Influences of Sex on Muscle Architecture and Performance in Elite Field Hockey Players

Round 1

Reviewer 1 Report

Please refer to the attached document.

Comments for author File: Comments.pdf

Comments included in the main document. 

Author Response

The authors would like to thank the reviewer for his suggestions and effort in the improvement of the overall manuscript quality. According to the reviewer, the manuscript has been extensively updated and checked by a Native English speaker.

Generic comments

Thank you for the opportunity to review this manuscript. The paper aimed to investigate ‘The aim of

this study was to compare muscle architecture and performance between male and female Elite Field

Hockey players investigating the relationships between echo intensity and performance.’

With regards to language, the manuscript may need some moderate to major improvements

throughout.

In general, this paper showed major concerns with regards to the introduction, aims and hypothesis,

methods and design, discussion and conclusions.

My major concerns are summarized here:

1. Rationale of the study and main dependent variables left unexplained
2. Lack of research in the area needs to be specifically addressed
3. Methods: particularly, authors need to report the reliability of the measures and to provide more

information about procedures (and briefly report the characteristics of the technologies used)

4. Improve the statistical approach
5. Discussion needs a lot more work around present findings and compare/contrast with previous

studies of similar characteristics, and to avoid being speculative.

6. Practical applications are lacking
7. Conclusions must be thoroughly improved.

Below you will find a more detailed description of the major/minor concerns.

Specific Comments

Abstract

Lines 13-15: the aim is not clear, possibly authors need to revise wording and implement two different

aims. In addition, the title 'muscle quality' is not accurate mainly because you are analyzing muscle

architecture, therefore authors need to be more precise. Amended, quality has been replaced with Architecture in the title. The first sentence of the abstract has been reworded as follows: The aim of this study was to compare muscle architecture and performance between male and female Elite Field Hockey players and to investigate the relationships between echo intensity and performance.

Line 18: please start off with: Results showed... in line 21, Males were faster... rather than M. Amended

Please consider to remove acronyms for M and F, not really needed. Revise throughout. Amended, M and F have been replaced with male and female.

 

2

Introduction

Overall, introduction need to better explain the rationale for conducting the study. Further adjustments

are needed for the aims and Hpo.

Lacks clarity, overall moderate english corrections are needed. The rationale for conducting the study

is unclear and a major issue. A better organization of paragraphs and ideas is critical to improve the

section. Lastly authors need to provide some context and justification of why and how the hypothesis

were established,

Lines 31-32: the first part of the sentence need proper ref for field positions and sex differences.

Reword sexes to sex and revise throughout.

Line 36: I don’t think 'contexts ‘is the right word here. Also please clarify which sports have

investigated these differences. The sentence has been changed as follows: Differences in strength and power between male and female individuals have been widely investigated in both trained [3,4] and untrained individuals [5].

Line 36 and throughout: please don’t use female and women interchangeably. Be consistent. Amended

Lines 37-39: first, reword to relative strength (i.e. relative to body mass), second how is strength

considered in relation to muscle architecture?? “Or muscle architecture” has been removed.

Lines 41-42: please include r and p values for this sentence. Also please reword for an easier reading. Amended; the following information have been included:  (r=0.5; p=0.034 and r=0.62; p=0.006, between fascicle length and sprint and change of direction, respectively)

Line 45: Start off the sentence differently. ‘Some authors’ is not appropriate. Amended: The sentence has been changed as follows: Hirsch and colleagues indeed, reported….

Lines 46-54: I don’t quite see the reason for this lines, it seems the information is out of the scope

given the aims of this study. Amended.  The following sentences have been removed: “Changes in the muscle water content distribution, augmented intramuscular adipose and fibrous tissue, reduce the darkness of the ultrasound image, leading to an elevation of EI.” “In addition, measuring muscle quality with ultrasound may provide an early detection of risk for injury.”

Lines 55-57: what is the reason for this brief paragraph? please merge to the previous one. Amended

Line 55: higher level of EI? please reword to higher values or similar and include measurement units

for this metric. Amended: The following info have been included: (71.2±12.8 and 60.4±12.6 in women and men, respectively)

Line 59: many studies does not align with only two referenced here. Many has been replaced with some.

Lines 62-64: please reword the second aim to improve readability. Regarding first aim, be more

specific about performance. Hypothesis needs to be justified and provide some reasons on how did

authors arrived to such claims? The paragraph has been changes as follows: Thus, the first aim of the present study was to compare male and female Elite Field Hockey players for muscle architecture, EI, strength and power, sprint and change of direction performance. A second aim of the present study was to investigate the ralationships between muscle architecture and performance, in Elite Field Hockey players. Since sport sex is known to influence muscle adaptations to sport training and muscle quality, the authors hypothesized that significant differences may also exist in EI between male and female Elite Field Hockey players. The authors also hypothesized that this parameter of muscle quality may be significantly correlated with strength and power performance in both male and female players.

Methods Section

3

Line 72: please move this to the subjects’ section. Include type of study design. Revise wording and

grammar (e.g., power at the bench press) and be more specific about the assessments performed. Amended. The period has been changes as follows: “The study consisted of a cross sectional experimental design in which all the….”

Line 86: please include body mass and height before each value in both male and female

characteristics.  Amended

Lines 95-97: these should be included in the limitations section. Amended

Lines 99-103: body fat is not an anthropometric measure but rather a body composition. Please be

more clear regarding how all of these variables were obtained, the instruments used and protocols.

As it stands is not sufficient for study replication. Amended

Line 113: examination table?? Amended, “physical therapy table”.

Lines 139-158: same as previous comments. Reorganize the section, specify type of test, equipment

used, protocols, etc. Be more specific, don’t just refer the reader to other studies. Amended, further information about the pro agility test were included.

Additionally, how far from the 1st timing gates did the participants started the test? foot position and

trunk countermovement checked? Same applies for the 30-m test. Amended, more information about the tests have been included.

Possibly a figure indicating testing order may help the reader and reduce the word count.

Lines 159-173: same comments. Why did authors used power instead of velocity? Since an encoder

was used and velocity is the main outcome measure and not power. how did authors obtain 1RM and

rel values? The bench press 1RM was tested as described in line 172-176: The 1-RM test was performed using an incremental method beginning from a baseline of 20 kg and continued until failure in 10 kg increments. Participants were required to perform one repetition with each load observing a rest time of 2 min between the attempts.

The authors agree with the Reviewer that bar velocity may be an important parameter, however we choose to analyze power as a more comprehensive, and extensively used, parameter.

Statistical analysis

Lines 177-188: what if measures were not normally distributed? did authors used Pearson’s r? why

not reporting the reliability of the measures? These are critical to better understand present results and

discussion.  Data were tested for normal distribution using a Shapiro-Wilk test. The p values were all above 0.05, thus the data were normally distributed.

Results Section

Please report reliability (absolute and relative), do not repeat what is already in the tables but rather

summarize the results. Absolute (SEM) and relative ICC) are reported in the methods at the end of each tests description. The results section does not replicate the tables; in the tables the actual values are presented while in the text results of the comparisons (p, CI…).

The results should be presented in the same order they are presented in tables. Amended

Lines 232-240: please revise wording for the entire paragraph. I suggest to include these results into

a figure so readers can observe the points/dispersion. The paragraph has been reworded as follows: Significant correlations were detected between 30-m sprint (time) and VLEI (r = 0.74; p ≤ 0.001), VLcEI (r = 0.85; p ≤ 0.001) and %fat (r = 0.89; p ≤ 0.001). 30m sprint time was also inversely related with bench press 1RM (r = ‒0.72; p ≤ 0.001). Significant correlations were found between TrapMT and bench press peak power (r = 0.60; p ≤ 0.001); bench press AUC (r = 0.51; p=0.003) and bench press 1-RM (r = 0.57; p ≤ 0.001). A significant correlation was also found between %fat mass and VLEI (r = 0.73; p ≤ 0.001), but not between %fat mass and TrapEI (r = 0.25; p = 0.160). No other significant correlations were observed.

 

4

Discussion

The section need to be reorganized according to how the results are presented. Authors should do:

P2: comparisons for muscle architecture and EI

P3: performance measures

P4: correlations

P5 limitations

Amended, the order of the contents presented in the discussion has been updated accordingly.

Spurious correlations may be found if male and female are pooled together. When correlations are

run with highly heterogeneous sample like in this case, then is highly likely you might find spurious

r values. Therefore, please re-run Pearson’s for male and female separately. Amended, the correlations have been calculated separately in the two groups. The section “Correlations between variables” has been rewritten.

Lines 244-246: avoid unnecessary use of acronyms and revise wording. Additionally, if 'expected'

why was this study conducted? What was expected is the difference in strength and power between men and women. The difference in EI in the lower body only was not expected.

Line 248: To start off the 2nd paragraph with 'Finally' seems awkward. Please reword. Amended, as suggested by the reviewer, the paragraph has been moved forward in the section.

Line 249: not sure about 'highly correlated' since correlation are normally classified as: low, mod,

large and very large. Please consider and modify the statistics section too. Amended, “highly “ has been removed.

If correlations were observed only with sprint, then the use of 'performance' is incorrect since

performance is more complex than just sprinting. Be more precise. As suggested by the reviewer, discussion have been deeply updated.

Lines 256-257: authors need to explain more concisely how was this correction applied. Include this

in the methods section. The correction equation is reported in row 131-137, additional information have been included.

Lines 257-261: these lines are somehow contradicting, why using a correction factor if then authors

state that is not actually needed? overall, this is hard to follow. As suggested by the reviewer, discussion have been deeply updated. The correction did not alter the comparison between m and f for EI and cEI. However, the analysis of the correlations between these parameters and sprint performance, showed that the correlation with 30m sprint was significant in both groups using cEI only.

Up to these lines, authors have not discussed any of the results observed. Please provide a thorough

discussion around findings, and if applicable show the reader how present results align/contrast other

similar studies. As suggested by the reviewer, discussion have been deeply updated.

Lines 265-272: it is not clear to me why were these muscles selected? what do they represent and why

are them so important? Moreover, reword lower body to lower limbs since VL is located in the limbs. Trapezius and Vastus lateralis are superficial and easy to detect muscles. This represents an important component when a clear ultrasound image should be collected in order to calculate EI.

Lines 270-273: how that 'brilliant study' aligns with present findings? Amended. The sentence has been removed.

Line 276: bench press power against which loads? Amended: “Peak power”

Lines 278-281: this is unclear and hard to understand. Please revise. Amended, the period has been updated.

5

Lines 284-285: 'the differences between M Field Hockey players and M strength and power athletes

were more evident on VLMT than on Trap MT?' this is not clear at all. Why strength and power

athletes? The following lines (285-291) are too speculative. authors need to really focus on a serious

discussion around the results of the present study. The sentences have been removed

Lines 292-308: how this data be applied as normative data? authors failed to report major issues

related to the test protocol (distance from first timing, control of trunk countermovement, etc.) which

may largely impact testing results and therefore findings regarding differences between male and

female. More information about the testing procedures were included in the methods. However, trunk movements before starting were not specifically controlled in many investigations (Young, Warren, et al. "The use of sprint tests for assessment of speed qualities of elite Australian rules footballers." International journal of sports physiology and performance 3.2 (2008): 199-206. Hopker, James G., et al. "Familiarisation and reliability of sprint test indices during laboratory and field assessment." Journal of sports science & medicine 8.4 (2009): 528.). In the present study, no trunk movements were consent before the start.

Secondly, this paragraph lacks discussion and a clear message for coaches and practitioners on how

present results may help to improve their practices. Suggestions for coaches are included in the conclusion. The present study is more focused on understanding muscle architecture in relation to performance, than on suggesting the most appropriate training for field hockey players.

What about a thorough discussion and implications in terms of the observed associations?

It is correct to report that lower limbs strength was not assessed, but there are several limitations that

are not reported here (e.g., skinfolds, EI has large limitations, etc.) The authors agree with the reviewer that the study present some limitations. In the limitations section the authors listed the most important.

Conclusions

Must be brief and based on findings. As it stands authors are just repeating the results without

summarizing the most important results. Conclusions have been reduced and reformulated.

Thank you

 

Reviewer 2 Report

Without questioning the work and the interest in carrying out a quality study, I believe that the authors have achieved their approach on the phrase: the self-fulfilling prophecy. It is clear and obvious to everyone that between men and women (athletes or not) there are differences in muscle development, due to gender differences and the physiological mechanisms that support these differences.

I recommend the authors to conceptually delimit the phrase muscular architecture in the Introduction. Take into account the fact that this architecture is based on a different bone architecture (between men and women) at the level of shoulders and hips.

In Discussions, after starting with line 273, references about the hormonal profile (men/women) should be added, which obviously refer to the part of strength and muscular development!

Without questioning the work and the interest in carrying out a quality study, I believe that the authors have achieved their approach on the phrase: the self-fulfilling prophecy. It is clear and obvious to everyone that between men and women (athletes or not) there are differences in muscle development, due to gender differences and the physiological mechanisms that support these differences.

I recommend the authors to conceptually delimit the phrase muscular architecture in the Introduction. Take into account the fact that this architecture is based on a different bone architecture (between men and women) at the level of shoulders and hips.

In Discussions, after starting with line 273, references about the hormonal profile (men/women) should be added, which obviously refer to the part of strength and muscular development!

Author Response

Rew 2

The authors would like to thank the reviewer for his suggestions and effort in the improvement of the overall manuscript quality. The manuscript has been extensively updated and updated in the results and discussion session to fit the reviewers queries.

Without questioning the work and the interest in carrying out a quality study, I believe that the authors have achieved their approach on the phrase: the self-fulfilling prophecy. It is clear and obvious to everyone that between men and women (athletes or not) there are differences in muscle development, due to gender differences and the physiological mechanisms that support these differences.

I recommend the authors to conceptually delimit the phrase muscular architecture in the Introduction. Take into account the fact that this architecture is based on a different bone architecture (between men and women) at the level of shoulders and hips.

In the Discussions, after starting with line 273, references about the hormonal profile (men/women) should be added, which obviously refer to the part of strength and muscular development! Amended, the following statement and reference has been included in the discussion: ”Differences in the hormonal milieu, physical size and also social influences between the sexes, may impact muscle quality, size and performance of the different muscle groups in male and female athletes (Stephard, R.L. Exercise and training in women, Part I: influence of gender on performance and training responses. Can J Appl Physiol 2000, 25, 19-34.) “

 

Reviewer 3 Report

Dear authors,

Thank you for the opportunity to review your manuscript! The topic is interesting, but the study could use a bit more detail. Here are my suggestions:

 

 1. Introduction

Line 41-45: Consider explaining this part better as it's quite confusing in its current form.

 

2. Materials and Methods

Overall, the methods section is well described but needs some clarification.

 

2.1. Study Design

Line 72: Please specify the type of research (transversal, cross-sectional etc.). Provide more information about the study design testing procedure, where, when, how many days, and if it was first done by a man or woman. I recommend adding a figure to explain the assessment timeline.

 

2.3. Body composition and muscle architecture assessments

Line 104: Consider adding a schema or picture of the data collection procedure.

 

2.4. Change of direction speed and Sprint testing

Line 144-146: Was this done on the same day? If so, was it too much for the athletes? Could this affect the results?

Line 154-155: Please confirm if all performances were recorded and the best result was used in the analysis.

 

3. Results

Please improve Tables 1, 2, and 3 by including t-test results, effect sizes, and CC values. The data is in the text but should be displayed in the tables for better visibility.

 

I hope these suggestions help improve your manuscript.

 

Looking forward to seeing the revised version!

Author Response

Rev3

Dear authors,

Thank you for the opportunity to review your manuscript! The topic is interesting, but the study could use a bit more detail. Here are my suggestions:

The authors would like to thank the reviewer for his suggestions and effort in the improvement of the overall manuscript quality.

 

1. Introduction

Line 41-45: Consider explaining this part better as it's quite confusing in its current form.

Amended, additional information about the cited studies have been included.

 

2. Materials and Methods

Overall, the methods section is well described but needs some clarification. The section as been updated according to Reviewer 1.

 

2.1. Study Design

Line 72: Please specify the type of research (transversal, cross-sectional etc.). Provide more information about the study design testing procedure, where, when, how many days, and if it was first done by a man or woman. I recommend adding a figure to explain the assessment timeline.

Amended, additional information about the testing protocol have been included and Figure 1 has been added.

 

2.3. Body composition and muscle architecture assessments

Line 104: Consider adding a schema or picture of the data collection procedure.

Amended, additional information about the testing protocol have been included and Figure 1 has been added. 

2.4. Change of direction speed and Sprint testing

Line 144-146: Was this done on the same day? If so, was it too much for the athletes? Could this affect the results? The authors decided to perform all the assessments in the same day in order to be able to involve as many Elite players as possible. Participant were highly trained individuals and the testing protocol was not demanding for them.

Line 154-155: Please confirm if all performances were recorded and the best result was used in the analysis.

The following statement has been added to the methods: “The best performance registered in each test were then analyzed.”

 

3. Results

Please improve Tables 1, 2, and 3 by including t-test results, effect sizes, and CC values. The data is in the text but should be displayed in the tables for better visibility.

Amended, results of statistical comparisons have been included in the tables.

 

I hope these suggestions help improve your manuscript.

 

Looking forward to seeing the revised version!

Thank you

 

Round 2

Reviewer 1 Report

n/a

n/a

Author Response

The authors would like to thank again the reviewer for his/her suggestions.

The manuscript has been checked by a native english speaker and some periods have been reformulated.

Thank you