• all effect sizes;
• whether each comparison is within-group or between-group;
• main effects and group × time interactions;
• post hoc analyses;
• confidence intervals.

For this design, the group × time interaction should be central to the interpretation, rather than only within-group changes.

5. Report mean differences with 95% confidence intervals

The manuscript would be improved by reporting between-group mean differences with 95% confidence intervals, especially for:

• immediate pain after dry needling;
• changes in PPT;
• pain intensity at 1 h, 6 h, and 24 h.

This would help readers better understand the precision and clinical relevance of the findings.

6. Revise the interpretation of PPT

The interpretation of pressure pain threshold needs clarification. A reduction in PPT usually indicates increased mechanical sensitivity, not hypoalgesia.

The results appear to support an immediate reduction in self-reported procedural pain, but they do not show a clear and consistent hypoalgesic effect on PPT. This should be reflected in the abstract, discussion, and conclusion.

7. Avoid overgeneralization to clinical populations

The sample consisted of healthy young adults with latent myofascial trigger points. Therefore, the findings cannot be directly generalized to patients with myofascial pain syndrome, chronic pain, anxiety, or needle phobia.

Some statements about clinical implementation, anxiety reduction, fear of needles, healthcare costs, or broader clinical use are too strong because these variables were not measured. These points should be presented as hypotheses for future research.

8. The control group does not control for placebo, attention, or expectancy effects

The experimental condition included several components: immersive VR, nature exposure, music, guided breathing, visual feedback, novelty, and distraction. The control group received dry needling only.

Therefore, the observed effect cannot be attributed specifically to the nature-based IVR environment. It may also be explained by distraction, relaxation, breathing, expectancy, or novelty effects.

This limitation should be discussed more clearly. Future studies should consider comparator groups such as sham VR, non-immersive video, breathing-only control, headset-only control, or neutral VR.

9. Provide more detail on dry needling dosage

The dry needling protocol needs more detail to ensure reproducibility and to confirm that both groups received a comparable stimulus.

The authors should report:

• actual number of needle insertions;
• number of local twitch responses;
• actual duration of needling;
• whether tolerance differed between groups;
• whether IVR allowed greater tolerance and therefore changed the DN dose;
• whether the same physiotherapist treated all participants;
• clinician experience;
• adverse events.

This is relevant because IVR could change pain tolerance and indirectly modify the dry needling stimulus.

10. Improve the description of trigger point identification

The criteria used to identify latent myofascial trigger points should be described more clearly.

The authors should specify:

• diagnostic criteria used;
• whether taut band, hypersensitive spot, referred pain, or local twitch response were required;
• examiner experience;
• whether reliability was assessed;
• side assessed;
• dominance;
• previous exposure to dry needling or VR.

11. Report adverse events

The manuscript should explicitly report whether any adverse events occurred during or after dry needling or IVR, including bleeding, bruising, vasovagal symptoms, dizziness, nausea, cybersickness, post-needling soreness, or discomfort from the headset.

If no adverse events occurred, this should be stated.

12. Align the discussion with the actual results

The discussion should focus on the main supported finding: IVR reduced immediate self-reported pain during/after dry needling.

However, the effect did not clearly persist in the short term, and PPT did not show a consistent pattern. Proposed mechanisms such as autonomic modulation, anxiety reduction, or fear reduction should be discussed more cautiously, since these variables were not directly measured.

Minor comments

1. Remove the template text at the beginning of the Results section.
2. Remove the “Patents” section if it is not applicable.
3. Correct the “Institutional Review Board Statement”, as it currently seems to include funding information.
4. Remove unrelated abbreviations such as MDPI, DOAJ, TLA, and LD.
5. Use “PPT” consistently. In some places, “PTT” appears.
6. Do not use “pressure pain threshold” and “pain tolerance threshold” interchangeably.
7. Revise the abstract for grammar and clarity. For example, “Our results shows” should be “Our results show”.
8. Revise the phrase “no differences between groups were found at certain time series”, as it is unclear.
9. Improve table formatting, especially Table 2.
10. Check consistency between the text, tables, and figures.
11. Use the journal’s required citation style consistently. Some citations appear in author-year format.
12. Check that all cited references are included in the reference list.
13. Consider replacing “muscle spasm” with “local twitch response”, if that is the intended term.
14. Use “participants” rather than “patients”, since the sample consisted of healthy individuals.
15. Make the conclusion more cautious.
16. Check the hyphens on words that shouldn`t be there, for example in the abstract: be-twee

