Load–Velocity Relationship and 1RM Estimation of the Free-Weight Squat in Untrained Early-Adolescent Females

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This manuscript examines the load–velocity relationship (LVR) and 1RM estimation in untrained early-adolescent females performing the free-weight back squat. In my view, this is a timely and relevant topic. Velocity-based methods are increasingly used in practice, yet data in untrained youth especially girls are still scarce. From that perspective, the study clearly fills an important gap.

Overall, the manuscript is well written, carefully executed, and methodologically sound. The authors present a clear rationale, use appropriate instrumentation, and apply robust analytical approaches. I particularly appreciate the attempt to separate anchor derivation (T1) from prediction (T2), which helps reduce circularity and strengthens the validity of the conclusions.

That said, there are several points where clarity, interpretation, or presentation could be improved. Most of these are relatively minor and, in my opinion, can be addressed without major restructuring of the manuscript.

Major comments

1. 

While the individualized Optimal MVT approach is clearly described mathematically, I think the practical meaning of this anchor could be explained more intuitively. At times, the term “optimal” may give the impression that this value reflects a physiological threshold, whereas in reality it is an error-minimizing parameter derived retrospectively.

It might help to briefly clarify especially in the Discussion that the Optimal MVT is primarily a statistical construct, not necessarily a biomechanical or neuromuscular threshold. This distinction is important for practitioners who may be tempted to treat it as a stable individual characteristic.

2. 

The suggestion that ~0.375 m·s⁻¹ could serve as a defensible fixed MVT for youth parallel squats is interesting and potentially useful. However, in my opinion, this recommendation should be framed more cautiously.

The sample is relatively small, untrained, and drawn from a single sport context. I would therefore encourage the authors to emphasize that this value is a provisional reference rather than a broadly validated benchmark. A short statement acknowledging that this anchor may shift with training status, maturation, or squat depth would strengthen the applied message.

3. 

The manuscript does a good job reporting group-level bias and mean errors. However, I think the practical implications of the remaining individual variability deserve slightly more emphasis.

Even with the Optimal MVT, a non-trivial proportion of participants still exceeded commonly accepted error thresholds. It might be helpful to explicitly state that, in untrained youth, LVR-based 1RM estimates should be used primarily for load guidance rather than precise load prescription. This point is touched upon, but reinforcing it would improve ecological validity.

 

Minor comments

1. Learning effects between T1 and T2

Although the authors briefly mention familiarization effects as a limitation, I think this issue could be acknowledged earlier in the Results or Discussion. The increases in lifted loads and velocities at lighter intensities suggest a likely learning or confidence effect, which is not surprising in this population.

2. Terminology consistency

In a few places, the manuscript alternates between “minimal velocity threshold” and “minimum velocity threshold.” While this is minor, I would recommend using one term consistently throughout for clarity.

3. Figure 1 description

Figure 1 is informative, but the caption could be slightly more explicit. For example, specifying that the bars represent absolute error (kg) rather than percentage error would improve immediate interpretability.

4. Contextualization with male youth data

Although the focus on females is a clear strength, a short sentence comparing these findings conceptually (not numerically) to what is known in male adolescents could help readers situate the results within the broader youth VBT literature.

 

 

Strengths

 

• Novel focus on untrained early-adolescent females, a clearly underrepresented group

• Careful separation of anchor derivation and prediction sessions

• Use of free-weight squats rather than machine-based alternatives

• Excellent individual LVR fits and transparent reporting of variability

• Clear practical relevance for coaches and practitioners working with youth

 

In my opinion, this is a strong and valuable contribution to the literature on velocity-based training in youth. The main conclusions are well supported by the data, and the methodological quality is high. With some minor clarifications and slightly more cautious framing of the applied recommendations, the manuscript would be well suited for publication.

Author Response

This manuscript examines the load–velocity relationship (LVR) and 1RM estimation in untrained early-adolescent females performing the free-weight back squat. In my view, this is a timely and relevant topic. Velocity-based methods are increasingly used in practice, yet data in untrained youth especially girls are still scarce. From that perspective, the study clearly fills an important gap.

