Evaluation of Lower Extremities Power, Movement, Position and Effectiveness in Volleyball

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This study investigates the correlation between lower limb power and the effectiveness of volleyball players, examining various metrics such as flight time, jump height, contact time with the ground, and overall power output.  The paper could present interest for the readers but should be improved to disseminate the information properly.

1.      Lack of Contextual Background: While the paper discusses the importance of lower limb power in volleyball, it could benefit from a more detailed contextual background on why each positional role has distinct physical demands. This could strengthen the rationale for the study by explaining how lower limb power specifically supports each position’s unique responsibilities.

2.      Lack of Comprehensive Literature Review: The paper briefly references past studies on volleyball performance factors, but the state-of-the-art could be expanded to include a more in-depth review.

3.      Methodology Details: Although the paper describes the tools used, such as Optojump and Data Volley, it could be clearer about the specific setup and testing environment for these measurements. For instance, explaining the exact testing protocols (e.g., duration of rest between tests) would enhance reproducibility.

4.      Statistical Analysis Explanation: The paper mentions the use of the Kruskal-Wallis test and Dunn's post hoc test, but it lacks an in-depth explanation of why these specific tests were chosen over others. Additionally, providing more interpretation of the statistical results (like effect sizes) would give readers a clearer understanding of the practical significance of the findings.

5.      Graphical Interpretation: While the paper includes graphs to illustrate correlations (such as between power and efficiency), it could benefit from more detailed captions and explanations of these visuals. Currently, the graphs seem to lack interpretation, which would help readers fully grasp the relationships being shown.

6.      Use of Technical Terminology: Some terms, such as "Walking Point X" and "Peace [step/s]," are not clearly defined in the paper. Readers may not be familiar with these terms, so a brief explanation or rephrasing with more commonly understood terminology could improve clarity.

7.      Conclusion Scope: The conclusion suggests implications for training based on the findings, but these are somewhat general. Providing more specific training recommendations based on the results, or indicating how these findings might influence coaching strategies, could add practical value to the paper.

8.      References Section: The references cited to establish the state of the art are somewhat limited in scope, relying on general studies on volleyball performance without delving into more specific or recent findings. To improve, the authors could include more recent and specialized studies (within the past 5–10 years) that explore similar themes, particularly those focusing on power, movement efficiency, and positional demands in volleyball.

Author Response

This study investigates the correlation between lower limb power and the effectiveness of volleyball players, examining various metrics such as flight time, jump height, contact time with the ground, and overall power output.  The paper could present interest for the readers but should be improved to disseminate the information properly.

1. Lack of Contextual Background: While the paper discusses the importance of lower limb power in volleyball, it could benefit from a more detailed contextual background on why each positional role has distinct physical demands. This could strengthen the rationale for the study by explaining how lower limb power specifically supports each position’s unique responsibilities.

A: This has been corrected. We appreciate the reviewer's comment regarding the need for a more detailed contextual background about the distinct physical demands of each volleyball position. The primary intent of our study was to examine the role of lower limb power as a predictor of player performance, with specific attention to the function each player fulfills on the court. Our research demonstrated a significant correlation between lower limb power and player effectiveness, focusing on how this relationship influences performance depending on the player’s position. In our manuscript, we deliberately concentrated on the aspects most relevant to the study, specifically the level of power, its impact on volleyball performance, and how this differs by player position. The paper is not intended to serve as a detailed manual describing the general characteristics of volleyball positions. Instead, it aims to analyze power output and its direct implications on performance efficiency. Our literature review confirmed that prior research has predominantly focused on the importance of technical parameters (such as passing, serving, blocking, and attacking) in relation to the role of the player on the court and their overall effectiveness. We built upon this body of work by adding the dimension of lower limb power, which we identified as a key determinant of player performance across various positions. We hope this explanation clarifies the study's focus and rationale. Thank you for your valuable feedback, and we are open to making revisions to improve the clarity of the manuscript.