Author Response

General comment: This manuscript addresses an interesting and potentially novel topic: the use of immersive virtual reality to reduce pain associated with dry needling. The randomized design, prospective registration, allocation concealment, and blinded outcome assessment are clear strengths.

However, the manuscript requires major revision before it can be considered for publication. There are relevant issues regarding the study aim, timing of the intervention, definition of the primary outcome, statistical reporting, interpretation of the PPT findings, and clinical generalization of the results. In addition, some sections still contain template text or editorial inconsistencies.

Response: We thank the reviewer for taking the time to review this manuscript  and for the positive evaluation of the novelty and methodological strengths of our study, including the randomized design, prospective registration, allocation concealment, and blinded outcome assessment.

We also appreciate the reviewer’s thorough and constructive feedback. We acknowledge the concerns raised regarding the study aim, timing of the intervention, definition of the primary outcome, statistical reporting, interpretation of the PPT findings, and clinical generalization. In addition, we recognize the need to correct the remaining template text and editorial inconsistencies.

The use of English has been carefully reviewed throughout the manuscript to ensure clarity, coherence, and consistency, and minor typographical errors have been corrected.

All these points have been carefully addressed in the revised manuscript. Detailed responses to each comment are provided below.

 

 

Comments 1: Clarify when the virtual reality intervention was applied

The title and several sections state that IVR was applied “following dry needling”. However, the Methods indicate that the IVR started before needling and ended immediately after the procedure. Therefore, the intervention seems to have been applied during dry needling rather than after dry needling.

This should be corrected throughout the title, abstract, objective, methods, discussion, and conclusion.

A more accurate title could be:

“Immediate and short-term effects of nature-based immersive virtual reality during dry needling: a single-blinded randomized controlled trial”.

Response: Thank you for your suggestion. The title has been revised and changed to “Immediate and short-term effects of nature-based immersive virtual reality during dry needling: a single-blinded randomised controlled trial”.

 

Comments 2: Clearly define the primary outcome

The manuscript reports pain intensity and pressure pain threshold at several time points, but the primary outcome is not clearly defined.

The authors should specify:

the primary outcome;

the secondary outcomes;

the main time point of interest;

whether these outcomes were pre-specified in the trial registration;

whether there were any deviations from the registered protocol.

This is important to avoid selective interpretation of statistically significant findings.

Response 2: We thank the reviewer for this comment.

In response, we have revised the manuscript to clearly and explicitly define the outcomes and their hierarchy, as well as their alignment with the trial registration.

First, the primary outcome has now been clearly defined as pain intensity (NRS) measured immediately after the intervention, as this directly reflects the main objective of the study, namely the evaluation of the immediate hypoalgesic effect of immersive virtual reality during dry needling.

Second, secondary outcomes have been explicitly specified as:

• pressure pain threshold (PPT), and
• pain intensity at follow-up time points (1 hour, 6 hours, and 24 hours),
  which were included to explore the short-term evolution of the intervention effects.

Third, the primary time point of interest has been defined as immediately post-intervention, and this has now been stated a priori in the Outcome Measures and Abstract sections.

Regarding the trial registration, these outcomes and time points were consistent with the objectives and design described in the registered protocol (ClinicalTrials.gov: NCT06448104), which focused on the evaluation of immediate and short-term hypoalgesic effects. No post hoc changes to outcome prioritization were made.

Finally, we confirm that no deviations from the registered protocol occurred in relation to outcome definition or assessment time points.

Comments 3: Provide a sample size calculation

No sample size calculation is reported. Given the small sample size and the number of repeated comparisons, the study may be underpowered, particularly for PPT outcomes.

