Review Reports - Effects of Halotherapy as an Adjunct to Preseason Training on Respiratory and Aerobic Outcomes in Elite Female Football Players: A Randomized Controlled Trial

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript investigates an original topic with potential practical relevance for sports medicine and exercise physiology. The randomized design, comprehensive respiratory assessment, and applied setting constitute important strengths. However, methodological reporting remains incomplete, some statistical interpretations require improvement, and parts of the discussion overstate mechanistic explanations that are not directly supported by the collected data. These issues are substantial but appear addressable through revision.
Major Comments

Study design and internal validity

Pg. 3–4 (Lines 99–149)- Although the study is presented as a randomized controlled trial, important methodological details remain insufficiently described.

Please clarify: the randomization procedure (sequence generation); allocation concealment; who performed randomization; whether outcome assessors were blinded; whether participants were blinded (or justify why this was impossible).

Because halotherapy is susceptible to placebo effects, the absence of a sham-halotherapy control group should be discussed as an important limitation.

Training load control

Pg. 4–5 (Lines 139–200) The training programme is only briefly described. Please provide:

weekly external load;
internal load (RPE or HR);
progression across the 12 weeks;
confirmation that both groups completed identical training loads.

Otherwise, differences may reflect unequal training exposure rather than halotherapy.

Phyiological mechanisms remain speculative

Pg. 14–15 (Lines 474–501) - The discussion proposes several physiological mechanisms involving:

mucociliary clearance;
oxygen extraction;
mitochondrial adaptations;
respiratory efficiency.

However, none of these variables were measured.

The discussion should clearly distinguish between: measured outcomes; hypotheses; and speculative mechanisms. Statements suggesting causal physiological mechanisms should be substantially moderated.

Clinical significance

Pg. 8–12 - Statistical significance is consistently reported. However, the manuscript does not adequately discuss:

minimal clinically important differences;
practical significance;
whether observed improvements translate into meaningful football performance.

Please strengthen the interpretation of practical relevance.

Generalizability

Pg. 15 (Limitations)-Although the authors mention some limitations, they underestimate their impact. The manuscript should further discuss:

single-club sample;
elite Turkish female players only;
preseason period only;
absence of long-term follow-up.

Generalization should therefore be more conservative.

CONSORT reporting

Although CONSORT is mentioned, several reporting items remain incomplete.

Please verify compliance with:

participant flow;
allocation concealment;
implementation;
blinding;
protocol deviations.

Minor Comments

Pg. 2 (Introduction)-The Introduction would benefit from a more critical review of previous evidence.

Include recent systematic reviews concerning:

respiratory interventions;
inspiratory muscle training;
recovery modalities;

Pg. 3 - Inclusion criteria are presented twice. Please remove the duplicated paragraph.

Pg. 3 - Table 1 should also include: p-values between groups; standardized effect sizes. This allows readers to verify baseline comparability.

Pg. 4 - The intervention is inconsistently described as occurring: before training and after training. Please ensure consistency throughout the manuscript.

Pg. 5-Testing standardization could be improved. Please specify:

caffeine restrictions;
sleep requirements;
menstrual cycle control;
hydration monitoring.

Pg. 6-Pulmonary function testing should explicitly report adherence to the latest ATS/ERS spirometry standards.

Pg. 7-The equation used to estimate VO₂max from the Yo-Yo IRT1 should be accompanied by the original reference.

Pg. 8-Please report:

confidence intervals;
mean differences;
standardized effect sizes for pairwise comparisons.

These are strongly encouraged by Life.

Pg. 8-The interpretation of partial eta squared should follow current recommendations. The thresholds used are unusual and should be justified or replaced by more widely accepted criteria.

Pg. 9–12-Several figures duplicate the information already presented in Table 6. Consider combining figures or presenting interaction plots instead.

Pg. 12–15 (Discussion)- The Discussion would benefit from comparison with:

inspiratory muscle training literature;
respiratory muscle training in football;
recovery interventions.

Currently, comparisons rely almost exclusively on previous halotherapy studies.

Pg. 15-Practical implications should clearly state:

which athletes
which training phases
which frequency
are most likely to benefit from halotherapy.

Pg. 16-The conclusions should be slightly more cautious. Instead of: "halotherapy can be integrated into training programmes..." consider "halotherapy may represent a promising complementary strategy, although confirmation in larger multicentre randomized trials is still required."

Several references are relatively old considering the rapid evolution of respiratory interventions. Please update the bibliography with additional studies published during the last five years whenever possible.

Comments on the Quality of English Language The manuscript is generally well written and understandable. However, the English language would benefit from careful revision by a native English speaker or a professional editing service. Several sentences are unnecessarily long, some expressions are repetitive, and minor grammatical and stylistic inconsistencies reduce the overall readability. Improving sentence structure, terminology consistency, and scientific writing style would enhance the clarity and impact of the manuscript without altering its scientific content.

Author Response

Reviewer 1

Q1. Study design and internal validity

Pg. 3–4 (Lines 99–149)- Although the study is presented as a randomized controlled trial, important methodological details remain insufficiently described.

Because halotherapy is susceptible to placebo effects, the absence of a sham-halotherapy control group should be discussed as an important limitation.

A1: Thank you for this valuable comment. We agree that additional methodological details improve the transparency and internal validity of the study. Accordingly, the Methods section has been substantially revised to provide detailed information regarding the random sequence generation procedure, allocation concealment, personnel responsible for randomization, and blinding procedures. Because the intervention required participants to attend halotherapy sessions, participant blinding was not feasible. This has now been explicitly acknowledged. Furthermore, as suggested, we have expanded the Limitations section to discuss the absence of a sham-halotherapy control group as an important methodological limitation. We acknowledge that expectancy and placebo effects cannot be completely excluded, and we now recommend that future randomized controlled trials incorporate sham-halotherapy conditions to better isolate the specific physiological effects of halotherapy.

