The Effect of an Immersive Virtual Reality Physical Activity Intervention on Anthropometric Variables, Physical Fitness, and Blood Pressure in College Students: A Randomized Controlled Trial

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Title: Effect of an Immersive Virtual Reality Physical Activity Intervention on Anthropometric Variables, Physical Fitness, and Blood Pressure in College Students: A Randomized Controlled Trial

General Assessment

This manuscript investigates the effects of an immersive virtual reality based physical activity intervention on anthropometric variables, physical fitness, and blood pressure in university students using a randomized controlled design. The topic is highly relevant given the increasing sedentary behavior in young adults and the growing interest in technology-assisted exercise interventions. The 12-week intervention period, randomized controlled methodology, and assessment of multiple health-related outcomes constitute notable strengths. However, despite its potential contribution, the manuscript presents several important methodological, statistical, and reporting limitations that substantially weaken the confidence in the conclusions. Major revisions are required, particularly with respect to sample size justification, statistical transparency, control of confounding variables, precision of reporting, and physiological interpretation of the intervention.

Line 113: The manuscript lacks critical methodological controls:

• Time of day at which physical activity sessions and fitness assessments were conducted is not reported (except for blood pressure measurements). Given the known influence of circadian rhythms on physical performance and physiological variables, this information is essential.
• There is no description of how nutrition, hydration, caffeine intake, medication use, or prior physical activity were controlled before testing sessions. These uncontrolled factors substantially compromise internal validity.

Lines 146: The intervention is insufficiently described from a physiological perspective. The manuscript should include a clearer characterization of:

- Primary energy system contribution (aerobic vs anaerobic),

- Cardiovascular load and metabolic demands,

- Training structure in relation to expected physiological adaptations.

This clarification is essential for interpreting the observed improvements in VO₂, blood pressure, and body mass index.

Line 159: The control group is described only as maintaining “usual physical activity,” which is inadequate. Please provide detailed information regarding: (1) Frequency of weekly activity, (2) type of activities performed, (3) Typical intensity. Without this information, the interpretation of between-group differences remains uncertain.

Line 229: The manuscript reports a significant improvement in the 20-m shuttle test with p = 0.29, which is not statistically significant. This is a serious error and must be corrected.

Line 232:

• The statistical approach relies heavily on repeated t-tests without any correction for multiple comparisons, increasing the risk of Type I error. An appropriate correction strategy should be applied or justified.
• Effect sizes are inconsistently reported and contain apparent errors. For example (table 1), identical effect size values (d = 2.69) are reported for both VO₂ and the 20-m shuttle test, which is statistically improbable and suggests calculation or transcription mistakes.
• Table 1 must include mean ± standard deviation (SD) for all variables to ensure transparency, reproducibility, and proper interpretation of variability.

Line 234:  The lack of strength improvements should be discussed in relation to the training stimulus, volume, and mechanical loading characteristics.

The limitations section should be expanded to systematically address the absence of control over nutrition, baseline physical activity, sleep, and psychosocial factors.

Author Response

REVIEWER 1

Title: Effect of an Immersive Virtual Reality Physical Activity Intervention on Anthropometric Variables, Physical Fitness, and Blood Pressure in College Students: A Randomized Controlled Trial

General Assessment

This manuscript investigates the effects of an immersive virtual reality based physical activity intervention on anthropometric variables, physical fitness, and blood pressure in university students using a randomized controlled design. The topic is highly relevant given the increasing sedentary behavior in young adults and the growing interest in technology-assisted exercise interventions. The 12-week intervention period, randomized controlled methodology, and assessment of multiple health-related outcomes constitute notable strengths. However, despite its potential contribution, the manuscript presents several important methodological, statistical, and reporting limitations that substantially weaken the confidence in the conclusions. Major revisions are required, particularly with respect to sample size justification, statistical transparency, control of confounding variables, precision of reporting, and physiological interpretation of the intervention.

A: Dear reviewer, we appreciate your feedback, it has been a great help in improving our work. Below we give answers to each one.

Line 113: The manuscript lacks critical methodological controls:

• Time of day at which physical activity sessions and fitness assessments were conducted is not reported (except for blood pressure measurements). Given the known influence of circadian rhythms on physical performance and physiological variables, this information is essential.

A: Thank you for your comment. We have added the requested information between the methodology chapter.

 

• There is no description of how nutrition, hydration, caffeine intake, medication use, or prior physical activity were controlled before testing sessions. These uncontrolled factors substantially compromise internal validity.

A: Thank you for your comment. We understand the importance of these variables for the internal validity of our study, so in the methodology chapter we add information on how they were controlled before the development of each session. We added the following information: "Participants were asked to maintain their usual eating and hydration patterns. Avoid major changes in your diet. Attend hydrated and hydrate during and after the sessions. Avoid caffeine consumption before each session. Do not perform physical activity before evaluations (pre and post-intervention). Do not perform any other type of physical activity during the 12 weeks of intervention. In the case of medication, maintain the same dose during the intervention, and in case of changes, inform the research team. In addition, each participant carried out their three weekly sessions at the same time".

 

 

 

Lines 146: The intervention is insufficiently described from a physiological perspective. The manuscript should include a clearer characterization of:

- Primary energy system contribution (aerobic vs anaerobic),

- Cardiovascular load and metabolic demands,

- Training structure in relation to expected physiological adaptations.

This clarification is essential for interpreting the observed improvements in VO₂, blood pressure, and body mass index.

A: Thank you for your comment. We have added information about the physiological description of the training session and its contribution to the intervention. We add the following: "Due to the total duration (40 minutes) and the sustained repetition of efforts that are mixed with periods of active recovery, the intervention can be classified as high-intensity aerobic training, although at the peaks of greater demand there is a contribution from the anaerobic energy system. On the other hand, it is consistent with the evidence that describes that high-intensity training integrates a mixed participation of both energy systems and provokes sufficient stimuli to produce relevant cardiorespiratory adaptations [31]. Likewise, intensities worked between 80% and 95% generate a substantial increase in energy expenditure and a marked ventilatory effort, which favors improvements in maximum oxygen volume and cardiorespiratory efficiency [31]. Finally, the systematic structure of each session, including progressive warm-up, high effort intervals, and active recovery is designed to promote sustained cardiovascular and metabolic adaptations, consistent with reductions in blood pressure reported in similar high-intensity programs [32].

 

Line 159: The control group is described only as maintaining “usual physical activity,” which is inadequate. Please provide detailed information regarding: (1) Frequency of weekly activity, (2) type of activities performed, (3) Typical intensity. Without this information, the interpretation of between-group differences remains uncertain.

A: Thank you for your comment: We have added information about what was indicated to the control group. In the methodology section, we added the following: "during the duration of the study they were instructed not to start performing any structured physical activity program, nor to voluntarily increase the time and intensity of the physical activity they performed daily, which they were reminded weekly through messages to their mobile phones. In addition, due to its importance, it was added that one of the limitations of our study was the lack of control over possible confounding factors, among which is the failure to measure the levels of physical activity in the control group objectively or self-reported.

 

Line 229: The manuscript reports a significant improvement in the 20-m shuttle test with p = 0.29, which is not statistically significant. This is a serious error and must be corrected.

A: Thank you for your comment. Because new analyses were performed, the error no longer exists.

Line 232: 

• The statistical approach relies heavily on repeated t-tests without any correction for multiple comparisons, increasing the risk of Type I error. An appropriate correction strategy should be applied or justified.

A: We appreciate this comment, as it allowed us to reconsider the statistical analyses performed and thereby reduce the risk of Type I error. Accordingly, we revised the analyses as follows. Comparisons of baseline characteristics between groups were assessed using independent-samples Student’s t tests. The effect of the intervention was evaluated using an analysis of covariance (ANCOVA), with the post-intervention value as the dependent variable, group (intervention vs control) as the factor, and the baseline value of the variable as the covariate. The group effect coefficient (β), its 95% confidence interval, and the p value were reported. To control for multiple comparisons across outcomes, ANCOVA p values were adjusted using the Holm–Bonferroni method; additionally, Benjamini–Hochberg false discovery rate (FDR) adjustment was reported as a complementary analysis. As a sensitivity analysis, between-group differences in change (Δ = post–pre) were compared using Welch’s t test for independent samples, and effect size was estimated using Cohen’s d [34]. Statistical significance was set at α = 0.05 (two-tailed), with significance interpreted primarily based on adjusted p values. Analyses were conducted using SPSS v29.

The revised analyses changed our results. Specifically, significant changes were observed only in variables related to cardiorespiratory fitness. Accordingly, the corresponding modifications were made to the Discussion, Conclusions, and Abstract sections.

 

• Effect sizes are inconsistently reported and contain apparent errors. For example (table 1), identical effect size values (d = 2.69) are reported for both VO₂ and the 20-m shuttle test, which is statistically improbable and suggests calculation or transcription mistakes.

A: Thank you for your comment. There was a transcription error. Because the statistical analyses were performed again, that error no longer exists.

 

• Table 1 must include mean ± standard deviation (SD) for all variables to ensure transparency, reproducibility, and proper interpretation of variability.

A: Thank you for your comment. We have added a table 1 with the baseline characteristics of the total sample, as well as of the two groups. We added a table 2, where you can see the changes in the second evaluation, plus the p values found. In both tables we have incorporated half ± SD.

Line 234:  The lack of strength improvements should be discussed in relation to the training stimulus, volume, and mechanical loading characteristics.

A: We agree that the absence of significant improvements in manual grip strength should be analyzed in the light of the characteristics of the training stimulus applied. The intervention was predominantly oriented to the cardiorespiratory component, with an emphasis on dynamic, high-frequency movements with low external mechanical load, which probably did not provide sufficient stimulus in terms of volume, intensity, and mechanical tension to induce significant adaptations in muscle strength. This aspect has been incorporated and developed in greater detail in the Discussion section, highlighting the principle of specificity of training and the need for progressive overload stimuli to generate improvements in strength.

The limitations section should be expanded to systematically address the absence of control over nutrition, baseline physical activity, sleep, and psychosocial factors.

A: This section was expanded to systematically address the lack of control over potentially confounding variables, including nutritional intake, baseline levels of physical activity, sleep patterns, and psychosocial factors.

Reviewer 2 Report

Comments and Suggestions for Authors

Hello, dear authors!

This study is a randomized controlled trial examining the effects of physical activity using immersive virtual reality on anthropometric measures, physical fitness, and blood pressure in students.

My comments are as follows:
1. The VR hardware is not described: the model, screen refresh rate, and safety measures should be specified.
2. To improve the accuracy of the study, a subgroup analysis is needed to assess the impact of gender (including physical fitness) and baseline activity level.
3. Participants with visual impairments were excluded, but the specific methods for testing vision (acuity, binocular vision, color perception, flicker sensitivity) are not described. Particularly important for flickering optical devices, there is no information on whether photosensitivity (risk of triggering epileptic seizures) was assessed.
4. It is not stated whether vestibular stability or susceptibility to cybersickness was assessed, which could impact tolerability and safety.
5. No safety assessment: How was safety ensured during intense movements in VR?

Author Response

REVIEWER 2

Hello, dear authors!

This study is a randomized controlled trial examining the effects of physical activity using immersive virtual reality on anthropometric measures, physical fitness, and blood pressure in students.

A: Dear Reviewer, we are very grateful for your feedback, as it has been helpful in improving our work. Best regards.

 

My comments are as follows:
1. The VR hardware is not described: the model, screen refresh rate, and safety measures should be specified.
A: Thank you for your comment. We have added what is requested in section 2.5.2.

2. To improve the accuracy of the study, a subgroup analysis is needed to assess the impact of gender (including physical fitness) and baseline activity level.
   A: Thank you for your comment. We have conducted subgroup analyses to determine the impact of gender. These analyses have been incorporated as supplementary tables. In addition, information on the results found in the discussion chapter has been added.

 

3. Participants with visual impairments were excluded, but the specific methods for testing vision (acuity, binocular vision, color perception, flicker sensitivity) are not described. Particularly important for flickering optical devices, there is no information on whether photosensitivity (risk of triggering epileptic seizures) was assessed.

A: The exclusion of subjects with visual impairments was based on an initial clinical evaluation through self-report, using a history that included a history of diagnosed visual impairment, epilepsy, seizures, photosensitive migraine, or other neurological conditions that could contraindicate the use of immersive virtual reality. No specific instrumental assessments of visual acuity, binocular vision, or photosensitivity were performed, which is a limitation of the study. This information is included in the method chapter.

4. It is not stated whether vestibular stability or susceptibility to cybersickness was assessed, which could impact tolerability and safety.

A: As in the previous response, problems of susceptibility to cybersickness were identified through self-reporting. 

 

5. No safety assessment: How was safety ensured during intense movements in VR?

A: We appreciate this observation. While no specific formal safety/tolerability scale was applied (e.g., standardized cybersickness questionnaires), safety was ensured by an operational protocol during all sessions: (i) continuous face-to-face supervision by a Physical Education professional, (ii) use of a clear and delimited space, (iii) prior instruction on technique, movement, and use of the device,  (iv) progression of effort by levels (beginner – intermediate - advanced) and monitoring of intensity by heart rate, and (v) predefined criteria for stopping symptoms such as dizziness, nausea, disorientation, chest pain or discomfort. In addition, no adverse events were recorded during the intervention, nor were any relevant incidents reported.

Reviewer 3 Report

Comments and Suggestions for Authors

Dear Authors,

I appreciate the opportunity to review your work. Following its thorough reading and analysis, I would like to provide a number of recommendations and suggestions. I would appreciate it if you would take my comments into consideration, as I believe they may help to improve and strengthen the manuscript.

Introduction

The introduction presents a clear and well-structured narrative by contextualizing the dependent variables (anthropometric indicators, physical fitness, and blood pressure) and their relationship with the independent variable (physical activity, specifically immersive virtual reality–based physical activity). It concludes by identifying the existing knowledge gap in university students, which justifies the conduct of this study.

 

Metodology

The methodological section is adequately described; however, it could benefit from a clearer reorganization of the information. Specifically:

i) Section 2.5 on randomization could be integrated at the point where Figure 1 is referenced, so that the random allocation of participants using EPIDAT software and the final sample composition are described together (Figure 1).

ii) In addition, the duration of the intervention (Section 2.6.3) is mentioned in several parts of the manuscript; therefore, this subsection could be omitted to avoid repetition. However, the time period during which the study was conducted (months/year) is not specified and should be clearly reported.

iii) Furthermore, Section 2.7 describing the procedure should be presented at the beginning of the intervention, as it refers to the signing of the informed consent prior to study implementation. Likewise, the authors should specify how university students were contacted (e.g., institutional email, social media, snowball sampling, etc.).

• The inclusion criteria specify an age range of 18–25 years. Out of curiosity, why were older university students not eligible for inclusion?
• The manuscript states that the intervention lasted 12 weeks with three sessions per week; however, the location where these sessions took place should be specified (e.g., at university facilities, a clinic, or a sports center).

 

Results

• In the Results section, it would be appropriate to consider including a table presenting the participants’ sociodemographic characteristics, which would allow for a better definition of the sample. Variables such as age, sex, faculty of origin, or whether the degree program is related to the health sciences could be included, as this factor may lead to differences among participants. In this regard, was this information considered during data collection?

Discussion

• The discussion is appropriately supported with examples from previous studies linking the adoption of healthy lifestyle behaviors to improved cardiovascular risk profiles. Considering that obesity itself constitutes a cardiovascular risk factor, it may be of interest for future studies to analyze which healthy lifestyle behaviors are actually present in this group of adolescents. Due to their condition, certain behaviors, such as engaging in physical activity or following a healthy diet, may be less prevalent.
• It is recommended to include the DOI in the references when available, to facilitate locating the sources.

In conclusion, I would like to congratulate the authors on this interesting work, which may contribute relevant knowledge regarding the approach that strategies aimed at promoting healthy lifestyles should adopt, by combining physical activity with virtual reality in order to achieve benefits in terms of cardiovascular risk reduction in a young population.

Author Response

REVIEWER 3

Dear Authors,

I appreciate the opportunity to review your work. Following its thorough reading and analysis, I would like to provide a number of recommendations and suggestions. I would appreciate it if you would take my comments into consideration, as I believe they may help to improve and strengthen the manuscript.

Introduction

The introduction presents a clear and well-structured narrative by contextualizing the dependent variables (anthropometric indicators, physical fitness, and blood pressure) and their relationship with the independent variable (physical activity, specifically immersive virtual reality–based physical activity). It concludes by identifying the existing knowledge gap in university students, which justifies the conduct of this study.

Metodology

The methodological section is adequately described; however, it could benefit from a clearer reorganization of the information. Specifically:

2. i) Section 2.5 on randomization could be integrated at the point where Figure 1 is referenced, so that the random allocation of participants using EPIDAT software and the final sample composition are described together (Figure 1).

A: Thank you for your comment. We do what we suggested.

 

2. ii) In addition, the duration of the intervention (Section 2.6.3) is mentioned in several parts of the manuscript; therefore, this subsection could be omitted to avoid repetition. However, the time period during which the study was conducted (months/year) is not specified and should be clearly reported.

A: Thank you for your comment. We have removed section 2.6.3. The period in which the intervention was carried out was between the months of August and October 2025. This information was added in the first paragraph of the methodology chapter.

 

iii) Furthermore, Section 2.7 describing the procedure should be presented at the beginning of the intervention, as it refers to the signing of the informed consent prior to study implementation. Likewise, the authors should specify how university students were contacted (e.g., institutional email, social media, snowball sampling, etc.).

A: Thank you for your comment. Because of the suggestions, we have moved the procedure section to the place where the procedure is described. In addition, we have added what is requested (how university students were contacted) when describing the participants (section 2.3.).

• The inclusion criteria specify an age range of 18–25 years. Out of curiosity, why were older university students not eligible for inclusion?

A: Thank you for your comment. The choice was because this age range represents the largest proportion of the traditional university population and is frequently used in intervention studies in this context.

• The manuscript states that the intervention lasted 12 weeks with three sessions per week; however, the location where these sessions took place should be specified (e.g., at university facilities, a clinic, or a sports center).

A: Thank you for your comment. All sessions were held in the virtual reality lab. We have added this information in the procedure section.

Results

• In the Results section, it would be appropriate to consider including a table presenting the participants’ sociodemographic characteristics, which would allow for a better definition of the sample. Variables such as age, sex, faculty of origin, or whether the degree program is related to the health sciences could be included, as this factor may lead to differences among participants. In this regard, was this information considered during data collection?

A: Thank you for your comment. We have added a table where the baseline characteristics of the sample are specified. In this table we add information on the sex, number and percentage of participants. In section 2.5.1. The number of participants per race is described.

Discussion

• The discussion is appropriately supported with examples from previous studies linking the adoption of healthy lifestyle behaviors to improved cardiovascular risk profiles. Considering that obesity itself constitutes a cardiovascular risk factor, it may be of interest for future studies to analyze which healthy lifestyle behaviors are actually present in this group of adolescents. Due to their condition, certain behaviors, such as engaging in physical activity or following a healthy diet, may be less prevalent.

A: Thank you for your comment. We have reinforced the projections section, highlighting the need for future studies to comprehensively evaluate patterns of physical activity, diet, sleep and other health-related behaviors, to identify which habits are less prevalent and how these can modulate the cardiovascular risk profile in overweight or obese university populations.

• It is recommended to include the DOI in the references when available, to facilitate locating the sources.

A: Thank you for your comment. We have not added the DOI as the journal standards do not require them. In research that we have published in the same publisher, they have removed the DOI in print tests.

 

In conclusion, I would like to congratulate the authors on this interesting work, which may contribute relevant knowledge regarding the approach that strategies aimed at promoting healthy lifestyles should adopt, by combining physical activity with virtual reality in order to achieve benefits in terms of cardiovascular risk reduction in a young population.

A: Dear reviewer. We appreciate the comments made, as they have contributed to improving Our work.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors have successfully addressed all the concerns and suggestions raised in my previous report. The revisions have significantly improved the clarity and quality of the work. Therefore, I am pleased to recommend the manuscript for acceptance in its current form.