Overall, the manuscript is well written, carefully executed, and methodologically sound. The authors present a clear rationale, use appropriate instrumentation, and apply robust analytical approaches. I particularly appreciate the attempt to separate anchor derivation (T1) from prediction (T2), which helps reduce circularity and strengthens the validity of the conclusions.

That said, there are several points where clarity, interpretation, or presentation could be improved. Most of these are relatively minor and, in my opinion, can be addressed without major restructuring of the manuscript.

We sincerely thank Reviewer 1 for the careful reading of our manuscript and for the constructive and insightful comments. We greatly appreciate the reviewer’s positive evaluation of the study’s relevance, methodological rigor, and contribution to the velocity-based training (VBT) literature in youth, particularly in untrained early-adolescent females, an underrepresented population. Below, we address each comment point-by-point and describe how the manuscript has been revised to improve clarity, interpretation, and applied relevance.

 

Comment 1: While the individualized Optimal MVT approach is clearly described mathematically, I think the practical meaning of this anchor could be explained more intuitively. At times, the term “optimal” may give the impression that this value reflects a physiological threshold, whereas in reality it is an error-minimizing parameter derived retrospectively. It might help to briefly clarify especially in the Discussion that the Optimal MVT is primarily a statistical construct, not necessarily a biomechanical or neuromuscular threshold. This distinction is important for practitioners who may be tempted to treat it as a stable individual characteristic.

Response 1: We agree with this important conceptual clarification. In the revised manuscript, we explicitly state that the Optimal MVT is a statistical, error-minimizing construct, not a biomechanical or neuromuscular threshold. We clarify that it is derived retrospectively to minimize prediction error and should not be interpreted as a stable individual characteristic. This clarification has been added to the Discussion, with explicit applied language to avoid misinterpretation by practitioners.

Comment 2: The suggestion that ~0.375 m·s⁻¹ could serve as a defensible fixed MVT for youth parallel squats is interesting and potentially useful. However, in my opinion, this recommendation should be framed more cautiously. The sample is relatively small, untrained, and drawn from a single sport context. I would therefore encourage the authors to emphasize that this value is a provisional reference rather than a broadly validated benchmark. A short statement acknowledging that this anchor may shift with training status, maturation, or squat depth would strengthen the applied message.

Response 2: We fully agree. The manuscript has been revised to frame ~0.375 m·s⁻¹ as a provisional, population- and protocol-specific reference, rather than a broadly validated benchmark. We now explicitly acknowledge that this value may shift with training status, biological maturation, squat depth, or technical proficiency, and should be periodically verified if used in practice. This clarification appears explicitly in the Discussion and is reinforced in the Conclusions, where we emphasize the provisional, population- and protocol-specific nature of this reference value.

Comment 3: The manuscript does a good job reporting group-level bias and mean errors. However, I think the practical implications of the remaining individual variability deserve slightly more emphasis. Even with the Optimal MVT, a non-trivial proportion of participants still exceeded commonly accepted error thresholds. It might be helpful to explicitly state that, in untrained youth, LVR-based 1RM estimates should be used primarily for load guidance rather than precise load prescription. This point is touched upon, but reinforcing it would improve ecological validity.

Response 3: We agree and have strengthened this point. The revised Discussion and Conclusions now explicitly state that, in untrained youth, LVR-based 1RM estimates should be used primarily for relative load guidance and monitoring, rather than precise load prescription. We emphasize that individual-level uncertainty persists despite improvements in group-level bias, and we explicitly caution against using LVR-based 1RM estimates for precise prescription in untrained youth.

Comment 4: Learning effects between T1 and T2. Although the authors briefly mention familiarization effects as a limitation, I think this issue could be acknowledged earlier in the Results or Discussion. The increases in lifted loads and velocities at lighter intensities suggest a likely learning or confidence effect, which is not surprising in this population.

Response 4: This point has been addressed. We now explicitly acknowledge likely learning/familiarization effects in both the Results and Discussion, noting that such effects are expected in untrained youth and may partially explain between-session increases in load and velocity at lighter intensities.

Comment 5: Terminology consistency. In a few places, the manuscript alternates between “minimal velocity threshold” and “minimum velocity threshold.” While this is minor, I would recommend using one term consistently throughout for clarity.

Response 5: Terminology has been standardized throughout the manuscript to “minimum velocity threshold (MVT)” for consistency and clarity.