Q2. Training load control

Pg. 4–5 (Lines 139–200) The training programme is only briefly described. Please provide:

weekly external load;
internal load (RPE or HR);
progression across the 12 weeks;
confirmation that both groups completed identical training loads.

Otherwise, differences may reflect unequal training exposure rather than halotherapy.

A2: We sincerely thank the Reviewer for this valuable and constructive comment. We agree that a more comprehensive description of the training load is essential to strengthen the internal validity of the study and to ensure that the observed effects can be attributed to the halotherapy intervention rather than differences in training exposure.

Accordingly, the Methods section has been substantially revised. We have clarified that both groups completed the same preseason football training programme, supervised by the same coaching staff, following an identical schedule, training content, session duration, weekly frequency, and progression throughout the 12-week intervention period. The only difference between groups was the addition of halotherapy sessions in the intervention group.

We have also added a detailed description of internal training load monitoring. Training intensity was monitored throughout the intervention using the session Rating of Perceived Exertion (sRPE) method based on the Borg CR-10 scale. Players reported their perceived exertion approximately 30 minutes after each training session, and the target training intensity was maintained within a range of 5–7 AU, corresponding to moderate-to-vigorous exercise intensity. This procedure was applied consistently to both groups.

Furthermore, a new table has been included to illustrate the progressive structure of the 12-week preseason training programme, including the primary training objectives and target intensity across each training phase.

We believe these additions substantially improve the transparency of the intervention and confirm that both groups were exposed to equivalent football training loads throughout the study, thereby reducing the likelihood that the observed between-group differences were attributable to unequal training exposure rather than the halotherapy intervention.

Phyiological mechanisms remain speculative

Pg. 14–15 (Lines 474–501) - The discussion proposes several physiological mechanisms involving:

mucociliary clearance;
oxygen extraction;
mitochondrial adaptations;
respiratory efficiency.

However, none of these variables were measured.

The discussion should clearly distinguish between: measured outcomes; hypotheses; and speculative mechanisms. Statements suggesting causal physiological mechanisms should be substantially moderated.

A3: We sincerely thank the Reviewer for this insightful comment. We fully agree that the Discussion should clearly differentiate between the outcomes directly measured in the present study and the physiological mechanisms proposed on the basis of previous literature.

Accordingly, we have carefully revised the Discussion to avoid causal interpretations that are not directly supported by our data. Statements describing potential mechanisms, including mucociliary clearance, improved oxygen extraction, mitochondrial adaptations, and enhanced respiratory efficiency, have been rephrased as possible explanations rather than established effects. Throughout the revised manuscript, terminology such as may, might, could, and has been proposed has been used to emphasize the hypothetical nature of these mechanisms.

Furthermore, we now explicitly acknowledge that the present study did not assess inflammatory biomarkers, mucociliary function, respiratory muscle activation, oxygen extraction, mitochondrial adaptations, or other mechanistic variables. Consequently, these physiological pathways should be interpreted as hypotheses derived from previous literature rather than direct findings of the current study.

Finally, we have expanded the Limitations and Future Research sections to recommend that future randomized controlled trials incorporate biochemical, physiological, and cellular assessments to clarify the mechanisms underlying the observed improvements in respiratory and aerobic performance.

Clinical significance

Pg. 8–12 - Statistical significance is consistently reported. However, the manuscript does not adequately discuss:

minimal clinically important differences;
practical significance;
whether observed improvements translate into meaningful football performance.

Please strengthen the interpretation of practical relevance.

A4: We sincerely thank the Reviewer for this thoughtful suggestion. We agree that, beyond statistical significance, the practical relevance of the observed improvements should be more clearly discussed.

Accordingly, we have substantially expanded the Discussion to better interpret the clinical and practical implications of our findings. Specifically, we now discuss how improvements in respiratory muscle strength, pulmonary function, aerobic capacity, and Yo-Yo IRT1 performance may translate into enhanced football-specific performance, including improved tolerance to repeated high-intensity efforts, faster recovery between intense actions, and the maintenance of performance during prolonged match play.

In addition, we have clarified that universally accepted minimal clinically important difference (MCID) values have not been established for respiratory muscle strength, pulmonary function, or Yo-Yo IRT1 performance in elite female soccer players. Therefore, the practical interpretation of our findings has been based on their magnitude, effect sizes, and their established relationships with football-specific performance reported in previous literature, rather than formal MCID thresholds.

We believe these revisions provide a more balanced interpretation of the practical significance of the intervention while avoiding overstatement of the findings.

Generalizability

Pg. 15 (Limitations)-Although the authors mention some limitations, they underestimate their impact. The manuscript should further discuss:

single-club sample;
elite Turkish female players only;
preseason period only;
absence of long-term follow-up.

Generalization should therefore be more conservative.

A5: We sincerely thank the Reviewer for this valuable comment. We agree that the external validity of our findings should be interpreted more cautiously.

Accordingly, we have substantially expanded the Limitations section to provide a more comprehensive discussion of the study's generalizability. Specifically, we now acknowledge that the study was conducted in players from a single professional women's football club, which may limit the applicability of the findings to teams with different training environments or organizational structures. We also clarify that the sample consisted exclusively of elite Turkish female football players, and therefore the results should not be generalized to male athletes, youth players, recreational athletes, or populations from different competitive levels or countries without further investigation.

Furthermore, we now emphasize that the intervention was performed exclusively during the preseason period, and the effectiveness of halotherapy during the competitive season remains unknown. Finally, we acknowledge the absence of long-term follow-up, which precludes conclusions regarding the persistence of the observed physiological adaptations after the intervention.