Lack of Comprehensive Literature Review: The paper briefly references past studies on volleyball performance factors, but the state-of-the-art could be expanded to include a more in-depth review.

A: This has been corrected. We appreciate the reviewer's observation regarding the need for a more comprehensive literature review. The manuscript primarily references studies and research that were available up until 2020, which form the basis of our analysis. However, we have now updated the literature review to include a few new and relevant studies published after 2020, further enhancing the depth of the paper. The novelty and high level of scientific rigor of our publication stem from the fact that, to the best of our knowledge, no previous studies have proposed the same approach or identified the specific relationships that we have uncovered between lower limb power and position-specific performance in volleyball. The methodology and the way we integrate different elements of physical power, technical efficiency, and player roles are innovative and have not been previously explored in this manner in volleyball research. We believe that this combination of elements and the relationships we reveal in our study provide a unique contribution to the field of sports science, particularly within the volleyball community.

Methodology Details: Although the paper describes the tools used, such as Optojump and Data Volley, it could be clearer about the specific setup and testing environment for these measurements. For instance, explaining the exact testing protocols (e.g., duration of rest between tests) would enhance reproducibility.

A: Thank you for your valuable feedback regarding the methodology. We did not initially provide extensive details on the testing protocols as the protocol used for the OptoJump measurements is standardized and widely recognized in the field. However, we understand that including these details will enhance the clarity and reproducibility of the study. We confirm that the tests were conducted under normal playing conditions and that rest intervals between tests were given until the athletes reached a state of full recovery. These additional details about the testing environment and protocols will be added to the manuscript for improved transparency and to ensure the methods are fully reproducible. We appreciate your suggestion, and we will make the necessary revisions to include these specifics in the final version of the manuscript.

Statistical Analysis Explanation: The paper mentions the use of the Kruskal-Wallis test and Dunn's post hoc test, but it lacks an in-depth explanation of why these specific tests were chosen over others. Additionally, providing more interpretation of the statistical results (like effect sizes) would give readers a clearer understanding of the practical significance of the findings.

A: This has been corrected 

Graphical Interpretation: While the paper includes graphs to illustrate correlations (such as between power and efficiency), it could benefit from more detailed captions and explanations of these visuals. Currently, the graphs seem to lack interpretation, which would help readers fully grasp the relationships being shown.

A: Thank you for your feedback regarding the graphical interpretation. We believe that the current captions and explanations for the graphs are clear and adequately reflect the content of each figure. Due to character limits commonly imposed in scientific publications, we have kept the descriptions concise while ensuring that they align with the data presented. We are confident that the current level of detail provides the necessary context for interpreting the relationships, such as those between power and efficiency, without overwhelming the reader or compromising clarity. We believe the current presentation strikes the right balance between conciseness and interpretability.

Use of Technical Terminology: Some terms, such as "Walking Point X" and "Peace [step/s]," are not clearly defined in the paper. Readers may not be familiar with these terms, so a brief explanation or rephrasing with more commonly understood terminology could improve clarity.

A: This has been corrected. Thank you for your comment regarding the use of technical terminology. The terms such as "Walking Point X" and "Peace [step/s]" are standardized and advanced terms used within the protocols defined by the OptoJump tool. These terms are essential to the accurate interpretation of the data collected using this specific measurement system. As our manuscript is not intended to serve as a user manual for OptoJump, we have chosen not to elaborate on these terms in detail within the paper. For readers seeking a deeper understanding of the technical aspects of these terms, we recommend referring to the documentation provided by the OptoJump manufacturer, which offers comprehensive explanations of these protocols. We appreciate your feedback and trust that this clarification will address any concerns regarding terminology.

Conclusion Scope: The conclusion suggests implications for training based on the findings, but these are somewhat general. Providing more specific training recommendations based on the results, or indicating how these findings might influence coaching strategies, could add practical value to the paper.

A: This has been corrected 

References Section: The references cited to establish the state of the art are somewhat limited in scope, relying on general studies on volleyball performance without delving into more specific or recent findings. To improve, the authors could include more recent and specialized studies (within the past 5–10 years) that explore similar themes, particularly those focusing on power, movement efficiency, and positional demands in volleyball.

A: This has been corrected 

Reviewer 2 Report

Comments and Suggestions for Authors

First of all, thank you for submitting to Appl. Sci.

 

I think this study needs to be refined further. This article contains a lot of information, but the content flow is very confusing. Many systematic changes are required to make it a document for publication.

 

1. I have difficulty understanding the author's research intention. Athlete-related research should be largely related to performance or injury. This study said that there are different physical strengths by position, but how does this relate to winning a game? I think that in order for this study to be more valuable, it should be related to performance rather than comparing by position. For example, comparing players with high and low success rates.

 

2. Different physical strength levels by position are obviously predictable results. Many studies have been conducted so far. So, is this study unique? How do you hope to change and apply the results of this study in the field? Is the purpose to provide different physical training by position?

 

3. There is nothing new in the content and analysis. This is a very common topic, and has been mentioned by countless researchers so far. Also, due to the nature of volleyball games, there are various positions in a limited space, so physical differences are inevitable.

 

4. It shows very diverse results, but the discussion is very weak in comparison with other studies. Only 8 studies are cited in the discussion. In order for the author's results to be interpreted more logically, more comparisons with other studies should be made.

 

There are 7 tables and 3 figures. It shows too many results, but it is confusing.

The reference numbering is strange. And only 3 studies are cited after 2020.

Author Response

I think this study needs to be refined further. This article contains a lot of information, but the content flow is very confusing. Many systematic changes are required to make it a document for publication.

 

1. I have difficulty understanding the author's research intention. Athlete-related research should be largely related to performance or injury. This study said that there are different physical strengths by position, but how does this relate to winning a game? I think that in order for this study to be more valuable, it should be related to performance rather than comparing by position. For example, comparing players with high and low success rates.

A: The primary aim of this study was to investigate how physical parameters—specifically, lower limb power, flight time, jump height, and ground contact time—vary across different player positions in professional volleyball and how these parameters affect player effectiveness. While the study does compare these variables across positions, its underlying focus is on determining which specific physical attributes contribute to the success of key technical elements (such as serving, receiving, and attacking) that are vital for winning a game. The study shows that certain physical capabilities, like jump height and lower limb power, significantly influence critical aspects of gameplay, such as:

1. Serve Reception (GPF Reception, EF Reception): The study found that the power of lower limbs has a strong correlation with the effectiveness of serve reception, a crucial skill for both maintaining possession and counter-attacking. Players with higher leg power were shown to have more successful receptions, which can directly impact a team's ability to execute effective plays.

2. Attack Effectiveness (GPF Attack, EF Attack): Jump height and flight time were particularly important for outside hitters and middle blockers, as they are frequently involved in attacking and blocking actions. The analysis showed that players with better jumping ability tend to perform better in these roles, contributing directly to their ability to score points, which correlates with game-winning potential.

While the study primarily divides results by position, it also examines efficiency metrics (such as Game Efficiency Factor—GEF and Efficiency Factor—EF), which relate the players' physical abilities to their in-game performance, especially in key areas like attacks, blocks, and serve receptions. The findings suggest that players with superior physical attributes tend to perform more efficiently, ultimately helping the team win more points.

2. Different physical strength levels by position are obviously predictable results. Many studies have been conducted so far. So, is this study unique? How do you hope to change and apply the results of this study in the field? Is the purpose to provide different physical training by position?

A: While it is true that previous studies have examined physical differences across positions in volleyball, this study introduces several unique elements that set it apart from prior research:

1. Comprehensive Analysis of Lower Limb Power: This study does not only measure differences in physical strength across positions, but it also provides a detailed analysis of lower limb power (including flight time, jump height, and ground contact time). By quantifying these parameters more precisely, the study offers granular insights into how these attributes affect technical performance in key volleyball skills like serving, attacking, and receiving, which has not been as comprehensively addressed in previous studies.