The authors should provide an a priori sample size calculation. If no calculation was performed, the study should be presented as exploratory or pilot, and the conclusions should be more cautious.

Response: We thank the reviewer for this important comment.

An a priori sample size estimation was performed prior to the study. Given that this was the first study evaluating pain intensity during dry needling using immersive virtual reality as a distractive intervention, a specific effect size for this exact condition was not available. Therefore, the sample size was initially based on previous studies investigating dry needling in similar muscle groups, which typically included approximately 18 participants per group.

Assuming a 10% dropout rate, a target sample size of 20 participants per group was established, resulting in a total of 40 participants.

Additionally, evidence from the virtual reality literature indicates large effects on pain reduction. A meta-analysis reported a mean effect size of approximately d = 0.90 for virtual reality interventions on pain outcomes, supporting that the current sample size is sufficient to detect clinically meaningful differences in the primary outcome.

This information has now been incorporated into the Methods section.

Comments 4: Recheck the statistical analyses, p-values, and effect sizes

There seem to be inconsistencies between the reported means, standard deviations, p-values, and effect sizes.

For example, the immediate between-group difference in pain intensity is 1.4 points, but the reported Cohen’s d = 1.75 appears too large for the presented values. Similarly, the result for PPT at 1 hour is unclear, since it is not evident whether the reported p = 0.011 refers to a between-group difference or a within-group change.

The authors should carefully revise:

all p-values;

all effect sizes;

whether each comparison is within-group or between-group;

main effects and group × time interactions;

post hoc analyses;

confidence intervals.

For this design, the group × time interaction should be central to the interpretation, rather than only within-group changes.

Response: We thank the reviewer for this very careful and insightful assessment of the statistical analysis.

We acknowledge that the previous version of the manuscript may have led to inconsistencies and potential misinterpretation, particularly due to the use of multiple separate analyses (ANOVA and t-tests), which complicated the interpretation of p-values, effect sizes, and between- versus within-group comparisons.

In response to this comment, we have thoroughly revised the statistical approach and reanalysed the data using linear mixed-effects models (LMMs), which provide a more appropriate framework for this repeated-measures design. This approach allows simultaneous modelling of group, time, and group × time interaction effects, while accounting for inter-individual variability.

As a result of this reanalysis:

• All p-values reported in the manuscript have been updated and are now derived from the LMMs.
• Effect sizes are now reported as regression coefficients (β) with corresponding 95% confidence intervals (CIs), replacing the previously reported Cohen’s d values, which were based on separate comparisons and may have led to inconsistencies.
• The interpretation of results has been revised to clearly distinguish between main effects, interaction effects, and post hoc comparisons.
• The analysis now explicitly focuses on the group × time interaction as the primary inferential parameter, in line with the reviewer’s recommendation and best practices for longitudinal designs.
• Post hoc analyses are only presented where significant main or interaction effects were identified, and are clearly specified as between-group comparisons at specific time points, avoiding ambiguity.

Regarding the specific examples mentioned by the reviewer:

• The previously reported Cohen’s d = 1.75 for immediate pain intensity has been removed, as it was derived from a separate t-test and not from the longitudinal model. The revised analysis shows a significant group × time interaction at the immediate post-intervention time point (β = -1.34, 95% CI [-2.56, -0.11], p = 0.032), which more accurately reflects the between-group difference within the repeated-measures framework.
• The interpretation of PPT at 1 hour has been clarified. In the revised manuscript, this result is explicitly reported as a between-group difference at a specific time point, derived from post hoc comparisons following the LMM, rather than a within-group change.

Overall, these revisions ensure that all statistical results are internally consistent, appropriately interpreted, and aligned with the study design. The Statistical Analysis and Results sections have been fully updated to reflect these changes.

Comments 5: Report mean differences with 95% confidence intervals

The manuscript would be improved by reporting between-group mean differences with 95% confidence intervals, especially for:

immediate pain after dry needling;

changes in PPT;

pain intensity at 1 h, 6 h, and 24 h.