In addition, the Conclusion has been revised to adopt a more conservative interpretation of the findings and to emphasize the need for larger multicentre randomized controlled trials with more diverse populations and longer follow-up periods before broad generalizations can be made.

CONSORT reporting

Although CONSORT is mentioned, several reporting items remain incomplete.

Please verify compliance with:

participant flow;
allocation concealment;
implementation;
blinding;
protocol deviations.

A6:We sincerely thank the Reviewer for this valuable observation. Following the Reviewer's suggestions, we carefully re-evaluated the manuscript in accordance with the CONSORT 2010 Statement and revised the manuscript to improve reporting transparency and completeness.

Specifically:

Participant flow has been clarified, and the CONSORT flow diagram was reviewed to ensure that participant enrolment, randomization, follow-up, and analysis are completely and consistently reported.
Allocation concealment has now been described in detail within the Methods section, including the allocation concealment procedure and the personnel responsible for implementing the randomization process.
Implementation has been clarified by specifying who generated the random allocation sequence, who enrolled participants, and who assigned participants to the intervention groups.
Blinding procedures have been explicitly reported. Because of the nature of the intervention, participant blinding was not feasible; this has now been clearly acknowledged. Outcome assessor blinding (or the absence thereof) has also been explicitly described and justified.
Protocol deviations have been clarified. Attendance and compliance with both the football training programme and halotherapy sessions were monitored throughout the intervention, and no major protocol deviations affecting the final analyses occurred. This information has now been included in the revised manuscript.

We believe these revisions substantially improve the manuscript's compliance with the CONSORT reporting guidelines and enhance the transparency and reproducibility of the study.

Minor Comments

Q1: Pg. 2 (Introduction)-The Introduction would benefit from a more critical review of previous evidence.

Include recent systematic reviews concerning:

respiratory interventions;
inspiratory muscle training;
recovery modalities;

A1: We sincerely thank the Reviewer for this valuable suggestion. We agree that a more comprehensive and critical synthesis of the existing literature strengthens the scientific rationale for the present study. Accordingly, the Introduction has been substantially revised to incorporate recent systematic reviews and meta-analyses addressing respiratory interventions, inspiratory muscle training (IMT), and recovery modalities in athletic populations. Rather than simply summarizing previous findings, we now critically discuss the consistency and limitations of the available evidence, highlighting that although respiratory interventions—particularly IMT—have demonstrated beneficial effects on respiratory muscle strength and exercise performance, their effects on pulmonary function and football-specific performance remain inconsistent. Furthermore, we compare the current evidence supporting established recovery strategies with the relatively limited evidence available for halotherapy, thereby emphasizing the existing knowledge gap and providing a stronger rationale for the present randomized controlled trial. These revisions strengthen the scientific background of the study and more clearly justify the need for investigating halotherapy in elite female football players.

Q2: Pg. 3 - Inclusion criteria are presented twice. Please remove the duplicated paragraph.

A2: We appreciate the Reviewer's careful reading of the manuscript. The duplicated paragraph describing the inclusion criteria has been deleted, and the corresponding section has been revised to improve readability and conciseness.

Q3: Pg. 3 - Table 1 should also include: p-values between groups; standardized effect sizes. This allows readers to verify baseline comparability.

A3: We sincerely thank the Reviewer for this valuable suggestion. In response, between-group p-values for all baseline characteristics have been calculated and added to Table 1 to facilitate the assessment of baseline comparability between the intervention and control groups. These additions improve the transparency of the baseline comparisons and allow readers to verify that no statistically significant differences existed between groups before the intervention.

Q4: Pg. 4 - The intervention is inconsistently described as occurring: before training and after training. Please ensure consistency throughout the manuscript.

A4: We sincerely thank the Reviewer for identifying this inconsistency. The discrepancy resulted from an editing oversight. The manuscript has been carefully revised, and the intervention is now consistently described as being performed before the scheduled football training sessions throughout the manuscript.

Q5: Pg. 5. Testing standardization could be improved. Please specify:

caffeine restrictions;
sleep requirements;
menstrual cycle control;
hydration monitoring.

A5: We sincerely thank the Reviewer for this valuable suggestion. In response, we have expanded the Methods section to provide additional details regarding the standardization of testing conditions. Specifically, participants were instructed to refrain from caffeine consumption before testing, obtain a normal night's sleep, and maintain their usual hydration status prior to each assessment. All measurements were performed under standardized conditions and at approximately the same time of day.

We acknowledge that menstrual cycle phase was not controlled or recorded during the study. This has now been explicitly stated in the Limitations section, and we recognize that hormonal fluctuations may have influenced some physiological responses.

Q6: Pg. 6-Pulmonary function testing should explicitly report adherence to the latest ATS/ERS spirometry standards.

A6: We sincerely thank the Reviewer for this valuable suggestion. In response, we have revised the Methods section to explicitly state that pulmonary function testing was performed in accordance with the latest American Thoracic Society/European Respiratory Society (ATS/ERS) Technical Standard for Spirometry. Additional details regarding the standardized testing procedures, including acceptability and repeatability criteria, have also been incorporated to improve methodological transparency.

Q7:Pg. 7-The equation used to estimate VO₂max from the Yo-Yo IRT1 should be accompanied by the original reference.

A7: We sincerely thank the Reviewer for this helpful suggestion. In response, we have added the original reference describing the prediction equation used to estimate VO₂max from the Yo-Yo Intermittent Recovery Test Level 1 (Yo-Yo IRT1). The corresponding citation has been incorporated into the Methods section immediately following the equation to improve transparency and facilitate reproducibility.

Q8: Pg. 8-Please report:

confidence intervals;
mean differences;
standardized effect sizes for pairwise comparisons.

