Flat versus Simulated Mountain Trail Running: A Multidisciplinary Comparison in Well-Trained Runners

Round 1

Reviewer 1 Report

No headings in the abstract, see author guidelines.

L9. Psychological but no data seems to be presented in the abstract.

L13 and L99 and L100. Check throughout. Change “consisted in” to “consisted of”.

L15. Lactate is a metabolic parameter. Please change. Or should metabolic change to cardiopulmonary.

L17. “did not change significantly between”. Maybe better to clarify that they were not different between conditions.

Ls 18-19. Not clear what is meant by peaks height and peaks width. Please clarify that these are sEMG parameters.

L22. “variability of muscle activations was affected”. No EMG data is presented in the abstract. Please ensure that conclusions are based on data present in the abstract.

Ensure throughout the manuscript that the V in VO2max, VO2, VCO2 and VE has a dot on it.

L109. Change “(Borg 0-100 scale)” to “(Borg centiMax® Scale, 0-100)”.

L113. Change “0.5 km·h-1 /min” to “0.5 km·h-1 every min”

L115. Why 1%, see doi: 10.1080/02640419608727717. Provide the reference.

L127. Change “ventilation” to “minute ventilation”.

L153. “(different for speed (8, 153 10, 12 km·h-1 )”. It is not clear what would be different. Please clarify.

L173. Subscript for Smax. Please check.

Table 2 “Significant differences between speeds are not reported.” This may be interpreted that there were always differences but not sure whether that is the case. Please provide information that indicates differences between speeds.

L267. “in none of the muscles” Should this be “in the muscles”. Please check.

In the discussion, arousal and hedonic tone are not discussed. I suggest at least to provide a comment.

Ensure to follow guidelines for the references as journals appear with full names and abbreviations. Please check.

Author Response

Please see the attachement.

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript is well-written, interesting and explores the specificity of the terrain surface that the athlete encounters in the practice of trail running.

In addition to the volume (time and/or distance) and accumulated positive and negative unevenness that these athletes must pay attention to in their training process, the specificity of the terrain also represents an additional requirement that needs to be further explored in terms of research. 

Though, some of the specificity of the type of terrain is lost when the evaluation is carried out in a laboratory context. This may represent a limitation of the present study, given that the unpredictable roll variations similar to mountain trail running (URV) is a simulation, and not an actual terrain condition . This idea could be referred to at the end of the discussion.

However, the authors try to explore the effect of terrain instability on neuromuscular activity and energy expenditure, which may have some similarity to the real context of trail running practice, at least in some situations.

 

Specific comments and suggestions:

 

·       Line 10: in the text appears “in two conditions different for treadmill’s movement”. Suggestion: “in two different conditions for treadmill’s movement”.

·       Line 96: Put the legend on the same page as the table.

·       Line 109: Why 0-100 and not 0-10 on the Borg scale?

·       Line 153: It seems to me that there is one more open parenthesis.

·       Line 198: Maybe GraphPad Prism 8.0?

·       Line 286: is missing a space before (18).

·       Line 353: in the text appears “to rise with the rise in running intensity”. Suggestion: “to rise with increasing running intensity”.

·       Line 360: It does not seem appropriate to introduce bibliographical references in the conclusions. If necessary, introduce the idea in the discussion chapter.

·       Lines 361-364: It does not seem to me a conclusion of the study. I think it would be better at the end of the discussion chapter.

 

As an additional opinion: 

-        I believe that the chapter on the conclusions of the study could be improved. This chapter should only report the conclusions of the study, in a clear and objective way.

 

Congratulations on the study!

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

My main observations regarding this article are methodological and related to the evaluation of neuromuscular function.

Probabilistic model
Since the sample size is small (n<30), it is suggested that the adjustment of the variables to the normal distribution be checked.

If these variables do not fit the normal distribution, non-parametric tests or bootstrap techniques should be used.

 

Sample size and power of the study:
A sample size n=20 is indicated to obtain beta=0.80 but the minimum clinically relevant effect size is not indicated.

As it is understood that the sample cannot be increased, it is suggested to calculate the statistical power a posteriori from the size of the effect of the differences, the level of statistical significance and the sample size.

It is necessary to describe the procedure and the software with which said power has been calculated.

 

Effect size

To assess the magnitude of the possible differences between the evaluation moments and the groups, it is necessary to include a statistic that evaluates the size of the effect.

ANOVA of repeated measures

I think the aim of the study is not related to the concept of repeated measures.  It is not intended to study the increase in activation with speed or the interaction between type of terrain and speed, therefore ANOVA of repeated measures is not recommended.

The main hypothesis of this study was “the URV would induce greater neuromuscular activation with consequently greater metabolic and cardiopulmonary responses compared to FC”.

To verify this hypothesis, it is recommended to use a T test (or its non-parametric counterpart) between the measurements of the HR group and the URV.

A secondary aim was to explore whether URV across all running speeds can reduce the rate of perceived exertion while increasing the arousal and hedonic tone, seeing its more engaging character.

To verify this second hypothesis, it is recommended to use the previous T tests in the three situations evaluated (8, 10 y 12).

EMG assessment

The evaluation of muscle activation is carried out through 8 devices located in 8 muscle groups. However, a single activation result is provided.

It is considered that one of the main strengths of the study could be studying differences in activation in the 6 situations evaluated depending on each muscle group.

For this, it is recommended to include a descriptive table with the results of the 8 muscle groups separately. Indicating results in FC and URV at 8, 10 and 12. As well as performing the corresponding analysis of variance tests in each case. In the same way that was recommended for physiological parameters, including the calculation of effect size and statistical power a posteriori is considered essential.

Discussion

The results on the differences in EMG should be discussed in more depth.

RPE, Arousal and Hedonic tone

It is considered that these variables are not sufficiently related to the previous ones to form part of the same article. Its elimination could favor the understanding and coherence of the findings.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Thanks for addressing my comments.

A few points

L108 " No carbon fibre platplatese used in the experimental test."  is not a sentence and revise platplatese.

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

It is necessary to include the results of the normality tests.

Before studying the interaction of the variable speed and type of surface, it would be necessary to understand the isolated effect of each of these grouping variables separately. For this reason, it is still recommended to include comparison tests using speed (anova of 1 factor of repeated measures) and the type of surface (Student's T test for independent samples) as the grouping variable. The calculations must refer to all the spatiotemporal, metabolic and EMG variables of the study.

It is necessary to describe the process for calculating the sample size. It should be stated for which test these calculations have been made and what effect size has been used. In the method it is indicated that Cohen's d is going to be used but then it does not appear in the results.

It is reported in the data analysis section that the Cohen effect size is going to be calculated and the eta squared coefficient is included in the results (I think they are referring to this). This procedure is inconsistent.
It would be useful for any of the proposed effect sizes to include the qualitative rating scale.

It is necessary to include group comparison tests (T test or its non-parametric equivalent) for each pair of comparisons. Thus, the group-velocity interaction could be better understood.
Carrying out these comparisons of URV-HR groups for each velocity and the HR and RPE variables is insufficient. Comparisons should also be made for spatiotemporal parameters and for EMG.

The discussion on EMG should be done muscle group by muscle group. The overview is not enough to understand the possible effect of speed and surface area on muscle activation.

 

Author Response

Please see the attachment

Author Response File: Author Response.pdf