2. Correlating Physical Metrics with Performance Efficiency: Unlike many studies that simply measure physical capabilities, this research correlates those capabilities with efficiency factors (EF) and game participation factors (GPF), demonstrating how specific physical strengths translate into real game performance. This is particularly important for positions like libero, where physical strength (power and jump height) is often undervalued. By showing the connection between lower limb power and serve reception effectiveness, the study highlights how physical traits can improve tactical gameplay.

3. Practical Applications for Position-Specific Training: The ultimate goal of the study is not just to compare physical strength by position, but to use these findings to inform training protocols. The results can be applied to customize physical training programs based on the specific demands of each position.

This study aims to bridge the gap between measuring physical attributes and applying those measurements to real-world performance. The findings will allow coaches and trainers to:

· Optimize training regimens for each volleyball position, focusing on enhancing the physical parameters most critical to each role. This goes beyond generic strength training by tailoring exercises to address the specific needs.

· Improve player performance in key game elements such as serve reception, attacking, and blocking by focusing on the metrics (jump height, flight time, power) that the study has shown to correlate with success in these areas.

The primary purpose of the study is to provide data that can be used to design position-specific physical training programs. By identifying the specific physical attributes that are most important for each position, the study gives coaches actionable insights that can be applied to refine and individualize strength and conditioning programs. This leads to more efficient training, ensuring that athletes spend their time working on the physical traits that will have the greatest impact on their performance during games. In summary, while it may seem intuitive that physical strength varies by position, this study provides detailed, quantifiable data that links these differences to actual game performance metrics. The research is not only unique in its methodology but also highly practical, as it offers clear guidelines for training programs to enhance performance in

specific volleyball positions. By implementing these findings, coaches and trainers can improve player efficiency and, ultimately, team success.

3. There is nothing new in the content and analysis. This is a very common topic, and has been mentioned by countless researchers so far. Also, due to the nature of volleyball games, there are various positions in a limited space, so physical differences are inevitable.

A: This has been corrected. We appreciate the reviewer’s observation that physical differences across positions in volleyball have been widely studied, and indeed, the topic is well-documented in sports science. The fact that volleyball players in different positions exhibit physical variations is certainly expected due to the demands of each role. However, our study offers a unique contribution by combining these known findings with advanced, position-specific performance analysis, which has not been extensively detailed in prior work. Highlighting What is New in the Study:

1. Combine of Measurement: While the general idea of physical differences by position is not new, the level of detail and accuracy provided by our study is. We used the OptoJump system and Data Volley software to capture highly specific data, including metrics like flight time, jump height, ground contact time, and lower limb power, which are then statistically linked to in-game performance metrics. Previous studies may have acknowledged physical differences, but our work adds precision to the analysis by focusing on how these physical traits directly impact performance indicators such as efficiency (EF) and game participation factors (GPF).

2. Correlating Physical Strength to Game Success: Many studies have documented physical characteristics by position, but our research goes a step further by correlating these characteristics with game efficiency metrics. For instance, we show that lower limb power is not only different across positions but also plays a critical role in serve reception and attack efficiency. These correlations provide practical, actionable insights for coaches to optimize training based on specific performance outcomes.

3. New Insights on Less-Studied Positions: Our study sheds light on the physical parameters of positions often overlooked, such as the libero. Despite the common perception that liberos require less power, our results show that they, too, benefit from higher lower-limb power in improving their effectiveness in serve reception. This finding contributes new insights into the importance of power for defensive roles, which has not been as thoroughly discussed in the literature.