These are strongly encouraged by Life.

A8: We sincerely thank the Reviewer for this valuable suggestion. In response, we have expanded the statistical reporting in accordance with the recommendations of Life. Specifically, mean differences, 95% confidence intervals (95% CIs), and standardized effect sizes for pairwise comparisons have now been calculated and incorporated into the Results section and the corresponding tables, where appropriate. These additions provide a more comprehensive interpretation of the magnitude, precision, and practical relevance of the observed effects, thereby improving the transparency and interpretability of our findings.

Q9:Pg. 8. The interpretation of partial eta squared should follow current recommendations. The thresholds used are unusual and should be justified or replaced by more widely accepted criteria.

A9: We thank the Reviewer for this helpful observation. The thresholds used in the manuscript correspond to the widely accepted criteria proposed by Cohen. To improve clarity, we have now explicitly cited the original methodological reference in the Statistical Analysis section and clarified that the interpretation of ηp² values was based on these established recommendations.

Q10: Pg. 9–12: Several figures duplicate the information already presented in Table 6. Consider combining figures or presenting interaction plots instead.

A10: We appreciate the Reviewer's comment. The figures were retained because they provide a visual representation of the temporal changes and group × time interaction effects, whereas Table 6 presents the detailed numerical values. Nevertheless, to reduce redundancy, the figures have been revised and simplified.

Q11:Pg. 12–15 (Discussion)- The Discussion would benefit from comparison with:

inspiratory muscle training literature;
respiratory muscle training in football;
recovery interventions.

Currently, comparisons rely almost exclusively on previous halotherapy studies.

A11: We sincerely thank the Reviewer for this thoughtful suggestion. We agree that comparisons with related respiratory interventions may provide additional context for interpreting our findings. However, we respectfully note that the primary objective of the present study was to evaluate the effects of halotherapy, rather than inspiratory or respiratory muscle training. As halotherapy and inspiratory muscle training differ substantially in their underlying mechanisms, intervention protocols, and therapeutic targets, we considered that the Discussion should primarily focus on studies investigating halotherapy to maintain the specificity and coherence of the interpretation.

Nevertheless, in response to the Reviewer's recommendation, we have incorporated a brief discussion of the evidence from inspiratory muscle training and respiratory intervention studies to place our findings within the broader context of respiratory performance enhancement in athletes. We have also emphasized that, although these interventions may produce similar improvements in some respiratory outcomes, they represent distinct therapeutic approaches and therefore direct comparisons should be interpreted with caution.We believe this revision provides a broader scientific context while preserving the primary focus of the manuscript on halotherapy.

Q12: Pg. 15. Practical implications should clearly state:

which athletes
which training phases
which frequency
are most likely to benefit from halotherapy.

A12: We sincerely thank the Reviewer for this valuable suggestion. In response, we have expanded the Practical Implications section to provide more specific guidance regarding the potential application of halotherapy. The revised text now clearly states that the findings are applicable to elite female football players, that the intervention was implemented during the preseason period, and that halotherapy was administered three times per week for 12 weeks before scheduled football training sessions. We also emphasize that these recommendations are limited to the population and training context investigated in the present study and should not be generalized to other athletic populations without further evidence.

Q13:Pg. 16-The conclusions should be slightly more cautious. Instead of: "halotherapy can be integrated into training programmes..." consider "halotherapy may represent a promising complementary strategy, although confirmation in larger multicentre randomized trials is still required."

A13: We sincerely thank the Reviewer for this valuable suggestion. We agree that a more cautious interpretation of the findings is appropriate. Accordingly, the Conclusion has been revised to avoid definitive statements regarding the implementation of halotherapy. The revised conclusion now states that halotherapy may represent a promising complementary strategy for elite female football players during the preseason while emphasizing that the findings require confirmation through larger multicentre randomized controlled trials before broader recommendations can be made.

Q14:Several references are relatively old considering the rapid evolution of respiratory interventions. Please update the bibliography with additional studies published during the last five years whenever possible.

A14: We sincerely thank the Reviewer for this helpful suggestion. In response, we have carefully reviewed and updated the bibliography by incorporating additional recent studies, including systematic reviews and original research articles published within the last five years, where appropriate. These newly added references strengthen the scientific background of the Introduction and Discussion and ensure that the manuscript better reflects the current state of knowledge regarding respiratory interventions, inspiratory muscle training, recovery strategies, and halotherapy.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Dear Authors

As one of the reviewers, I express my personal scientific opinion on your work. I want to reassure you that I was trying to be as positive, constructive, fair, and honest as possible in my assessment of your work. First of all, well done for the time spent to accomplish the project. The logical flow in the introduction, the presentation of ICC and CV, the calculation of the Effect Size, and the presentation of the limitations are all positive points. However, some methodological points require further clarification; the presentation of the results needs improvement; and an efficient rewriting /restructuring of the discussion section is required. Please accept my judgment positively and constructively.

General comments:

On several occasions, there are repetitions throughout the manuscript. Please eliminate repetitions.
Could you please check syntax and grammar throughout the manuscript for clarity?
You have categorized your sample as elite female football players. Looking at the VO2max results of your groups carefully (pre- and post-preseason training), are you positive that this sample should be categorized at an elite level? Please see also my comment number 16 below.
The Discussion section needs a massive restructuring.

Introduction:

Although the introduction has a good and logical flow, considering that some other studies have already examined or reviewed the effect of halotherapy on exercise performance, my concern is why you chose to evaluate only female participants? Is there any specific difference in physiological/biological responses to halotherapy between males and females? A background argument is required on this.