Comment 6: Figure 1 description. Figure 1 is informative, but the caption could be slightly more explicit. For example, specifying that the bars represent absolute error (kg) rather than percentage error would improve immediate interpretability.

Response 6: The Figure 1 caption has been revised to explicitly state that the bars represent absolute error in kilograms (kg).

Comment 7: Contextualization with male youth data. Although the focus on females is a clear strength, a short sentence comparing these findings conceptually (not numerically) to what is known in male adolescents could help readers situate the results within the broader youth VBT literature.

Response 7: We have added a short conceptual comparison in the Discussion, noting that while youth VBT studies in trained male adolescents report similarly linear load–velocity relationships, sex-, training-status-, and maturation-specific anchors remain necessary and should not be assumed interchangeable.

 

Comment 8: Strengths

• Novel focus on untrained early-adolescent females, a clearly underrepresented group
• Careful separation of anchor derivation and prediction sessions
• Use of free-weight squats rather than machine-based alternatives
• Excellent individual LVR fits and transparent reporting of variability
• Clear practical relevance for coaches and practitioners working with youth

 In my opinion, this is a strong and valuable contribution to the literature on velocity-based training in youth. The main conclusions are well supported by the data, and the methodological quality is high. With some minor clarifications and slightly more cautious framing of the applied recommendations, the manuscript would be well suited for publication.

Response 8: We are grateful for the reviewer’s thoughtful and balanced evaluation. The suggested clarifications have meaningfully improved the conceptual precision, applied framing, and ecological validity of the manuscript. We believe the revised version more clearly communicates both the strengths and the appropriate limitations of LVR-based 1RM estimation in untrained early-adolescent females.

Thank you again for your valuable contribution to improving this work.

Reviewer 2 Report

Comments and Suggestions for Authors

This manuscript presents a well-designed and methodologically rigorous investigation of the load-velocity relationship (LVR) and the estimation of one-repetition maximum (1RM) in untrained early adolescent females. The topic is timely and relevant, as there is a lack of empirical data on velocity-based resistance training specifically for youth, particularly females.

Overall, the study is carefully executed, clearly reported, and well-grounded in current literature. The findings are scientifically sound and carry practical implications for strength training in youth. Only minor revisions are suggested to enhance clarity, contextualization, and transparency.

MAJOR COMMENTS

While the study received approval from an ethics committee and was conducted in controlled conditions, the use of direct one-repetition maximum (1RM) testing in untrained adolescents requires further discussion. Although this type of testing can be safe when adequately supervised, it remains a debated practice within youth populations. The manuscript would be improved by providing a clearer justification for using true 1RM testing instead of submaximal or velocity-derived estimations, particularly since the study’s primary aim is to predict indirect 1RM. A brief discussion that acknowledges this ethical consideration and clarifies why the chosen approach was necessary and justified would enhance the manuscript.

The sample size is supported by a power analysis and is considered sufficient for detecting large effects. However, the relatively small and homogeneous group, consisting of untrained, early-adolescent females from a single sports context, limits the generalizability of the findings. This limitation is especially pertinent given the study’s focus on individual differences and responder classifications. The authors should explicitly acknowledge that the observed patterns of variability and optimal mean velocity threshold (MVT) values may not apply to males, trained youth, or individuals at different developmental stages.

The discussion effectively highlights that, despite the improved accuracy of individualized maximum velocity thresholds (MVTs), significant variability between individuals still exists. This is an important and clearly articulated finding. To enhance the practical relevance of this research, the authors could expand on how practitioners should interpret and implement these findings in real-world situations. For example, they could address how frequently MVTs should be recalibrated and how coaches can manage uncertainty when applying velocity-based prescriptions with youth athletes.

MINOR COMMENTS

Please clarify if the participants' maturation status, such as Tanner stage or estimated peak height velocity, was assessed or taken into account.

 Correct any minor typographical and formatting issues, such as inconsistencies in section numbering (for example, 2.71. RM estimation)

It may also be helpful to condense some of the longer paragraphs in the Introduction and Discussion sections to improve readability.

Verify that the referencing is correct for the journal.

