Review Reports

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Peer Review Report

Title: EXcellence and PERformance in Track and Field (EXPERT) — A mixed-

longitudinal study on growth, biological maturation, performance, and health in young

athletes: Rationale, design, and methods (Part 1)

1. General Comments

The manuscript presents the rationale, design, and methodological framework of the

EXPERT study, an ambitious mixed-longitudinal project addressing growth, maturation,

performance, health, and environmental determinants in young track and field athletes.

The study fills a clear gap in the current literature, where comprehensive longitudinal data

in this sport are scarce. The rationale is strong, the methodological design is detailed, and

the authors frame the project within the bioecological model, which adds conceptual

rigor.

Overall, the manuscript is well structured, readable, and grounded in relevant literature.

Its main strength lies in the breadth of variables considered across multiple ecological

domains. However, the manuscript would benefit from clearer articulation of specific

research questions, improved coherence between the theoretical framing and the

operationalization of measures, and more precision in describing certain methodological

procedures. Some sections are verbose and may benefit from stylistic tightening to

improve clarity.

2. Major Issues

1. Clarity of Research Questions and Hypotheses

While the rationale is comprehensive, the manuscript does not articulate explicit research

questions or testable hypotheses. A large-scale longitudinal design such as this one should

clearly define:

• which developmental trajectories are expected,

• how specific individual and environmental predictors are hypothesized to operate,

• and the anticipated interactions across domains.

Recommendation: Include a concise subsection outlining primary and secondary

research aims or hypotheses to enhance conceptual clarity and guide future analyses.

2. Integration of the Bioecological Framework

Although Bronfenbrenner’s bioecological model is invoked as the guiding framework,

this theoretical lens is not consistently integrated with the measurement plan. The four

measurement domains correspond to ecological levels, but the manuscript does not

explicitly map them onto microsystem, mesosystem, exosystem, and macrosystem

processes. Without this mapping, the theoretical connection remains somewhat

superficial.Recommendation: Strengthen the theoretical-methodological integration by explicitly

indicating how each measured variable operationalizes components of the model and how

the design will allow examination of person–process–context–time interactions.

3. Methodological Transparency in Sampling and

Recruitment

The manuscript states that 400 athletes will be recruited, but it is unclear:

• how clubs were selected,

• how representativeness is ensured,

• and what inclusion/exclusion criteria apply (e.g., training experience, injury

status).

Given the heterogeneity across clubs and cities, more detail is needed to assess potential

biases.

Recommendation: Add a clear description of inclusion criteria, recruitment strategies,

and any procedures to minimize sampling bias.

4. Measurement Reliability and Standardization

Although the manuscript mentions rigorous training and pilot studies, reliability

procedures for several tests (e.g., jumps, dynamometry, questionnaires) lack detail.

Mixed-longitudinal designs rely heavily on measurement consistency across years,

locations, and assessors.

Recommendation: Specify inter-rater and intra-rater reliability protocols and anticipated

reliability thresholds, especially for subjective measures such as the FMS Hurdle Step or

questionnaire-based constructs.

5. Statistical Analysis Plan

The manuscript provides sample size justification but does not present an analysis plan.

Given the ambition of the project, readers need an outline of:

• the growth modelling approach (e.g., multilevel modelling, latent growth curves),

• how missing data and dropout will be handled,

• how time will be conceptualized across overlapping cohorts.

Without such guidance, the statistical coherence of the project is difficult to evaluate.

Recommendation: Add a subsection with the anticipated analytical strategy for

longitudinal modelling.

3. Minor Issues1. 2. 3. 4. 5. 6. Stylistic clarity: Several sentences are long and overly dense. A stylistic pass

could improve readability without sacrificing detail.

Consistency in terminology: Terms such as “motor performance,” “physical

performance,” and “fitness” are used interchangeably. Consider standardizing

terminology.

Grammar and punctuation: Occasional small issues (e.g., missing articles,

double periods) should be corrected during final editing.

Figure descriptions: Figure 1 and Figure 2 could benefit from more detailed

captions explaining their relevance.

Motivation and grit scales: While adaptations are mentioned, clarity is needed

on whether translated/adapted items underwent any psychometric validation in

this population.

Ethics statement: Already included, but consider indicating whether assent

procedures for minors were applied.

4. Recommendation

Decision: Major Revision

The manuscript is strong and important, but it requires clearer articulation of research

aims, improved theoretical integration, and more methodological transparency before it

is fully publishable.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

OVERALL COMMENT:

The authors present methodology and framework of a novel large-cohort longitudinal individual, performance, health, and environmental characteristics on competitive outcomes in young track and field athletes.

In the introduction of the manuscript the authors provide an overview of the bioecological model used as framework for the investigation, pointing out how this is the first study to employ this methodology in young track and field athletes.

In the methods section, authors describe how each component of the bioecological model is tested. In this section some inconsistencies are present in terms of verb tenses used. Analysis of sprint running, due to the collection of numerous intermediate times, could be expanded whith analysis of the force-velocity profile (Samozino et al., 2008; Duca et al., 2020). Additionally, considerations should be made regarding the potential effects of dropout on statistical power and sample size.