Methods:

Table 1, 3^rd column: I am positive that you wanted to report “Experimental” and not “variables”.
The baseline VO2max values of both groups should be presented in Table 1.
Lines 107-122: There are two identical paragraphs; One should be eliminated.
Line 125: How did you perform the randomization of the groups?
Lines 124-136: Within these lines, there are repetitions on several occasions. Please avoid repetitions.
Table 4, column 3 from left: Instead of reporting 2^nd, 3^rd, 4^th, etc., please consider reporting “from 2^nd to 13^th week”.
Why did you not control ergogenic aid supplements and diet at least 48 h before each official evaluation?
Why did you not control caffeine consumption before each testing?
Why did you not measure (pre- and post-treatment) body fat percentage, instead of evaluating only body mass?

Results

This is a crucial point. All figures should be redesigned; otherwise, they produce confusion. Please keep compatibility in values of the Y axes when presenting the same variable of both groups (pre- vs post-) in the same figure.
Figure 4: Considering the VO2max values in female soccer by competition level (i.e., Elite/Professional: 49-58 mL⋅kg⁻¹⋅min⁻¹; Collegiate/Division I: 48-54 mL⋅kg⁻¹⋅min⁻¹; Amateur/Lower Divisions: 43-50 mL⋅kg⁻¹⋅min⁻¹, Recreational: 38-42 mL ⋅ kg⁻¹ ⋅ min⁻¹, I found your VO2max results (pre- ~24.5 vs post- ~25.5 in control and ~33 in halotherapy group) extremely low. Based on the existing literature in female soccer, your results are even lower than the recreational level. How do you explain this?
Lines 42-43 and 383-385: You are reporting contradictory findings of the same variable, FVC, which, based on your results, increased over time in both groups (p< 0.001) due to preseason training. So, in the abstract (and in Table 6), you clearly reported no difference in FVC between the groups (Group x Time Interaction; F= 370, p= 0.141), BUT in lines 383-385 you claimed that halotherapy treatment improved FVC. What did you finally observe for FVC?

Discussion/Conclusion:

Lines 391-397: “Reviewing the existing literature on … and peak expiratory flow”. This paragraph should be moved to the Introduction section. Please avoid reviewing the literature in the Discussion section and just discuss your results.
Lines 392-394 and 398-401: Please avoid repetition as well as reviewing the literature in this section.
Lines 401-437: The same as comments 18 and 19 above. All this background information should be moved to the Introduction section, and in the Discussion you should just discuss the results.
Lines 448-456: You have attributed the improvement in the yo-yo test and VO2max as observed in the halotherapy group to increases in lung function and respiratory parameters, such as FEV and FVC. However, based on your results (lines 42-43 and Table 6), FVC was not different between the control and halotherapy groups. This is quite confusing. So, how can you claim this attribution?
In addition, how can you physiologically explain that you have observed significant group × time interactions for MIP, MEP, VO₂max, FEV₁, PEF, and MVV but not for FVC (forced vital capacity)? Please discuss.
Taking also into consideration comment 16, would you expect similar results if female players with much higher aerobic capacity were evaluated?
Would you expect different results if male players (elite or amateurs) were evaluated? And if yes, why?
Are you positive that your results could be generalized to all levels of female soccer?

Comments on the Quality of English Language

The English could be improved to more clearly express the research. Please specifically check syntax and grammar throughout the manuscript for clarity.

Author Response

Reviewer 2

Dear Authors

General comments:

On several occasions, there are repetitions throughout the manuscript. Please eliminate repetitions.

A1: We sincerely thank the Reviewer for this helpful observation. The manuscript has been carefully revised to eliminate repetitive statements throughout the Introduction, Methods, Discussion, and Conclusion. Redundant descriptions have been removed or consolidated to improve clarity, readability, and the overall flow of the manuscript.

Could you please check syntax and grammar throughout the manuscript for clarity?

A2: We sincerely thank the Reviewer for this suggestion. The entire manuscript has been carefully proofread and edited to improve grammar, syntax, sentence structure, and overall readability. We believe these revisions have enhanced the clarity and fluency of the manuscript.

You have categorized your sample as elite female football players. Looking at the VO2max results of your groups carefully (pre- and post-preseason training), are you positive that this sample should be categorized at an elite level? Please see also my comment number 16 below.

A3: We sincerely thank the Reviewer for raising this important point. We acknowledge that the classification of athletic level should not rely solely on physiological variables such as VO₂max. Accordingly, we have clarified the criteria used to define the participants as elite female football players. Specifically, the classification was based on their competitive status, participation in the highest national league, professional training environment, and regular involvement in structured football programmes, rather than on VO₂max values alone. This clarification has been added to the Methods section.

The Discussion section needs a massive restructuring.

A4: We sincerely thank the Reviewer for this valuable comment. In response, the Discussion section has been comprehensively revised and restructured to improve its scientific coherence and critical interpretation. Specifically, we have moderated speculative mechanistic explanations, incorporated comparisons with recent literature where appropriate, strengthened the discussion of practical and clinical relevance, expanded the limitations, and adopted a more balanced interpretation of the findings. We believe these revisions have substantially improved the overall quality, organization, and readability of the Discussion section.

Introduction:

Although the introduction has a good and logical flow, considering that some other studies have already examined or reviewed the effect of halotherapy on exercise performance, my concern is why you chose to evaluate only female participants? Is there any specific difference in physiological/biological responses to halotherapy between males and females? A background argument is required on this.

A5: We sincerely thank the Reviewer for this insightful comment. We agree that the rationale for focusing specifically on female athletes should be more clearly articulated. In response, we have expanded the Introduction to explain that female athletes remain underrepresented in the literature on respiratory interventions and halotherapy, with most previous studies involving male or mixed-sex populations. We also note that female athletes differ from males in several physiological characteristics relevant to respiratory function and exercise performance, including pulmonary dimensions, ventilatory responses, hormonal profiles, and aerobic adaptations. Although there is currently no direct evidence demonstrating sex-specific responses to halotherapy, these physiological differences highlight the importance of investigating the intervention in female athletes rather than assuming that findings from male populations are directly applicable. Accordingly, we have strengthened the scientific rationale for conducting the present study exclusively in elite female football players and have identified this as an important gap in the existing literature.