This would help readers better understand the precision and clinical relevance of the findings.

Response: We thank the reviewer for this helpful suggestion.

In response, we have complemented the reporting of the linear mixed-effects models by including between-group mean differences with corresponding 95% confidence intervals (CIs) at clinically relevant time points. Specifically, these estimates are now reported for:

• pain intensity immediately after the intervention (primary outcome),
• pressure pain threshold (PPT) changes at each time point, and
• pain intensity at 1 h, 6 h, and 24 h follow-up

These values were derived from the estimated marginal means obtained from the linear mixed-effects models and provide a more clinically interpretable measure of the magnitude and precision of between-group differences.

Importantly, these results are fully consistent with the main findings of the model, particularly the significant between-group difference in pain intensity immediately after the intervention and the absence of sustained differences over time.

The Results section has been updated accordingly to include these mean differences and their 95% confidence intervals.

Comments 6: Revise the interpretation of PPT

The interpretation of pressure pain threshold needs clarification. A reduction in PPT usually indicates increased mechanical sensitivity, not hypoalgesia.

The results appear to support an immediate reduction in self-reported procedural pain, but they do not show a clear and consistent hypoalgesic effect on PPT. This should be reflected in the abstract, discussion, and conclusion.

Response: s Thank you very much for your comment. The interpretation of the PPT has been amended to explain that there was a significant increase in the PPT and to include a sentence introducing the differences between PPT and self-reported pain.

“Among the results found in this study, we did not find significant differences in PPT between groups either immediately, although there were significant differences in immediate reported pain. This reveals that differential mechanisms could exist between self-reported pain and increased mechanical sensitivity during IVR intervention.”

 

Comments 7: The sample consisted of healthy young adults with latent myofascial trigger points. Therefore, the findings cannot be directly generalized to patients with myofascial pain syndrome, chronic pain, anxiety, or needle phobia.

Some statements about clinical implementation, anxiety reduction, fear of needles, healthcare costs, or broader clinical use are too strong because these variables were not measured. These points should be presented as hypotheses for future research.

Response 7: We appreciate your feedback. The impossibility of extrapolating these results to other populations is included as the first limitation of the study.

“Despite its relevant contributions, this study has several limitations that should be considered. First, the sample of healthy young participants may limit the extrapolation of the results, particularly in the chronic pain population, myofascial pain syndrome or needle phobia”

On the other hand, we also included that a statement to clarified that effects on anxiety, fear and expectancy should be explored in future studies.

“Nevertheless, since this study did not include measures of anxiety, fear or expectancy, future studies should include these variables in order to examine these effects.”

 

Comments 8: The control group does not control for placebo, attention, or expectancy effects

The experimental condition included several components: immersive VR, nature exposure, music, guided breathing, visual feedback, novelty, and distraction. The control group received dry needling only.

Therefore, the observed effect cannot be attributed specifically to the nature-based IVR environment. It may also be explained by distraction, relaxation, breathing, expectancy, or novelty effects.

This limitation should be discussed more clearly. Future studies should consider comparator groups such as sham VR, non-immersive video, breathing-only control, headset-only control, or neutral VR.

Response 8:  Thank you very much for your suggestions. The study’s limitations have been expanded to explain that the possible passive effect of the intervention was not controlled for, given the differences between both groups. In addition, a statement has been included to explicitly address these differences between the interventions.

“Since the control group only received the DN intervention, some of the components of the IVR group such as the nature-based IVR environment, music, guided breathing, visual feedback or novelty may significantly influence the differences between groups.”

“Third, the potential placebo effect of the IVR intervention on pain relief has not been explored in the present study. Finally, other possible influences, such as anxiety or fear, as well as other potential mediators of pain reduction, such distraction, relaxation, breathing, expectancy, or novelty effects of IVR  during DN, have not been examined in our study. Future studies should include comparator groups such as sham VR, non-immersive nature video or breathing-only control for more rigorous placebo-controlled response.”