In the discussion, authors describe the benefits of the study and potential limitations.

In parts of the manuscript, the first plural person “we” is chosen – authors should refrain from this choice and rephrase theses sentences.

The manuscript will benefit from a MINOR REVISION

Please refer to the attached word document for specific comments

Comments for author File: Comments.pdf

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Firstly, I would like to thank you for the opportunity to review this article. I would like to emphasise that the comments made here are intended to improve the article, not to belittle it.

Specific comments: The article presents an opportunity to expand upon the existing literature on the subject. However, it is imperative to consider a number of variables:

Title: The title is clear and expresses conformity with the study proposal.

The Abstract is competently written and provides a lucid overview of the study's aim and proposal. However, when using keywords, try to use different words to those in the title. It is vital to ensure that the keywords do not coincide with those present in the title, as this will serve to minimise the probability of a researcher locating the paper.

 

The Introduction is well-written and presents a good definition of the problem and aims. However, it could be improved and some points should be considered:

It is important to maintain a clear focus on the specific gap in athletics studies and justify the need for the study.

It is recommended that the following points are emphasised more explicitly:

- why previous longitudinal studies do not meet current needs;

- how EXPERT overcomes the methodological limitations of these studies.

Line 45, please, correct the points after etc “… attributes, etc..)”

 

Material and Methods

It's relatively well-written, but needs some tweaking.

On item 2.1 Desing, lines 139-141, please consider deleting the sentence “As previously mentioned, the primary goal of the EXPERT study is to investigate the dynamics of the relationships between the characteristics of young athletes and multiple environmental factors that can affect their motor performance and health-related traits” since, as said, it has already been previously mentioned.

Please, try to reduce the size of Figure 1, either by removing information or by changing its formatting.

On item 2.2 Sample, the description is good, but it would be useful to include a brief explanation of the inclusion and exclusion criteria (e.g. the minimum amount of time spent participating in athletics and health-related factors).

Table 1 is clear, but you could consider:

- adding a more explanatory legend;

- providing a brief description of the rationale for age overlap.

 

In item 2.3. (Procedures, lines 185-187), please provide a detailed description of the 'general warm-up'. Specify the intensity of the continuous running and detail which mobility exercises and running technique drills are used.

In item 2.4.2. Performance domain, it is recommended that the reasons for including or excluding certain tests, especially those related to technical skills specific to athletics, are justified.

 

Discussion:

The discussion is well-founded, but:

It rehashes literature that was already cited in the introduction at length – it is suggested being more concise in some parts.

Some statements could be more critical, especially regarding the expected limitations of the mixed-longitudinal design (e.g. cohort effects).

It would be useful to:

- Reinforce the practical importance of the data for national sports policies.

- Provide examples of how coaches can use the findings in future.

 

Regarding limitations, although well written, it could include:

- limitations in causal inference due to the observational nature of the study;

- possible self-selection bias (structured clubs and athletes may be more likely to adhere).

 

Conclusions:

The conclusion it is concise and in line with the aim of the study.

 

References: A considerable proportion of the references are relevant to the subject under discussion.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

MINOR REVISIONS - EXPERT Manuscript v2

OVERALL RECOMMENDATION: ACCEPT WITH MINOR

REVISIONS

The manuscript has improved substantially. Most major concerns have been addressed,

particularly the statistical analysis section. However, several minor issues require

correction.

ESSENTIAL CORRECTIONS

1. ABSTRACT - Needs restructuring

The abstract lacks clear structure. Revise to:

"Background: Longitudinal research examining individual-environment interactions in

youth athletic development is scarce for track and field. Objectives: The EXPERT study

investigates how individual (anthropometry, maturation, motivation) and environmental

(family, coach, club) characteristics influence developmental trajectories in youth track

and field athletes. Methods: A mixed-longitudinal design will follow 400 athletes (200♂,

200♀; aged 10-14 years) from 40 Portuguese clubs across five cohorts assessed

biannually over three years. Guided by Bronfenbrenner's bioecological model,

assessments encompass individual, performance, health, and environmental domains.

Multilevel growth models will examine trajectories and predictor effects. Conclusions:

EXPERT will provide evidence to optimize training and support holistic youth athlete

development."

2. KEYWORDS - Improve specificity

Replace current keywords with: "youth athletes; track and field; mixed-longitudinal

design; biological maturation; motor performance; bioecological model"

These terms improve indexation and align with international standards.

3. INTRODUCTION - Clarify previous study limitations

The description of TOYA, GYS, and INEX limitations is vague. Specify: "Although the

TOYA, GYS, and INEX studies advanced understanding of youth athlete development,

none examined track and field athletes. Moreover, these studies focused primarily on

physical growth and motor performance, with limited consideration of psychological

traits (motivation, perseverance), health indicators (nutritional status, postural control),

and environmental factors (coach behaviors, club resources)."