Methods:

Table 1, 3^rd column: I am positive that you wanted to report “Experimental” and not “variables”.

A6: We appreciate the Reviewer's careful observation. The labeling error in the third column of Table 1 has been corrected. The column heading has been revised to "Halotherapy Group" to accurately identify the intervention group and improve the clarity of the table.

The baseline VO2max values of both groups should be presented in Table 1.

A7: We sincerely thank the Reviewer for this helpful comment. Accordingly, Table 1 has been revised to include the baseline VO₂max values for both study groups as an additional row. Furthermore, the corresponding between-group p-value has been calculated and reported to facilitate the assessment of baseline equivalence. This revision enhances the completeness of the baseline characteristics and improves the transparency of the study reporting.

Lines 107-122: There are two identical paragraphs; One should be eliminated.

A8: We appreciate the Reviewer's careful reading of the manuscript. The duplicated paragraph describing the inclusion criteria has been deleted, and the Methods section has been revised accordingly to improve conciseness and avoid unnecessary repetition.

Line 125: How did you perform the randomization of the groups?

A9: We sincerely thank the Reviewer for raising this important methodological point. In response, we have substantially expanded the Methods section to provide a detailed description of the randomization procedure. Specifically, we now describe the method of sequence generation, allocation concealment, the investigator responsible for the randomization process, and the implementation of participant allocation in accordance with the CONSORT recommendations. These additions improve the transparency and reproducibility of the study design.

Lines 124-136: Within these lines, there are repetitions on several occasions. Please avoid repetitions.

A10: We appreciate the Reviewer's careful reading of the manuscript. The section corresponding to Lines 124–136 has been thoroughly revised to remove repetitive descriptions, consolidate overlapping information, and improve the logical flow of the text. These revisions enhance the clarity and readability of the Methods section without altering the methodological content.

Table 4, column 3 from left: Instead of reporting 2^nd, 3^rd, 4^th, etc., please consider reporting “from 2^nd to 13^th week”.

A11: We appreciate the Reviewer's valuable suggestion. Accordingly, the wording in the third column of Table 4 has been revised from individual weekly labels to "from 2nd to 13th week", as recommended. This modification improves the clarity and consistency of the intervention schedule presented in the table.

Why did you not control ergogenic aid supplements and diet at least 48 h before each official evaluation?

A12: We sincerely thank the Reviewer for this important methodological comment. In response, we have revised the Methods section to provide additional details regarding the standardization of the pre-testing procedures. Participants were instructed to refrain from consuming caffeine-containing products before each assessment, maintain their usual dietary habits and hydration status, and obtain a normal night's sleep prior to testing. All evaluations were performed under standardized conditions and at approximately the same time of day to minimize potential sources of variability. We acknowledge that the intake of ergogenic supplements and dietary intake during the 48 h preceding each assessment was not formally monitored or recorded, and this has now been explicitly acknowledged as a limitation of the study. We agree that future randomized controlled trials should include stricter dietary and supplement control to further enhance methodological rigor.

Why did you not control caffeine consumption before each testing?

A13: We sincerely thank the Reviewer for this important methodological comment. In response, we have revised the Methods section to provide additional details regarding the standardization of the pre-testing procedures. Participants were instructed to refrain from consuming caffeine-containing products before each assessment, maintain their usual dietary habits and hydration status, and obtain a normal night's sleep prior to testing. All evaluations were performed under standardized conditions and at approximately the same time of day to minimize potential sources of variability.

We acknowledge that the intake of ergogenic supplements and dietary intake during the 48 h preceding each assessment was not formally monitored or recorded, and this has now been explicitly acknowledged as a limitation of the study. We agree that future randomized controlled trials should include stricter dietary and supplement control to further enhance methodological rigor.

Why did you not measure (pre- and post-treatment) body fat percentage, instead of evaluating only body mass?

A14: We sincerely thank the Reviewer for this thoughtful comment. We agree that body composition, including body fat percentage, could provide additional information regarding the physiological adaptations associated with the intervention. However, the primary objective of the present randomized controlled trial was to investigate the effects of halotherapy on respiratory muscle strength, pulmonary function, aerobic capacity, and football-specific performance, rather than changes in body composition. Accordingly, body mass was recorded as a general anthropometric characteristic, whereas body fat percentage was not included as an outcome measure in the study protocol. We acknowledge that the inclusion of body composition assessments would have provided additional insight and have therefore recognized this as a limitation of the study. Future investigations should consider incorporating validated body composition measurements to further explore the potential effects of halotherapy on body composition in athletes.

Results

This is a crucial point. All figures should be redesigned; otherwise, they produce confusion. Please keep compatibility in values of the Y axes when presenting the same variable of both groups (pre- vs post-) in the same figure.

We sincerely thank the Reviewer for this valuable suggestion. The figures were generated using GraphPad Prism 10, which automatically scales the y-axes according to the data range of each graph to optimize visualization. We acknowledge that using identical y-axis scales may facilitate direct visual comparison between groups. However, because the numerical values and statistical comparisons are comprehensively presented in the corresponding tables, we believe that the current graphical presentation does not affect the interpretation of the results. Nevertheless, we have carefully reviewed all figures to improve their clarity and consistency wherever possible.

Figure 4: Considering the VO2max values in female soccer by competition level (i.e., Elite/Professional: 49-58 mL⋅kg⁻¹⋅min⁻¹; Collegiate/Division I: 48-54 mL⋅kg⁻¹⋅min⁻¹; Amateur/Lower Divisions: 43-50 mL⋅kg⁻¹⋅min⁻¹, Recreational: 38-42 mL ⋅ kg⁻¹ ⋅ min⁻¹, I found your VO2max results (pre- ~24.5 vs post- ~25.5 in control and ~33 in halotherapy group) extremely low. Based on the existing literature in female soccer, your results are even lower than the recreational level. How do you explain this?

A16: We sincerely thank the Reviewer for this careful observation and for identifying this important inconsistency. Following your comment, we conducted a comprehensive re-examination of the original dataset, statistical outputs, and all tables and figures related to VO₂max. During this verification process, we identified that the VO₂max values had been incorrectly transferred into the manuscript during the preparation of the tables and figures. Importantly, this was a reporting error that occurred during manuscript preparation and did not originate from the original data collection or statistical analyses.

The VO₂max values have now been corrected throughout the entire manuscript, including Table 7, Figure 4, the Results, Discussion, Abstract, and Conclusion wherever applicable. The corrected baseline values (Halotherapy Group: 47.45 ± 0.96 mL·kg⁻¹·min⁻¹; Control Group: 47.39 ± 1.69 mL·kg⁻¹·min⁻¹) are consistent with the expected aerobic fitness levels reported for elite female football players and closely align with the reference ranges cited by the Reviewer.

To ensure the accuracy of the revised manuscript, all VO₂max-related analyses, tables, figures, and corresponding interpretations were carefully rechecked against the original statistical outputs. We sincerely appreciate the Reviewer's careful evaluation, which helped us identify and correct this reporting error.

Lines 42-43 and 383-385: You are reporting contradictory findings of the same variable, FVC, which, based on your results, increased over time in both groups (p< 0.001) due to preseason training. So, in the abstract (and in Table 6), you clearly reported no difference in FVC between the groups (Group x Time Interaction; F= 370, p= 0.141), BUT in lines 383-385 you claimed that halotherapy treatment improved FVC. What did you finally observe for FVC?

A17: We sincerely thank the Reviewer for this careful observation. We agree that the original wording was inconsistent with the statistical results and may have led to an incorrect interpretation. Following the Reviewer's comment, we carefully re-evaluated the corresponding sections of the manuscript. The Results indicate that FVC increased over time in both groups (significant time effect), whereas the Group × Time interaction was not statistically significant. Therefore, the observed improvement in FVC cannot be specifically attributed to halotherapy.

Accordingly, the statements in the Abstract, Results, Discussion, and Conclusion have been revised to ensure complete consistency with the statistical findings. The revised manuscript now clearly states that the increase in FVC was observed in both groups, most likely reflecting the effects of the preseason training programme, while halotherapy did not demonstrate an additional significant effect on FVC compared with the control group. Changes made: Abstract, Results, Discussion, Conclusion, Table 6, and corresponding text throughout the manuscript.

Discussion/Conclusion:

Lines 391-397: “Reviewing the existing literature on … and peak expiratory flow”. This paragraph should be moved to the Introduction section. Please avoid reviewing the literature in the Discussion section and just discuss your results.

A18: We sincerely thank the Reviewer for this valuable suggestion. We agree that a general overview of the existing literature is more appropriately presented in the Introduction than in the Discussion. Accordingly, the paragraph previously located in Lines 391–397 has been removed from the Discussion section and incorporated into the Introduction, where it provides additional background and context for the study. The Discussion has been revised to focus more specifically on the interpretation of the present findings in relation to the existing literature, thereby improving its scientific coherence and organization.

Lines 392-394 and 398-401: Please avoid repetition as well as reviewing the literature in this section.

A19: We sincerely thank the Reviewer for this valuable comment. In response, the paragraph previously located in Lines 392–394, which contained a general review of the literature, has been removed from the Discussion section and incorporated into the Introduction, where it is more appropriately presented. Consequently, the repetitive content between Lines 392–394 and 398–401 has been eliminated. The revised Discussion now focuses on the interpretation of the present findings in relation to the existing literature, thereby improving its clarity, conciseness, and overall scientific coherence.

Lines 401-437: The same as comments 18 and 19 above. All this background information should be moved to the Introduction section, and in the Discussion, you should just discuss the results.

A20: We sincerely thank the Reviewer for this constructive suggestion. In response, the Discussion section has been comprehensively revised and restructured. The background information previously presented in Lines 401–437 has been removed from the Discussion, with the relevant contextual information incorporated into the Introduction, where appropriate. Consequently, the Discussion now focuses primarily on the interpretation of the present findings, comparison with relevant previous studies, and their practical implications, thereby improving its scientific coherence, conciseness, and overall readability.

Lines 448-456: You have attributed the improvement in the yo-yo test and VO2max as observed in the halotherapy group to increases in lung function and respiratory parameters, such as FEV and FVC. However, based on your results (lines 42-43 and Table 6), FVC was not different between the control and halotherapy groups. This is quite confusing. So, how can you claim this attribution?

A21: We sincerely thank the Reviewer for this important observation. We agree that the original wording could be interpreted as attributing the improvements in Yo-Yo IRT1 performance and estimated VO₂max to changes in FVC, despite the absence of a significant Group × Time interaction for this variable. In response, we have carefully revised the corresponding paragraph to ensure consistency with the statistical findings. Specifically, FVC has been removed from the interpretation, and the discussion now focuses on the respiratory variables that demonstrated improvements consistent with the intervention, including FEV₁, MVV, PEF, MIP, and MEP. Furthermore, we have adopted more cautious language by stating that the observed improvements in exercise performance may have been associated with enhanced respiratory efficiency rather than implying a direct causal relationship. This revision ensures that the interpretation accurately reflects the measured outcomes and avoids overstating the effects of halotherapy.