 

Comments 9: Provide more detail on dry needling dosage

The dry needling protocol needs more detail to ensure reproducibility and to confirm that both groups received a comparable stimulus.

The authors should report:

actual number of needle insertions; number of local twitch responses; actual duration of needling; whether tolerance differed between groups; whether IVR allowed greater tolerance and therefore changed the DN dose; whether the same physiotherapist treated all participants; clinician experience; adverse events.

This is relevant because IVR could change pain tolerance and indirectly modify the dry needling stimulus..

Response: We thank the reviewer for this valuable suggestion. We agree that a more detailed description of the dry needling intervention improves reproducibility and facilitates interpretation of the results. Accordingly, in addition to the information of the Methods section, we have expanded the Results section to clarify the dry needling dosage and intervention procedures.

“In all participants, the maximum of 20 needle insertions was completed in less than one minute, which determined the endpoint of the intervention. Although the number of local twitch responses and the exact duration were not recorded, at least one local twitch response was observed in all cases.”

The lack of recording of the number of local twitch responses has been acknowledged as a limitation and added to the corresponding section of the manuscript.

Tolerance to the intervention was not formally assessed beyond the pain experienced during the procedure; however, all participants completed the 20 needle insertions, ensuring consistency of the protocol across both groups. All interventions were performed by the same experienced physiotherapist, and no adverse events were reported. This information has been clarified and expanded in the Methods and Results sections.

 

Comments 10: Improve the description of trigger point identification

The criteria used to identify latent myofascial trigger points should be described more clearly.

The authors should specify:

diagnostic criteria used; whether taut band, hypersensitive spot, referred pain, or local twitch response were required; examiner experience; whether reliability was assessed; side assessed; dominance; previous exposure to dry needling or VR.

Response: We thank the reviewer for this important comment. The Methods section has been revised to clearly describe the criteria used to identify latent myofascial trigger points.

Latent MTrPs were identified based on the presence of a palpable taut band and a hypersensitive spot within the muscle, together with the elicitation of referred pain upon palpation, in accordance with consensus-based recommendations. As participants were asymptomatic, the absence of spontaneous pain was ensured, and recognition of the evoked pain as familiar pain was not required.

We have also clarified that the assessment was performed by an experienced physiotherapist with specific training in dry needling and myofascial pain examination.

Previous exposure to dry needling or virtual reality was not assessed, and no reliability testing of the diagnostic procedures was conducted; these aspects have now been acknowledged as limitations in the revised manuscript.

 

Comments 11: Report adverse events

The manuscript should explicitly report whether any adverse events occurred during or after dry needling or IVR, including bleeding, bruising, vasovagal symptoms, dizziness, nausea, cybersickness, post-needling soreness, or discomfort from the headset.

If no adverse events occurred, this should be stated.

Response: We sincerely thank the reviewer for their suggestion. No adverse effects were reported. However, the following has been explicitly reported:

No adverse effects were reported beyond the expected discomfort or mild pain during and after the dry needling technique.

 

Comments 12: Align the discussion with the actual results

The discussion should focus on the main supported finding: IVR reduced immediate self-reported pain during/after dry needling.

However, the effect did not clearly persist in the short term, and PPT did not show a consistent pattern. Proposed mechanisms such as autonomic modulation, anxiety reduction, or fear reduction should be discussed more cautiously, since these variables were not directly measured.

Response: Thank you for your suggestion. The discussion has been revised to reflect the results found.

“This study aimed to investigate the immediate and short-term hypoalgesic effects of nature-based IVR on different measures of pain modulation in acute procedural pain after DN, with a primary focus on immediate post-intervention pain intensity. The main finding was that participants in the DN+IVR group reported significantly lower pain intensity immediately after the intervention compared to the DN group. However, this effect was not maintained over time, as no significant between-group differences were observed at subsequent follow-up time points. Additionally, no consistent be-tween-group differences were found for PPT. These findings suggest that nature-based IVR reduces pain intensity during DN offering a promising venue to reduce acute procedural pain following needle-related procedures.”

Likewise, it has been explained that the mechanisms behind these results could be due to distraction and autonomic modulation, based on previous literature, although these mechanisms have not been directly measured. Likewise, this has been reformulated as possible hypotheses and it has been suggested that future studies should include these measures.

“Thus, nature-based IVR could reduce pain during DN, mediated by distraction and autonomous modulation. Subsequent investigations should need to examine the effect of IVR on the autonomous activation derived from DN.”

 

Minor comments:

Comments 13: Remove the template text at the beginning of the Results section.

Response: This was a typo, which has been removed. Thank you for the feedback.

 

Comments 14: Remove the “Patents” section if it is not applicable.

Response:  Thank you. This section has been deleted

 

Comments 15: Correct the “Institutional Review Board Statement”, as it currently seems to include funding information.

Response: Agradecemos su sugerencia. Hemos corregido este apartado incluy ndo la información adecuada.

 

Comments 16: Remove unrelated abbreviations such as MDPI, DOAJ, TLA, and LD.

Response: Thank you for your suggestion. We agree that those abbreviations should not be on the list, so we have removed them.

 

Comments 17: Use “PPT” consistently. In some places, “PTT” appears.

Response: It has been reviewed and corrected to consistently use the term PPT

 

Comments 18: Do not use “pressure pain threshold” and “pain tolerance threshold” interchangeably.

Response: Hemos corregido el texto para usar de manera consistente “pressure pain threshold”

 

Comments 19: Revise the abstract for grammar and clarity. For example, “Our results shows” should be “Our results show”.

Response: We thank the reviewer for this comment. The sentence in question has been removed as part of the revisions made to this section in response to other reviewer comments, and it is no longer present in the manuscript.

 

Comments 20: Revise the phrase “no differences between groups were found at certain time series”, as it is unclear.

Response: Thank you for the comment.  As in the previous comment, the sentence in question has been removed as part of the revisions made to this section, and it is no longer present in the manuscript.

 

Comments 21: Improve table formatting, especially Table 2.

Response: We thank the reviewer for this suggestion. The format of Tables 1 and 2 has been reviewed, and it was noted that the data reporting format (mean, SD, and CI) had not been consistently followed. The format has been standardized.

 

Comments 22: Check consistency between the text, tables, and figures.

Response: We thank the reviewer for the comment. The text of the results section has been modified in accordance with the additional analyses suggested in another comment, requesting a linear mixed-effects model. Additionally, the order of the sections concerning pain and pressure pain thresholds has been changed. The figures and tables have been reviewed, and the table formatting errors have been corrected.

 

Comments 23: Use the journal’s required citation style consistently. Some citations appear in author-year format.

Response: We sincerely thank the reviewer for their review of these aspects. Thanks to this, we have been able to verify that some references were indeed not in the correct format (also related to the following comment). It has also been verified that the reference list adheres to the journal's style guidelines.

 

Comments 24: Check that all cited references are included in the reference list.

Response: Thank you for your comment. We have reviewed the manuscript and confirmed that some references were not inserted correctly and are not included in the reference list. We have corrected the issue.

 

Comments 25: Consider replacing “muscle spasm” with “local twitch response”, if that is the intended term.

Response: We thank the reviewer for this suggestion. The term has been revised accordingly, replacing “muscle spasm” with “local twitch response” throughout the manuscript where appropriate.

 

Comments 26: Use “participants” rather than “patients”, since the sample consisted of healthy individuals.

Response: We thank the reviewer for this comment. We have carefully revised the manuscript to ensure that the term “participants” is consistently used when referring to the study sample. The term “patients” is only used when referring to the clinical context and potential applicability of the intervention.

 

Comments 27: Make the conclusion more cautious.

Response: We thank the reviewer for this comment. The conclusion has been revised to adopt a more cautious interpretation of the findings, avoiding overgeneralization and better reflecting the scope and limitations of the study.

Thus, we have modified the second sentence from “Our findings support that IVR reduces acute procedural pain of DN and may mitigate the most common adverse effects.” to “Our findings provides preliminary evidence that IVR may reduce acute procedural pain associated with DN and may mitigate the most common adverse effects.”

The “conclusion” section of the abstract has been also modified.

 

Comments 28: Check the hyphens on words that shouldn`t be there, for example in the abstract: be-twee

Response: We thank the reviewer for pointing this out. These incorrect hyphenations (e.g., “be-tween”, “ap-proximately”, “re-searcher”)were due to a technical issue during the formatting of the manuscript into the journal template. All such errors have been carefully revised and corrected throughout the manuscript.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

There remains a serious issue in the reporting of the PPT results. The authors state that the between-group difference in PPT at 1 hour was statistically significant (p = 0.011), but the reported 95% confidence interval for the same estimate is [-0.90, 1.76], which includes zero. If these values refer to the same model estimate and statistical test, a significant p-value of 0.011 would generally not be expected to coincide with a 95% confidence interval that includes zero. The authors should therefore recheck the model output, the pairwise comparisons, and the method used to calculate confidence intervals, and should clarify this inconsistency in the manuscript.

Reference 22 appears to contain citation-management or metadata-import errors. The author names are not presented in a recognizable bibliographic format, and “PubMed” appears to have been entered as the journal/source, although PubMed is a database rather than the journal title. The authors should verify the original article and provide the correct author names, journal title, year, volume, pages or article number, and DOI.

Author Response

Comment 1: There remains a serious issue in the reporting of the PPT results. The authors state that the between-group difference in PPT at 1 hour was statistically significant (p = 0.011), but the reported 95% confidence interval for the same estimate is [-0.90, 1.76], which includes zero. If these values refer to the same model estimate and statistical test, a significant p-value of 0.011 would generally not be expected to coincide with a 95% confidence interval that includes zero. The authors should therefore recheck the model output, the pairwise comparisons, and the method used to calculate confidence intervals, and should clarify this inconsistency in the manuscript.

Response: We thank the reviewer for identifying this inconsistency. Upon review of the statistical reporting, we found that the previously reported p-value and confidence interval were derived from different analytical approaches and therefore should not have been interpreted together. To ensure consistency, we revised the Results section so that the interpretation is based on the linear mixed-effects model framework and the corresponding between-group estimates.

Specifically, we removed the isolated emphasis on the 1-hour comparison and revised the text to highlight the overall pattern of results. Although a small between-group difference was observed at 1 hour, the corresponding confidence interval included zero and the overall group × time interaction was not statistically significant. Therefore, this finding was interpreted cautiously and not considered evidence of a differential effect of the intervention over time.

The revised Results section now emphasizes the absence of significant group × time interactions for PPT and reports that between-group differences were small across all assessment time points, which is consistent with the estimated confidence intervals and the longitudinal mixed-model analysis.

We are grateful to the reviewer for highlighting this issue, which has improved the consistency and clarity of the statistical reporting.

 

Comment 2: Reference 22 appears to contain citation-management or metadata-import errors. The author names are not presented in a recognizable bibliographic format, and “PubMed” appears to have been entered as the journal/source, although PubMed is a database rather than the journal title. The authors should verify the original article and provide the correct author names, journal title, year, volume, pages or article number, and DOI.

Response: The authors thank the reviewer for this comment. Indeed, there was an error in how the bibliographic manager had captured the reference. The issue has been corrected.

Reviewer 2 Report

Comments and Suggestions for Authors

Thank you for the revision. Most of my previous comments have been adequately addressed, and the manuscript has improved considerably. The explanation provided for the sample-size estimation is acceptable for this initial study.

I recommend addressing the following points:

1. Clarify the PPT result at 1 hour.
The reported p value (p = 0.011) is not consistent with the 95% CI (−0.90 to 1.76), which includes zero. Please verify whether this refers to a between-group or within-group comparison and report it consistently throughout the manuscript.

2. Moderate the clinical conclusion.
The main supported finding is an immediate reduction in procedural pain. Statements regarding anxiety, fear of needles, adverse events, opioid use, healthcare costs, or broader clinical implementation should remain clearly hypothetical, as these outcomes were not measured.