4. SPECIFIC AIMS - Condense

The four specific aims are too detailed for the introduction. Reduce to: "Complementary

specific aims include: (i) modeling growth dynamics via distance- and velocity-based

curves; (ii) aligning motor performance with peak height velocity to identify sensitive

periods; (iii) examining trajectory associations with individual and environmentalcharacteristics; and (iv) quantifying inter-individual variability and identifying

predictors."

5. SECTION 2.2 - Reorder subsections

Current order is illogical (recruitment before sample size justification). Restructure as:

• 2.2 Sample [general description]

• 2.2.1 Sample size calculation

• 2.2.2 Recruitment and eligibility criteria

6. EXCLUSION CRITERIA - Specify completely

Current criteria are incomplete. Revise to: "Exclusion criteria include: (i) age <10 or >14

years at baseline; (ii) physical, cognitive, or developmental disabilities requiring adapted

training; (iii) acute or chronic conditions contraindicating physical testing (per medical

documentation); and (iv) inability to provide informed consent/assent."

7. WARM-UP DESCRIPTION - Reduce detail

The warm-up description is excessively detailed. Condense to: "The general warm-up

will consist of continuous running (~5 minutes, low intensity), joint mobility exercises

(foot, hip, shoulder circles; knee flexion/extension; lunges; torso twists; leg swings),

running technique drills (arm swings, ankle drills, skipping), and short accelerations (10

m). Total duration: approximately 20 minutes."

8. MATURITY OFFSET - Acknowledge limitations

Add after the maturity offset description: "Although the maturity offset method has

recognized limitations (prediction error ≈±1 year, reduced accuracy in early/late

maturers), it remains the most feasible non-invasive approach for large-scale field studies.

Sensitivity analyses will compare results using chronological age versus maturity offset

to assess estimation error impact."

Include reference: Malina, R.M.; Rogol, A.D.; Cumming, S.P.; Coelho e Silva, M.J.;

Figueiredo, A.J. Biological maturation of youth athletes: Assessment and implications.

Br. J. Sports Med. 2015, 49, 852-859.

9. PSYCHOMETRIC VALIDATION - Add specific data

The validation paragraph mentions validation but provides no evidence. Add: "The

translated items have been psychometrically validated in Portuguese youth. The Intrinsic

Motivation Inventory demonstrated adequate internal consistency (Cronbach's α: .70-.85)

and satisfactory four-factor structure fit. The Short Grit Scale showed acceptable

reliability (perseverance: α=.78; consistency: α=.73) and model fit (CFI=.94,

RMSEA=.06), supporting construct validity in this population."

10. SPLIT TIMES - Clarify purposeExpand the excellent addition about split times: "Split times will be collected to

characterize performance across acceleration phases (0-5m: reaction/initial acceleration;

5-20m: acceleration; 20-40m: maximum velocity transition) rather than to derive

mechanical force-velocity parameters."

11. HURDLE STEP SUBSAMPLE - Justify 55%

Provide clearer rationale: "Dynamic postural control will be assessed with the Hurdle

Step test in a stratified random subsample (55%, n≈220), given time constraints. This

subsample provides adequate power (>.80) to detect medium effects (f=.25) while

reducing assessment burden. Athletes will be randomly selected within sex × cohort strata

at baseline and reassessed at all time points."

12. STATISTICAL ANALYSIS - Minor clarifications

Revise awkward phrasing:

• "handling missing data will be achieved by analyzing" → "Missing data patterns

will be analyzed to determine missingness mechanisms"

• "as well as their association with" → "and their associations with"

13. DISCUSSION - Condense substantially

The discussion is too long and repetitive with the introduction. Reduce by

approximately 50% by:

• Eliminating redundant background on developmental models

• Shortening the review of previous longitudinal studies

• Condensing the limitations paragraph

• Streamlining expected outcomes

Suggested structure: (1) brief context (2 paragraphs), (2) study strengths (1 paragraph),

(3) limitations (1 paragraph), (4) expected contributions (1 paragraph).

14. MINOR GRAMMATICAL CORRECTIONS

• "It is known" → "Adolescence is recognized as"

• "adopts the Bronfenbrenner's" → "adopts Bronfenbrenner's"

• "carry out a warm-up prior to" → "complete a warm-up before"

• "assessed perseverance" → "assesses perseverance" (tense consistency)

• "will be removed" → "was removed" (already validated)

15. FIGURE 2 CAPTION - Improve concision

Revise to: "Figure 2. Assessment sequence in the EXPERT study. Following athlete

identification and questionnaire completion, participants undergo anthropometry and

hurdle step assessment. After standardized warm-up, athletes complete motor

performance tests in the order shown: handgrip strength, 40m sprint (with splits), sit-ups,medicine ball throws, jumps (standing long jump, squat jump, countermovement jump,

reactive strength), and 1000m run."

16. SUPPLEMENTARY FILE - Verify availability

The manuscript references "supplementary file 1" for additional domain details. Ensure

this file is actually provided with submission.

17. REFERENCE FORMATTING - Standardize

Check all references for consistent formatting, particularly capitalization and journal

abbreviations, which vary throughout.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf