Bilateral Symmetry of Jumping and Agility in Professional Basketball Players: Differentiating Performance Levels and Playing Positions
, Miran Pehar 2, Toni Modric 1, Vladimir Pavlinovic 1, Miodrag Spasic 1, Ognjen Uljevic 1, Marin Corluka 2, Tine Sattler 3 and Damir Sekulic 1,*Round 1
Reviewer 1 Report
This paper reports on the symmetry of jumping and both planned and reactive agility tasks in professional basketball players, and specifically evaluates there are differences based on “performance levels” (first versus second division) and player position (guards, forwards, centers).
Specific comments:
1) Please insert the word "players" into the article title ("professional basketball players")
2) Elements of this paper, such as the introduction and discussion, emphasize the importance of the performance of these tasks rather than the importance of symmetry. Accordingly, it seems incomplete focus exclusively symmetry, this paper will benefit by reporting and analyzing the actual magnitudes of the performance rather than only the symmetry.
3) You observed a statistically significant interaction for the lay-up jump (Table 2). This interaction is not appropriately interpreted in your manuscript as you interpret the main effects from your model without considering the significant interaction. You have effectively used “the main effect (no-interaction) model” [1]. The significant interaction that you observe means that the amount of symmetry in the lay-up jump differs between guards, forwards and centers depending on whether they are in the first or second division. Accordingly, it is not appropriate to interpret the main effect of performance level (without regard to playing position) in Figure 2, and similarly it is not appropriate to interpret the main effect of playing position (without regard to performance level) in Figure 3. You must perform post hoc testing to drill down to determine the origin of the significant interaction, such as by comparing guards, forwards and centers in the first division, and guards, forwards and centers in the second division. Your misinterpretation of this interaction permeates through your discussion and conclusions requires extensive revision after the correct statistical analysis is performed.
3) The paper refers to "game duties", and at times this appears to be a separate concept than "playing position". If you are referring to the same concept, then please consistently use "plan position" terminology since that appears to be a parameter that is quantified. However, if you are referring to game duties as a different concept than playing position, then you need to describe more fully how this parameter was determined and what it entails.
4) The paper refers to "distinguishing player positions and performance levels” (such as the article title, and lines 28, 33, 92, 251, 255, etc). The paper acknowledges that this is a cross-sectional study and therefore cannot be interpreted as implying causality, and that it should focus on "pure statistical significance" (limitations section). Accordingly, it would be better to word the evaluations of playing positions and performance levels as simple statements about the statistical significance, not “distinguishing”.
5) Performance is described using concepts such as “more successful" (lines 57, 267), “best” (line 144), and “superior” (line 293) at various places in manuscript. It would be better to use terminology that reflect the parameter, such as jumping higher or faster agility tests rather than value-laden concepts.
6) The acronym MRH (line 121) is not defined.
7) The manuscript uses the word "extensive", but only presents one reference (line 146, 160). This does not seem to reflect the ideas that the information is extensive.
8) The manuscript presents that basketball players should perform tasks symmetrically (such as lines 275 – 280). The manuscript describes “dominant side”, but it is unclear whether any tests to determine limb dominance were performed (such as the commonly reported “which foot you kick a soccer ball with” test, or the subjective “preferred versus non-preferred leg”[2]). Finally, the distinction between dominant and non-dominant limbs is blurred in this manuscript since it is operationally defined as the limb with the higher jump or fastest agility test (lines 181 – 183). Given that "leg dominance" is exclusively defined based on performance it seems that it would be better to reframe the comparisons in this manuscript as bilateral symmetry rather than dominant versus nondominant side symmetry.
9) Line 160: please replace "samples" with "participants". Line 189: please replace "here" with "the".
10) The trials need to be described in more detail. For example, you state "three trials with five attempts each" (line 167) and "two attempts, on the right and on the left side, in three trials" (line 169), but it is unclear what is necessary for an attempt to be successful. Was there an element of "rebounding the ball" that was required for successful trial, or was it simply a matter of reacting in the correct direction? Please clarify.
11) The average time was used to determine the dominant side for the CODS task (lines 170 – 172), yet the shortest time on any individual trial was used to describe the "final result" (lines 169-170). This may lead to surprising results. For example, the scenario in which there is a single trial with an outstandingly good performance and on the nondominant limb, less than average performance on the other trials on the nondominant limb, and average performances for all of the trials on the dominant limb would result in symmetry being calculated based on the nondominant task performance. This potential scenario may not be as far-fetched as it seems since test performance may be quite similar between the dominant and nondominant sides.
12) you state that symmetry is equal to a "higher number", and clarify that it should be closer to 1 (lines 181 – 182). Although this is true when you define dominant based on performance, the implication is that it may switch from side to side between tasks, which does not seem to be consistent with the idea of limb dominance. It is more appropriate operationally define it as closer to 1 rather than the higher number.
13) line 198: use superscript for the eta squared symbol.
14) You inconsistently punctuate the Kolmogorov Smirnov test (no hyphen on line 187 and hyphen on line 205).