3. Use consistent terminology regarding the timing of the intervention.
The IVR intervention was applied during dry needling, whereas pain was assessed immediately after the procedure. Please ensure that this distinction is described consistently throughout the manuscript.

4. Perform a final English-language revision.
Some grammatical and duplicated expressions remain and should be corrected in the clean version. Some grammatical and duplicated expressions remain, such as “may reduces,” “Our findings provides,” “carried outperformed,” and “patients who whould.” Please correct these in the clean version.

Author Response

General comment: Thank you for the revision. Most of my previous comments have been adequately addressed, and the manuscript has improved considerably. The explanation provided for the sample-size estimation is acceptable for this initial study.

Response: We thank the reviewer for taking the time to review again this manuscript.

 

Comment 1: Clarify the PPT result at 1 hour.

The reported p value (p = 0.011) is not consistent with the 95% CI (−0.90 to 1.76), which includes zero. Please verify whether this refers to a between-group or within-group comparison and report it consistently throughout the manuscript.

Response: We thank the reviewer 2 for identifying this inconsistency. As described in response to a similar comment from another reviewer, opon review of the statistical reporting, we found that the previously reported p-value and confidence interval were derived from different analytical approaches and therefore should not have been interpreted together. To ensure consistency, we revised the Results section so that the interpretation is based on the linear mixed-effects model framework and the corresponding between-group estimates.

Specifically, we removed the isolated emphasis on the 1-hour comparison and revised the text to highlight the overall pattern of results. Although a small between-group difference was observed at 1 hour, the corresponding confidence interval included zero and the overall group × time interaction was not statistically significant. Therefore, this finding was interpreted cautiously and not considered evidence of a differential effect of the intervention over time.

The revised Results section now emphasizes the absence of significant group × time interactions for PPT and reports that between-group differences were small across all assessment time points, which is consistent with the estimated confidence intervals and the longitudinal mixed-model analysis.

Therefore, we are grateful both reviewers for highlighting this issue, which has improved the consistency and clarity of the statistical reporting.

 

Comment 2: Moderate the clinical conclusion.

The main supported finding is an immediate reduction in procedural pain. Statements regarding anxiety, fear of needles, adverse events, opioid use, healthcare costs, or broader clinical implementation should remain clearly hypothetical, as these outcomes were not measured.

Response: We thank the reviewer for the suggestion. We agree that the message could be misinterpreted in some phrases of the conclusion. We have added to the conclusion that the pain is "self-reported," removed the phrase "and may mitigate the most common adverse effects," and verified that, in the discussion, when referring to other effects such as fear, anxiety, or benefits to the healthcare system, it is explicitly stated that these were not evaluated in this study.

 

Comment 3: Use consistent terminology regarding the timing of the intervention.

The IVR intervention was applied during dry needling, whereas pain was assessed immediately after the procedure. Please ensure that this distinction is described consistently throughout the manuscript.

Response: We thank the reviewer for this important comment. The manuscript has been carefully revised to improve clarity regarding the timing of the intervention and outcome assessment. Specifically, we have refined the use of terms such as “during” and “following” throughout the text to avoid ambiguity.

The study objectives and outcome descriptions have been reworded to clearly indicate that immersive virtual reality (IVR) was applied during the dry needling (DN) procedure, while pain intensity was assessed immediately after the intervention but referred explicitly to the pain experienced during the procedure. In addition, we have clarified that short-term follow-up assessments were conducted to evaluate the evolution of pain intensity and pressure pain threshold (PPT) over time.

 

Comment 4: Perform a final English-language revision.

Some grammatical and duplicated expressions remain and should be corrected in the clean version. Some grammatical and duplicated expressions remain, such as “may reduces,” “Our findings provides,” “carried outperformed,” and “patients who whould.” Please correct these in the clean version.

Response: The authors thank the reviewer for this suggestion. We have reviewed the English and writing style again with the help of an expert, identifying some errors that required correction. We have also improved some expressions. We hope that the manuscript now shows a marked improvement in writing quality.