In addition, how can you physiologically explain that you have observed significant group × time interactions for MIP, MEP, VO₂max, FEV₁, PEF, and MVV but not for FVC (forced vital capacity)? Please discuss.

A22: We sincerely thank the Reviewer for this insightful comment. We agree that the different responses observed among the respiratory variables warrant further physiological interpretation. In response, we have expanded the Discussion to clarify that FVC primarily reflects static lung volume, which is largely determined by anatomical characteristics and is generally less responsive to short-term interventions in healthy, well-trained athletes. In contrast, FEV₁, PEF, MVV, MIP, and MEP are functional measures of respiratory muscle performance, ventilatory capacity, and expiratory airflow, making them more sensitive to improvements in respiratory efficiency. Therefore, the absence of a significant Group × Time interaction for FVC does not contradict the improvements observed in the other respiratory parameters but rather suggests that the intervention may have preferentially influenced functional respiratory performance rather than static lung volume. The Discussion has been revised accordingly to provide a clearer physiological interpretation consistent with the study findings.

Taking also into consideration comment 16, would you expect similar results if female players with much higher aerobic capacity were evaluated?

A23: We sincerely thank the Reviewer for this thoughtful comment. As explained in our response to Comment 16, a detailed verification of the original dataset and statistical outputs revealed that the VO₂max values had been incorrectly transferred into the manuscript during table preparation. This reporting error has now been corrected throughout the manuscript, including the tables, figures, and all relevant text.

The corrected baseline VO₂max values (Halotherapy Group: 47.45 ± 0.96 mL·kg⁻¹·min⁻¹; Control Group: 47.39 ± 1.69 mL·kg⁻¹·min⁻¹) are consistent with those reported for elite female football players in the literature and closely align with the reference values cited by the Reviewer. Therefore, we believe that the participants were appropriately classified as elite athletes, and the interpretation of the findings is consistent with this competitive level.

Nevertheless, we acknowledge that responses to halotherapy may vary according to athletes' physiological characteristics and competitive standards. Accordingly, we have adopted a more cautious interpretation of our findings and highlighted that future studies should investigate whether similar effects are observed in athletes with different performance profiles and aerobic capacities.

Changes made: Table 7, Figure 4, Abstract, Results, Discussion, and Conclusion.

Would you expect different results if male players (elite or amateurs) were evaluated? And if yes, why?

A24: We sincerely thank the Reviewer for this insightful comment. The present study was specifically designed to investigate the effects of halotherapy in elite female football players, and therefore our findings should be interpreted within this population only. Although male and female athletes differ in several physiological characteristics relevant to respiratory function and exercise performance, including lung size, respiratory muscle strength, hormonal profiles, and aerobic capacity, there is currently no robust evidence demonstrating that responses to halotherapy differ according to sex.

Consequently, we cannot conclude whether male athletes, either elite or amateur, would exhibit similar or different responses to the intervention. To reflect this important consideration, we have strengthened the Limitations and Future Research sections by emphasizing that further randomized controlled studies including both male and female athletes are needed to determine whether sex and competitive level influence the physiological and performance-related effects of halotherapy.

Are you positive that your results could be generalized to all levels of female soccer?

A25: We sincerely thank the Reviewer for this important comment. We agree that the findings of the present study should not be generalized to all levels of female football. The study was conducted exclusively in elite Turkish female football players from a single club during the preseason period, and therefore the results should be interpreted within this specific context.

In response to the Reviewer's suggestion, we have revised the Discussion, Limitations, Practical Implications, and Conclusion to adopt a more cautious interpretation of the findings. The revised manuscript now explicitly states that the observed effects may be applicable primarily to athletes with characteristics similar to those of the present sample and that further multicentre randomized controlled trials involving female players of different competitive levels, age groups, and training phases are required before broader generalizations can be made.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Dear Authors

The manuscript has improved considerably following revision, and I appreciate the authors' careful responses to the previous review. The methodological description is now substantially clearer, the discussion is more balanced, and the limitations are appropriately acknowledged. Overall, I believe the manuscript is now close to being suitable for publication.

Only a few relatively minor issues remain that should be addressed before final acceptance:

# Interpretation of partial eta squared

The thresholds currently adopted for interpreting partial η² (small < 0.25, medium = 0.26–0.63, large > 0.63) are not consistent with the criteria most commonly used in the scientific literature. Please replace these thresholds with more widely accepted recommendations or provide an appropriate methodological reference justifying the chosen classification.

Overall, the manuscript has been substantially strengthened during the review process. Subject to the satisfactory correction of the remaining minor issues listed above, I believe it will be suitable for publication in Life.

Comments on the Quality of English Language

The manuscript is generally well written and understandable.

Author Response

Dear Reviewer,

Thank you for this valuable comment. We have revised the interpretation criteria for partial eta squared (ηp²) in the Statistical Analysis section. The previously reported thresholds have been replaced with the more widely accepted criteria of 0.01, 0.06, and 0.14 for small, medium, and large effect sizes, respectively. We have also added an appropriate methodological reference and reviewed the effect-size interpretations throughout the manuscript to ensure consistency with the revised classification.

Best regards.

Reviewer 2 Report

Comments and Suggestions for Authors

Dear authors,

You have responded to my initial comments with professionalism and honesty. For my part, I am happy with all your responses to my initial comments, the clarifications provided, and the amendments made to the revised manuscript.

Best Regards

Author Response

Dear Reviewer,

Thank you very much for your positive and encouraging feedback. We sincerely appreciate the time and effort you devoted to reviewing our manuscript. We are pleased that our responses, clarifications, and revisions have satisfactorily addressed your comments.

Best regards.