Author Response

This manuscript presents a well-designed and methodologically rigorous investigation of the load-velocity relationship (LVR) and the estimation of one-repetition maximum (1RM) in untrained early adolescent females. The topic is timely and relevant, as there is a lack of empirical data on velocity-based resistance training specifically for youth, particularly females.

Overall, the study is carefully executed, clearly reported, and well-grounded in current literature. The findings are scientifically sound and carry practical implications for strength training in youth. Only minor revisions are suggested to enhance clarity, contextualization, and transparency.

We sincerely thank Reviewer 2 for the careful evaluation of our manuscript and for the positive assessment of its methodological rigor, clarity of reporting, and relevance to youth resistance training research. We particularly appreciate the reviewer’s acknowledgment of the scientific soundness and practical implications of the work. Below, we address each comment in detail and describe how the manuscript has been revised to improve clarity, contextualization, and transparency.

 

Comment 1: While the study received approval from an ethics committee and was conducted in controlled conditions, the use of direct one-repetition maximum (1RM) testing in untrained adolescents requires further discussion. Although this type of testing can be safe when adequately supervised, it remains a debated practice within youth populations. The manuscript would be improved by providing a clearer justification for using true 1RM testing instead of submaximal or velocity-derived estimations, particularly since the study’s primary aim is to predict indirect 1RM. A brief discussion that acknowledges this ethical consideration and clarifies why the chosen approach was necessary and justified would enhance the manuscript.

Response 1: We appreciate this important ethical and methodological point. The Methods and Discussion sections now explicitly justify the use of direct 1RM testing as a criterion reference necessary for validating indirect LVR-based estimates. We clarify that testing followed international youth resistance-training consensus guidelines, was closely supervised, and progressed conservatively to ensure safety. We also acknowledge that, although submaximal approaches are preferred in practice, criterion validation requires a true maximal reference in controlled research settings.

Comment 2: The sample size is supported by a power analysis and is considered sufficient for detecting large effects. However, the relatively small and homogeneous group, consisting of untrained, early-adolescent females from a single sports context, limits the generalizability of the findings. This limitation is especially pertinent given the study’s focus on individual differences and responder classifications. The authors should explicitly acknowledge that the observed patterns of variability and optimal mean velocity threshold (MVT) values may not apply to males, trained youth, or individuals at different developmental stages.

Response 2: We agree and have strengthened the Limitations section accordingly. The revised manuscript explicitly states that the observed variability patterns and Optimal MVT values may not generalize to males, trained youth, or adolescents at different developmental stages, and should be interpreted as population- and protocol-specific.

Comment 3: The discussion effectively highlights that, despite the improved accuracy of individualized maximum velocity thresholds (MVTs), significant variability between individuals still exists. This is an important and clearly articulated finding. To enhance the practical relevance of this research, the authors could expand on how practitioners should interpret and implement these findings in real-world situations. For example, they could address how frequently MVTs should be recalibrated and how coaches can manage uncertainty when applying velocity-based prescriptions with youth athletes.

Response 3: We have expanded the Discussion to provide clearer applied guidance. We now suggest that MVTs in untrained youth should be treated as dynamic rather than fixed, with periodic recalibration following familiarization, technical improvement, or strength gains. We also emphasize that velocity-based outputs should be used as decision-support tools, integrated with technical assessment and coach judgment rather than used in isolation.

Comment 4: Please clarify if the participants' maturation status, such as Tanner stage or estimated peak height velocity, was assessed or taken into account.

Response 4: We now explicitly state in the Participants and Limitations sections that biological maturation markers (e.g., Tanner stage or peak height velocity) were not assessed and acknowledge this as a limitation that may contribute to inter-individual variability.

Comment 5: Correct any minor typographical and formatting issues, such as inconsistencies in section numbering (for example, 2.71. RM estimation)

Response 5: All typographical, formatting, and section-numbering inconsistencies have been corrected throughout the manuscript.

Comment 6: It may also be helpful to condense some of the longer paragraphs in the Introduction and Discussion sections to improve readability.

Response 6: Several longer paragraphs in the Introduction and Discussion have been condensed or split to improve clarity and flow, without removing substantive content.

Comment 7: Verify that the referencing is correct for the journal.

Response 7: All references have been reviewed and formatted to comply with the journal’s guidelines, and citation consistency has been verified.