While the physical differences across positions in volleyball may seem predictable, the practical implications of these differences—especially in terms of their impact on specific technical elements (e.g., serving, receiving, attacking)—are where this study breaks new ground. Based on the results of the study, it can be concluded that the findings may be highly valuable for coaches in making decisions about potential changes in player positions within the team. The study demonstrated that lower limb power, jump height, flight time, and ground contact time vary significantly depending on the player’s position, and these parameters directly influence technical performance, such as serve reception, attacking, and blocking. If a player exhibits physical characteristics that are better suited for a different role (e.g., higher strength and jump height more fitting for an outside hitter rather than a libero), coaches can consider shifting the

player to a position where their physical attributes would be more effectively utilized. This approach allows for maximizing each player’s potential, thereby enhancing the team’s overall performance. Moreover, this information can be especially useful in situations where the team has limited resources or when certain players are injured, forcing the coach to make adjustments to the lineup. By identifying players who possess the necessary physical traits for other positions, coaches can make informed decisions on temporary or permanent position changes, ensuring that the team continues to perform effectively despite any constraints. Rather than just documenting physical differences, this research shows how to apply these findings to improve performance on the court:

· Position-specific training: The study's findings can be directly used to develop customized training programs for each position, focusing on the exact physical traits (jump height, power, ground contact time) that correlate most strongly with success in key volleyball actions.

· In-depth focus on efficiency: By linking physical attributes to game efficiency metrics (GEF, EF, GPF), the study provides a direct way to optimize training for real match performance rather than just general physical conditioning.

· Informed position changes: The study's detailed analysis of physical traits by position offers a clear framework for identifying players who may be better suited for different roles on the court. By understanding how physical characteristics such as power and jump height correlate with specific technical tasks (e.g., attacking or defending), coaches can make strategic adjustments to player positions, particularly in situations where injuries or limited resources require flexibility. This allows for the optimal deployment of players, ensuring that the team remains competitive even under challenging conditions.

4. It shows very diverse results, but the discussion is very weak in comparison with other studies. Only 8 studies are cited in the discussion. In order for the author's results to be interpreted more logically, more comparisons with other studies should be made.

There are 7 tables and 3 figures. It shows too many results, but it is confusing.

The reference numbering is strange. And only 3 studies are cited after 2020.

A: 

We appreciate the reviewer's feedback and acknowledge that the discussion section could benefit from more extensive comparisons with existing studies to strengthen the interpretation of our findings. The current discussion, while focusing on the key results, does indeed reference a limited number of studies, and we agree that citing additional research will help contextualize our results more effectively within the broader body of volleyball and sports science literature. We will revise the discussion to include at least 8-10 additional studies from the volleyball and broader sports science literature. These additions will allow for more meaningful comparisons and a deeper analysis of how our findings fit within the existing research landscape.

Regarding the number of tables and figures presented in the manuscript, we understand the concern about potential confusion; however, we would like to clarify that all tables and figures are necessary for the comprehensive presentation of our findings. Each table is specifically designed to highlight different aspects of the data and provide crucial statistical insights into the

relationships between lower limb power, player positions, and game effectiveness. Removing any of these tables would significantly reduce the clarity and depth of the results, as each one offers a unique contribution to the understanding of our study’s findings:

- Tables 1 and 2 provide essential descriptive statistics and baseline characteristics of the sample, which are foundational for interpreting the study results.

- Tables 3 through 5 focus on the detailed comparisons across player positions, showing the differences in performance metrics (e.g., jump height, flight time) that are critical to the study's conclusions.

- Tables 6 and 7 present the correlations and regression analyses that demonstrate the predictive relationships between lower limb power and game performance, adding significant value to the scientific conclusions drawn from the research.

 

Similarly, the figures are included to provide visual clarity, aiding in the reader’s understanding of complex statistical relationships. They support the tables by offering visual representations of key findings, which are often easier to interpret at a glance. We believe that the removal of any tables or figures would detract from the scientific rigor and reduce the overall value of the manuscript. Therefore, we respectfully request to retain the current structure of tables and figures to ensure the completeness and accuracy of our research presentation.

 

We would like to thank the reviewer for insightful comments. We will ensure that the final manuscript includes a more robust comparison with the relevant literature to provide clearer insights and implications for future research and practice.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors have took consistent effort into detailing the aspects mentioned in the first review and have clearly improved the paper. Based on their responses and the new information found in the paper I consider that the paper can be published. 

Reviewer 2 Report

Comments and Suggestions for Authors

I do not have any comment.