15) You inconsistently capitalize “d” for the Kolmogorov Smirnov test (“D” on line 205 and “d” in the column title in Table 1). You refer to the “Kolmogorov Smirnov test -KD” in the title for Table 1, but refer to “KS (d)” in the column title in Table 1, which appears to be inconsistent.
16) The critical “d” for the Kolmogorov Smirnov test is not reported in your manuscript. I believe that it is 0.13466 (1.36/sqrt(102)). Table 1 includes three values of d that are equal to 0.13, which you report as not statistically significant. Please report the actual value of the critical d defining the threshold for interpreting statistical significance, and report the values in Table 1 with additional decimal places to allow the reader to evaluate comparisons against the critical d.
17) Your discussion point about the complexity of the task influencing the amount of symmetry (lines 386 – 396) should include additional references related to sport, and ideally basketball, rather than the single reference to soccer.
18) Your wording on lines 397-401 seems inconsistent. First you describe that training on the dominant and nondominant sides improves performance on both sides, and then you describe that performance on the non-dominant side results in improvement on both sides. Your message seems inconsistent.
19) Please replace "less" with "fewer".
References:
[1] Kim HY. Statistical notes for clinical researchers: Two-way analysis of variance (ANOVA)-exploring possible interaction between factors. Restor Dent Endod. 2014;39(2): 143-147.
[2] Šarabon N, Smajla D, Maffiuletti NA, Bishop C. Strength, Jumping and Change of Direction Speed Asymmetries in Soccer, Basketball and Tennis Players. Symmetry. 2020;12(10)
Author Response
REVIEWER 1
This paper reports on the symmetry of jumping and both planned and reactive agility tasks in professional basketball players, and specifically evaluates there are differences based on “performance levels” (first versus second division) and player position (guards, forwards, centers).
Specific comments:
1) Please insert the word "players" into the article title ("professional basketball players")
Response: Thank You. The title is amended accordingly and now states: “Dominant vs. non-dominant side symmetry of jumping and agility in professional basketball players: distinguishing performance levels and playing positions”
2) Elements of this paper, such as the introduction and discussion, emphasize the importance of the performance of these tasks rather than the importance of symmetry. Accordingly, it seems incomplete focus exclusively symmetry, this paper will benefit by reporting and analyzing the actual magnitudes of the performance rather than only the symmetry.
Response: Thank you for your suggestion. In this version of the paper we included additional analyses on differences among playing positions and between performance levels in “crude” performance variables. Text reads: “ANOVA calculations for performance variables showed significant main effects for: (i) playing positions (F-test = 5.04, p = 0.01, large ES; and F-test = 6.26, p < 0.01, large ES, for CODS and RAG, respectively), and (ii) performance levels (F-test = 9.21, p < 0.01, large ES; and F-test = 8.29, p < 0.01, large ES, for CODS and RAG, respectively). For CODS and RAG best performance were evidenced in first division guards (significant post-hoc differences between 1st division guards and 2nd division Centers. No significant ANOVA effects were found for jumping performances.” (please see Results section).
3) You observed a statistically significant interaction for the lay-up jump (Table 2). This interaction is not appropriately interpreted in your manuscript as you interpret the main effects from your model without considering the significant interaction. You have effectively used “the main effect (no-interaction) model” [1]. The significant interaction that you observe means that the amount of symmetry in the lay-up jump differs between guards, forwards and centers depending on whether they are in the first or second division. Accordingly, it is not appropriate to interpret the main effect of performance level (without regard to playing position) in Figure 2, and similarly it is not appropriate to interpret the main effect of playing position (without regard to performance level) in Figure 3. You must perform post hoc testing to drill down to determine the origin of the significant interaction, such as by comparing guards, forwards and centers in the first division, and guards, forwards and centres in the second division. Your misinterpretation of this interaction permeates through your discussion and conclusions requires extensive revision after the correct statistical analysis is performed.
Response: We are particularly grateful for this suggestion. It helped us a lot. In brief, when we observed post-hoc analysis ion more details it actually appeared that differences between performance levels existed specifically for Guards. In other words, symmetry of performance distinguished Guards competing in 1st from those competing in 2nd division (which actually resulted even in significant ANOVA effects for “performance levels” in symmetry of Lay-up jump performance). The results of the post-hoc analysis (together with descriptive statistics) for this particular variable are now presented in Figure 3, and discussed accordingly. In results section text reads: “Since ANOVA interaction was significant for symmetry of lay-up jump (please see Table 2 for details) descriptive statistics and post-hoc differences for this variable are pre-sented in Figure 4. Evidently, significant within position differences were evidenced solely for guards, with better bilateral symmetry of lay-up jump in 1st division guards, than in their 2nd division peers.”. Changes are done in discussion section as well.
3) The paper refers to "game duties", and at times this appears to be a separate concept than "playing position". If you are referring to the same concept, then please consistently use "plan position" terminology since that appears to be a parameter that is quantified. However, if you are referring to game duties as a different concept than playing position, then you need to describe more fully how this parameter was determined and what it entails.
Response: Thank You for your comment. The term “playing position” is used instead of “game duties” in the text where it can lead to misinterpretation.
4) The paper refers to "distinguishing player positions and performance levels” (such as the article title, and lines 28, 33, 92, 251, 255, etc). The paper acknowledges that this is a cross-sectional study and therefore cannot be interpreted as implying causality, and that it should focus on "pure statistical significance" (limitations section). Accordingly, it would be better to word the evaluations of playing positions and performance levels as simple statements about the statistical significance, not “distinguishing”.
Response: Thank You. The term “distinguishing” is changed with “differentiating” in all mentioned places in the manuscript (article title, and lines 28, 33, 92, 251, 255, etc).
5) Performance is described using concepts such as “more successful" (lines 57, 267), “best” (line 144), and “superior” (line 293) at various places in manuscript. It would be better to use terminology that reflect the parameter, such as jumping higher or faster agility tests rather than value-laden concepts.
Response: Thank You for your comment, the text is amended accordingly.
6) The acronym MRH (line 121) is not defined.
Response: The meaning of the acronym is added and read “maximal reach height”.
7) The manuscript uses the word "extensive", but only presents one reference (line 146, 160). This does not seem to reflect the ideas that the information is extensive.
Response: Thank You, the word “extensive” has been removed.
8) The manuscript presents that basketball players should perform tasks symmetrically (such as lines 275 – 280). The manuscript describes “dominant side”, but it is unclear whether any tests to determine limb dominance were performed (such as the commonly reported “which foot you kick a soccer ball with” test, or the subjective “preferred versus non-preferred leg”[2]). Finally, the distinction between dominant and non-dominant limbs is blurred in this manuscript since it is operationally defined as the limb with the higher jump or fastest agility test (lines 181 – 183). Given that "leg dominance" is exclusively defined based on performance it seems that it would be better to reframe the comparisons in this manuscript as bilateral symmetry rather than dominant versus nondominant side symmetry.
Response: Thank You for your observation. We have changed the term “D/ND symmetry” in “bilateral symmetry” across the whole manuscript.
9) Line 160: please replace "samples" with "participants". Line 189: please replace "here" with "the".
Response: Thank You, the text is amended accordingly.
10) The trials need to be described in more detail. For example, you state "three trials with five attempts each" (line 167) and "two attempts, on the right and on the left side, in three trials" (line 169), but it is unclear what is necessary for an attempt to be successful. Was there an element of "rebounding the ball" that was required for successful trial, or was it simply a matter of reacting in the correct direction? Please clarify.
Response: Thank you for your comment. The test is described in detail and the text now reads: “In the RAG tasks, the participant runs from a starting position and lights up one of the cones after crossing the IR signal positioned 1 m from the start, as shown in Figure 1. After recognizing which cone lit up, the participant needs to react in the correct direction and run to that one and rebound the ball placed at the top of the cone with his arms. After that, in order to complete successful attempt, the participant needs to return to the starting position as quickly as possible and the timing stops after crossing the IR signal on the way back. Participants had to perform five attempts in each of three trails. In the CODS tests, participants had the same task, but participants knew in advance which cone will light up and performed two attempts, one on the right and one on the left side, and repeated it in three trials. The shortest time was registered as the final result in all tests.”
11) The average time was used to determine the dominant side for the CODS task (lines 170 – 172), yet the shortest time on any individual trial was used to describe the "final result" (lines 169-170). This may lead to surprising results. For example, the scenario in which there is a single trial with an outstandingly good performance and on the nondominant limb, less than average performance on the other trials on the nondominant limb, and average performances for all of the trials on the dominant limb would result in symmetry being calculated based on the nondominant task performance. This potential scenario may not be as far-fetched as it seems since test performance may be quite similar between the dominant and nondominant sides.
Response: Thank You for your comment. We realize that hypothetically one outstandingly good or bad performance can influence the final results. However, participants had some time to familiarize with the test and by measuring it three times we believe that we minimized potential result discrepancies. Consequently, this could happen extremely rarely because they are experienced professional players and these are not tests in which it is objectively possible to accidentally achieve a good result as, for example, could happen when testing balance. Namely, it is much more probable that a “accidentally bad” result occurs and that by calculating the average we get an unrealistic value.
However, we added this in study’s limitations section:” One of the limitations is the way how finals results in the tests was measured. Namely, the best achieved results for each side was considered as the final and this could lead to surprising results in case of an outstandingly good performance. But given that the participants are professional experienced players and that these are not tests where it is objectively possible to accidentally achieve a good result, we believe that potential result discrepancies could happen extremely rarely.”
12) you state that symmetry is equal to a "higher number", and clarify that it should be closer to 1 (lines 181 – 182). Although this is true when you define dominant based on performance, the implication is that it may switch from side to side between tasks, which does not seem to be consistent with the idea of limb dominance. It is more appropriate operationally define it as closer to 1 rather than the higher number.
Response: Thank You for your observation. The text is amended accordingly and now reads: “In all cases, the value closer to 1 presented better symmetry of performance (note that for jumping we divided non-dominant by the dominant performance, and vice-versa for agility).”
13) line 198: use superscript for the eta squared symbol.
Response: The text is amended accordingly.
14) You inconsistently punctuate the Kolmogorov Smirnov test (no hyphen on line 187 and hyphen on line 205).
Response: Thank You for noticing. The name of the test is now written with hyphen on line on both places.
15) You inconsistently capitalize “d” for the Kolmogorov Smirnov test (“D” on line 205 and “d” in the column title in Table 1). You refer to the “Kolmogorov Smirnov test -KD” in the title for Table 1, but refer to “KS (d)” in the column title in Table 1, which appears to be inconsistent.
Response: Thank You, we capitalize it consistently with “D”.
16) The critical “d” for the Kolmogorov Smirnov test is not reported in your manuscript. I believe that it is 0.13466 (1.36/sqrt(102)). Table 1 includes three values of d that are equal to 0.13, which you report as not statistically significant. Please report the actual value of the critical d defining the threshold for interpreting statistical significance, and report the values in Table 1 with additional decimal places to allow the reader to evaluate comparisons against the critical d.
Response: Thank your comment. The table 1 and legend are amended accordingly. Specifically, KS results are presented in three decimals, and critical value of the “d” is specified in table Legend.
17) Your discussion point about the complexity of the task influencing the amount of symmetry (lines 386 – 396) should include additional references related to sport, and ideally basketball, rather than the single reference to soccer.
Response: Thank You. The additional reference was added and the text now reads: “ Also, in the study on young basketball, soccer and tennis players, authors showed that sport-specific movement patterns and training routines highly affect symmetry performance in different motoric tasks (i.e. strength, jumping, COD) [35].”
- Šarabon, N., Smajla, D., Maffiuletti, N. A., & Bishop, C. (2020). Strength, jumping and change of direction speed asymmetries in soccer, basketball and tennis players. Symmetry, 12(10), 1664.
18) Your wording on lines 397-401 seems inconsistent. First you describe that training on the dominant and nondominant sides improves performance on both sides, and then you describe that performance on the non-dominant side results in improvement on both sides. Your message seems inconsistent.
Response: Thank You for noticing. The text is amended and now reads: “From the perspective of sport performance, it is also important to note that experimental studies showed that training of complex motor skills on the non-dominant sides improves performance on both sides [35]. In a study on professional male soccer players, after an eight-week experiment with increased volume of soccer training with the non-preferred (i.e., non-dominant) leg, results showed an improvement not only on the non-dominant side but also on the dominant side when performing soccer technical tests [36].”
19) Please replace "less" with "fewer".
Response: Thank You, the text is amended accordingly.
Newly added references:
[1] Kim HY. Statistical notes for clinical researchers: Two-way analysis of variance (ANOVA)-exploring possible interaction between factors. Restor Dent Endod. 2014;39(2): 143-147.
[2] Šarabon N, Smajla D, Maffiuletti NA, Bishop C. Strength, Jumping and Change of Direction Speed Asymmetries in Soccer, Basketball and Tennis Players. Symmetry. 2020;12(10)
Thank you for your suggestions and comments.
Staying at your disposal
Reviewer 2 Report
Overall, this is an interesting study and will be read and of interest to applied practitioners. However, at times it seems the authors overreach with interpreting the data, as they found differences in symmetry between training levels, which is likely du to the athletes training. While the reference differences in symmetry being important to outcomes in basketball, their methods don't appear to address that questions, especially as in related to spot-specific performance but also related to physical performance. Overall, I think this is publishable work that could be useful, but the authors need to re-work some of the interpretation of the data. Specific point-by-point comments can be found below.
Page 2, Line 45: Change “is” to “are”
Page 2, Line 52: Check grammar…maybe “A study…”
Page 2, Line 80-86: While superficially this could make sense, however what if a player had faster absolute values of dominant and nondominant COD and RAG speeds than all other players, but still developed a large asymmetry, would this mean he has poorer overall performance? Yes, making his “slower side” faster would improve his performance, but it is still about absolute performance of a side rather than the asymmetry dictating on-court success/outcomes. Additionally, it would make sense from a player profiling to understand where the deficient lies to direct training, however I believe saying that may be different than saying the asymmetry alone hinders performance.
Page 2, Line 83, 85: Make sure “non-dominant” is written the same every time, currently written as “non-dominant” and sometimes as “nondominant.”
Page 3, Line 102: All of the “N” should be lowercase (“n”) because this is a sample not the population.
Page 3, Line 120: Were multiple raters used for Skinfold assessments? If the same or multiple raters, were there intra- and intersession reliability provided due to the variability of the Skinfold assessment and potential for large error rates.
Page 4, Line 173: At some point in the manuscript, please state how limb dominance was determined.
Page 4, Line 189: Revise grammar, “While here observed tests…” not clear what is meant.
Page 5, Line 13 (Table): What does “s” stand for?
It appears this is the first time how dominance was determined, with “better performance being the dominant side. This needs to be supported by previous work or rationalized in more detail. In other asymmetry work, especially of the upper extremity, the dominant hand often has lower absolute performance on a gross task, such as strength, due to individuals using the dominant limb to dexterity movements. Example-Someone carrying groceries into their home, holding them all in the non-dominant hand, so they can use their dexterity of the dominant hands to insert key and unlock/open door. More information needs to be provided to support your methods.
The strategies used to determine asymmetry can effect the observed outcomes. Review Dr. Chris Bishop’s work on asymmetry calculations and their effect on observed asym. None of Bishops work is cited here, and I think numerous study of his are relevant and important to reference.
Page 6, Line 238; Page 7, Line 246: You may consider adding the effect size for the significant observations to these graph to help it stand alone.
Page 7, Line 253: “Second, performance levels significantly differed…I believe this should be D/ND symmetry differed between performance levels. The ordering of these terms could described a different relationship or association and can be confusing.
Page 7, Line 266: A variety of factors are at play affecting the performance of COD performance, these previous works did not measure asym, so its important to make clear you are just comparing the performance between positions, any association with asym from other work is purely speculative.
Page 8, Line 275: Another reason for. Alack of asym could be that performance coaches are (or should be) performing assessments to identify asym and training for that, while also performing a variety of unilateral work that may decrease observed asym. I think this point should be address-how training could be decrease asym, especially better players potentially receiving better training as they progress in their career.
Page 9, Line 340: This statement may be an overstatement of the findings in this study. This could be speculated as important, but this does not “highlight the fact”. This should be toned down and recognized as speculative with the current study design and evidence.
In reference to above comment, the paragraph starting on Page 9, Line 340 is exactly why you cannot jump to the conclusion referenced above. These athletes have more consistent training that could decrease asym once at the level (becoming a member of the higher division team), rather than having a lower asym which allowed them to reach the highest division team. This last paragraph decreases the value of the findings of the manuscript, as it seems players are receiving differences in training, specifically training frequency, which could largely affect the outcomes. This needs to now be addressed as a limitation.
Page 11, Line 454: The study did not confirm sym was importance between playing levels, it only demonstrated potential differences between levels, which is likely due to the training performed by these athletes compared to the lower-level counterparts.
Author Response
REVIEWER 2
Overall, this is an interesting study and will be read and of interest to applied practitioners. However, at times it seems the authors overreach with interpreting the data, as they found differences in symmetry between training levels, which is likely du to the athletes training. While the reference differences in symmetry being important to outcomes in basketball, their methods don't appear to address that questions, especially as in related to spot-specific performance but also related to physical performance. Overall, I think this is publishable work that could be useful, but the authors need to re-work some of the interpretation of the data. Specific point-by-point comments can be found below.
Response: Thank You very much for your suggestions. We amended the manuscript according your comments, especially regarding methods and the interpretation of the data. Please see comments below.
Page 2, Line 45: Change “is” to “are”
Response: Thank You, the text is amended accordingly.
Page 2, Line 52: Check grammar…maybe “A study…”
Response: Thank You for noticing. The text is amended.
Page 2, Line 80-86: While superficially this could make sense, however what if a player had faster absolute values of dominant and nondominant COD and RAG speeds than all other players, but still developed a large asymmetry, would this mean he has poorer overall performance? Yes, making his “slower side” faster would improve his performance, but it is still about absolute performance of a side rather than the asymmetry dictating on-court success/outcomes. Additionally, it would make sense from a player profiling to understand where the deficient lies to direct training, however I believe saying that may be different than saying the asymmetry alone hinders performance.
Response: Couldn’t agree more! Thank You for your observation, the text is rephrased and now reads: “However, it is reasonable to expect that successful jumping and agility performance on both the dominant and non-dominant sides would be beneficial for specific playing positions in basketball. Although absolute performance values on both dominant and non-dominant sides would most significantly effect on-court performance, better symmetry (i.e., minimization of the differences between the dominant and non-dominant sides) would theoretically enhance players’ ability to perform successfully on both sides, which could contribute to overall performance in the game. „
Page 2, Line 83, 85: Make sure “non-dominant” is written the same every time, currently written as “non-dominant” and sometimes as “nondominant.”
Response: Thank You for noticing, the line is added every time the word is mentioned in the text.
Page 3, Line 102: All of the “N” should be lowercase (“n”) because this is a sample not the population.
Response: Thank You, all letters are lowercased.
Page 3, Line 120: Were multiple raters used for Skinfold assessments? If the same or multiple raters, were there intra- and intersession reliability provided due to the variability of the Skinfold assessment and potential for large error rates.
Response: Thank You, additional sentence is added and reads: “Same investigator measured skinfolds for all tested participants in order to minimize unsystematic measurement errors.”
Page 4, Line 173: At some point in the manuscript, please state how limb dominance was determined.
Response: Thank You for your comment. Given the character of the tests, especially agility, we tried to avoid “limb” throughout the text and we talked about dominant and non-dominant sides. But as the 1st reviewer suggested, we changed the term "D / ND symmetry" to "bilateral symmetry" throughout the manuscript as it is more suitable.
Page 4, Line 189: Revise grammar, “While here observed tests…” not clear what is meant.
Response: Thank You for noticing. The text is amended and now reads: “While the observed tests...”
Page 5, Line 13 (Table): What does “s” stand for?
Response: Thank You for noticing. It is misspelled, “s” stands for seconds, and “cm” is added for variables where final results was expressed as distance.
It appears this is the first time how dominance was determined, with “better performance being the dominant side. This needs to be supported by previous work or rationalized in more detail. In other asymmetry work, especially of the upper extremity, the dominant hand often has lower absolute performance on a gross task, such as strength, due to individuals using the dominant limb to dexterity movements. Example-Someone carrying groceries into their home, holding them all in the non-dominant hand, so they can use their dexterity of the dominant hands to insert key and unlock/open door. More information needs to be provided to support your methods.
Response: Thank You for your observation. As we explained in one of previous comments, we avoided to use dominant and non-dominant limb and used the term “side” instead of it as in complex movements, such as in agility tests, we can not talk about dominant and non-dominant sides based just on the limbs. Since your comment is in line with the opinion of the first reviewer, we believe that by replacing "d/nd symmetry" with "bilateral symmetry" we corrected this issues.
The strategies used to determine asymmetry can effect the observed outcomes. Review Dr. Chris Bishop’s work on asymmetry calculations and their effect on observed asym. None of Bishops work is cited here, and I think numerous study of his are relevant and important to reference.
Response: Thank You for your comment. We reviewed Dr. Chris Bishop asymmetry studies and amended the text accordingly: “ There are multiple methods used to calculate symmetry levels and the selection depends on a number of factors [23]. Although percentage difference method is recently suggested as most appropriate to estimate asymmetry levels, we used Limb symmetry index 1 which is calculated by dividing the performance from the non-dominant leg by the corresponding performance from the dominant leg [23,24]. Actually, Limb symmetry index 1 is more of a measure of limb symmetry then the asymmetry and results of percentage difference method, although seems different, shows values at the opposite end of the asymmetry spectrum[25]. ” (please see last paragraph of 3.3. sub-section for more details)
Page 6, Line 238; Page 7, Line 246: You may consider adding the effect size for the significant observations to these graph to help it stand alone.
Response: We never did it so far, so thank you! ESs are included in all Figure
Page 7, Line 253: “Second, performance levels significantly differed…I believe this should be D/ND symmetry differed between performance levels. The ordering of these terms could described a different relationship or association and can be confusing.
Response: Thank You, the text is rewritten and now reads: “Second, D/ND symmetry differed between performance level, with better symmetry found for players who compete at a more advanced level.”
Page 7, Line 266: A variety of factors are at play affecting the performance of COD performance, these previous works did not measure asym, so its important to make clear you are just comparing the performance between positions, any association with asym from other work is purely speculative.
Response: Thank You for your comment, we agree that it can speculative. However, we rephrased the text and now it reads:” Although cited studies investigated specifically position differences in COD performance, which are under influence of many factors, the results presented here of non-significant differences among positions in D/ND symmetry of agility performances are not unexpected.”
Page 8, Line 275: Another reason for. Alack of asym could be that performance coaches are (or should be) performing assessments to identify asym and training for that, while also performing a variety of unilateral work that may decrease observed asym. I think this point should be address-how training could be decrease asym, especially better players potentially receiving better training as they progress in their career.
Response: Thank You for your comment, we completely agree and we rewritten this part of discussion. The text now reads: “The main reasons for the lack of difference among positions in bilateral symmetry of CODS and RAG should be found in (i) characteristics of movement types during the game and (ii) the specifics of the CODS and RAG tests applied here and (iii) possibility that strength and conditioning coaches perform assessments to identify asymmetry and organize training with goal to decrease observed asymmetries.”
“Also (iii) strength and conditioning coaches on professional level very often perform battery of tests to evaluate disbalance in flexibility, mobility or strength. With information about eventual asymmetry or disbalance, coaches can create additional training programs in order to correct these deficiencies and additionally develop player’s abilities.” (please see last paragraph in 4.1. sub-section)
Page 9, Line 340: This statement may be an overstatement of the findings in this study. This could be speculated as important, but this does not “highlight the fact”. This should be toned down and recognized as speculative with the current study design and evidence.
Response: Thank You for your comment. The text is rewritten and now reads: “Our results suggest that players who possess better D/ND one-leg jumping symmetry could potentially meet the requirements of playing at a higher competitive level.”
In reference to above comment, the paragraph starting on Page 9, Line 340 is exactly why you cannot jump to the conclusion referenced above. These athletes have more consistent training that could decrease asym once at the level (becoming a member of the higher division team), rather than having a lower asym which allowed them to reach the highest division team. This last paragraph decreases the value of the findings of the manuscript, as it seems players are receiving differences in training, specifically training frequency, which could largely affect the outcomes. This needs to now be addressed as a limitation.
Response: Thank You for your comment, we absolutely agree. Indeed this is explained in the last paragraph of 4.3. sub-section: “Although the previous discussion overviews the logics of the performance-level differences in D/ND one-leg jumping symmetry, the context of such results also deserves attention. Being actively involved in training process of the studied players, authors of the study are of the opinion that the main reason for better symmetry of the 1st division players (guards primary) should be found in their training process. Namely, the 1st division players generally participate in more structured training process than their 2nd division peers. In addition, 1st division players have higher frequency of training (more training hours per week), and are systematically trained in position-specific technical-tactical performances. For jumping, the 1st division players (mainly guards) are systematically trained in “both sides”, and attention is paid on performance on dominant and non-dominant side. Meanwhile, mostly because of the smaller training frequency, coaches in 2nd division are mostly focused on tactics, which doesn’t allow them to pay attention on eventual technical deficits of their players. Training sessions for 2nd division teams are therefore less structured and mostly based on free play with different numerical ratios. It altogether results in the fact that 1st division players are more able to develop both technical-tactical skills and specific conditioning capacities than their 2nd division peers simply because of the quality of the training process.”
However, we added text in the study’s limitations subsection to highlight this issues (please see Limitations and strength of the study sub-section).
Page 11, Line 454: The study did not confirm sym was importance between playing levels, it only demonstrated potential differences between levels, which is likely due to the training performed by these athletes compared to the lower-level counterparts.
Response: Thank You, this part of conclusion is rewritten and now reads: “The study demonstrated N/DN symmetry differences between playing levels. Although cause-and-effect relationships are unclear as potential reason for differences can lie in different traing regimes, it can be assumed that symmetry may play an important role in other competitive sports as well.”
Thank you for your suggestions and comments.
Staying at your disposal
Reviewer 3 Report
ABSTRACT
Lines 15-16: such a claim must be deeply supported in the introduction. In fact, on many levels, functional asymmetry is normal in athletes. Take a look at the ebook “Asymmetry as a Foundational and Functional Requirement in Human Movement”
Lines 19-20: add eligibility criteria in brief
Lines 29-31: add the effect size after the p-values
INTRODUCTION
Lines 40-41: add references to support the statement.
Lines 44-45: is not perfectly connected with the previous phrase, can be better linked. Also, add the justifications for such facts.
Line 68: add references to support the statement.
Lines 86-70: maybe the link with the previous phrase is not the best. The rationale can be improved.
Lines 70-78: it would be interesting to report some bias of these studies, namely considering that many times the time of training intervention exposure and considering for type of drills are not considered in the analysis.
Line 90: add a statement of contribution that may help the readers to understand the pertinence of this study for coaches and the research community.
METHODS
Line 98: before participants, add a sub-section of “experimental approach to the problem”. In this section, start by adding the study design type. After that, describe the experimental approach and describe the setting, locations, and relevant dates, including periods of recruitment, exposure, follow-up, and data collection.
Line 99: add the a priori sample size calculation.
Line 104: Give the eligibility criteria and the sources and methods of selection of participants.
Line 113: organize this section and starts providing key elements regarding the reproducibility of experimental conditions (local, temperature, sequence (order of tests), warm-up protocol, days of recovery before, time of the day)
Lines 125-126: add the reliability level of the observer to collect these measures.
Lines 130-131: two or three trials? Which criteria were used? Why this variance?
Line 135: add the validity and reliability of the instrument to quantify the outcome.
Lines 136-138: considering the running is self-paced how the reliability of conditions is ensured among players? Add the validity and reliability levels of this test.
Line 140: how the final result was measured and obtained?
Line 147: add the exact levels of “validity and reliability”
Line 160: add the exact level that justifies the validity and reliability of the test.
RESULTS
Figures 2 and 3: in the y-axis add the unit of measurement. Above the “*” add the exact p-value and effect size
DISCUSSION
Add future research proposes within section 4.5
Add a sub-section of practical implications.
Author Response
REVIEWER 3
ABSTRACT
Lines 15-16: such a claim must be deeply supported in the introduction. In fact, on many levels, functional asymmetry is normal in athletes. Take a look at the ebook “Asymmetry as a Foundational and Functional Requirement in Human Movement”
Response: Thank You for your comment. The sentence is rewritten and now reads: “: Although functional asymmetry is very common and normal in professional athletes, better inter-limb symmetry between dominant and non-dominant sides (D/ND symmetry) could contribute to successful performance in basketball.”
Lines 19-20: add eligibility criteria in brief
Response: Thank You, eligibility criteria is added and the text now reads: “The participants were 102 professional male basketball players, at the moment of testing allmembers of the teams competing in the two highest national divisions.”
Lines 29-31: add the effect size after the p-values
Response: Added as suggested. Text reads: “Factorial analysis of variance (Performance levels × Positions) indicated that bilateral symmetry of one-leg jumping differentiated players according to their playing position, with better bilateral symmetry among guards (F-test = 6.11 (medium effect size) and 5.81 (small effect size), p < 0.05 for Lay-up and Running-jump symmetry, respectively). Performance levels significantly differed in bilateral symmetry of Lay-up jump, with better symmetry for first division players (F-test = 10.11 (medium effect size), p < 0.001).”
INTRODUCTION
Lines 40-41: add references to support the statement.
Response: Thank You, the reference is added.
- Abdelkrim, N. B., Chaouachi, A., Chamari, K., Chtara, M., & Castagna, C. (2010). Positional role and competitive-level differences in elite-level men's basketball players. The Journal of Strength & Conditioning Research, 24(5), 1346-1355.
Lines 44-45: is not perfectly connected with the previous phrase, can be better linked. Also, add the justifications for such facts.
Response: Thank You for your comment. The text is rewritten and now reads: “In all phases of the game players perform the various technical and tactical tasks that are directly influenced by various fitness capacities such as speed, agility, strength and power [3,4]. Previous studies showed that physical abilities have big importance on the game performance [5].”
Line 68: add references to support the statement.
Response: Thank You, the references are added.
- Pehar, M., Sekulic, D., Sisic, N., Spasic, M., Uljevic, O., Krolo, A., Milanović, Z. & Sattler, T. (2017). Evaluation of different jumping tests in defining position-specific and performance-level differences in high level basketball players. Biology of sport, 34(3), 263.
- Pehar, M., Sisic, N., Sekulic, D., Coh, M., Uljevic, O., Spasic, M., Krolo, A. & Idrizovic, K. (2017). Analyzing the relationship between anthropometric and motor indices with basketball specific pre-planned and non-planned agility performances. The Journal of sports medicine and physical fitness, 58(7-8), 1037-1044.
Lines 66-70: maybe the link with the previous phrase is not the best. The rationale can be improved.
Response: Thank You for your observation. The text is rewritten and now reads: “Generally, there is a global consensus that agility performances (RAG and CODS), and vertical jumping performances contribute to success in basketball [13,17]. However, recent studies contextualized the aspect of bilateral symmetry in jumping and agility performance with regard to manifestation of these motor abilities on players’ dominant and non-dominant sides [13,16]”
Lines 70-78: it would be interesting to report some bias of these studies, namely considering that many times the time of training intervention exposure and considering for type of drills are not considered in the analysis.
Response: Thank you, the mentioned bias is specified and text reads: “However, it must be noted that all cited studies were cross-sectional, and therefore we cannot undoubtedly speak about eventual causality between observed independent- and dependent-variables since in most cases time of training intervention exposure and type of drill applied are not considered in the interpretation of the results.” (please see end of the 4th paragraph of the Introduction).
Line 90: add a statement of contribution that may help the readers to understand the pertinence of this study for coaches and the research community.
Response: Thank You. The sentence is added and reads: “These evaluations could provide important information to basketball coaches and practitioners in process of selection and training programming.”
METHODS
Line 98: before participants, add a sub-section of “experimental approach to the problem”. In this section, start by adding the study design type. After that, describe the experimental approach and describe the setting, locations, and relevant dates, including periods of recruitment, exposure, follow-up, and data collection.
Response: Thank you for your suggestion. The subsection 3.1. Experimental approach to the problem is added and txt reads: The experimental approach consisted of four phases. In the first phase of the study, we made an a priori estimation of the sample size. To obtain the sample size estimate, we used data obtained in pilot testing of 20 athletes. In short, we have tested 10 first division and 10 second division players and compared their jumping and agility achievement on tests used in this study. An analysis using G*Power software (version 3.1.9.2; Heinrich Heine University Düsseldorf, Düsseldorf, Germany) for independent t-tests (using a 2-tailed p-value of 0.05, power of 0.90 and effect size of 0.5) recommended ≤ 71 partici-pants altogether as an appropriate sample size (ranging from 60 to 71, depending on per-formance test). The second phase included testing and analyzing the intra-testing reliabil-ity of the performance tests, and calculation of the symmetry indexes (please see later for details). This phase lasted two months (from early September to late October 2019). In the third phase, we examined the ecological validity of the performance tests and symmetry indexes while comparing the results (i) among playing positions and (ii) between perfor-mance-levels.”
Line 99: add the a priori sample size calculation.
Response: The a priori sample calculation is added and text reads: An analysis using G*Power software (version 3.1.9.2; Heinrich Heine University Düssel-dorf, Düsseldorf, Germany) for independent t-tests (using a 2-tailed p-value of 0.05, power of 0.90 and effect size of 0.5) recommended ≤ 71 participants altogether as an appropriate sample size (ranging from 60 to 71, depending on performance test).”
Line 104: Give the eligibility criteria and the sources and methods of selection of participants.
Response: Text is added and reads: “Only players who had no injuries and/or illnesses for 20 days before the testing were observed in this study. The health status was based on team physician’s opinion/report. No players were taking substances that might be expected to affect their performance on study tests.” (please see end of the 3.2. subsection)
Line 113: organize this section and starts providing key elements regarding the reproducibility of experimental conditions (local, temperature, sequence (order of tests), warm-up protocol, days of recovery before, time of the day)
Response: Thank You. The text is amended accordingly and now reads: “Jumping and agility testing was conducted in an indoor gymnasium with a wooden floor. Conditions were similar for all participants and included one day rest before measurements, standard basketball floor, temperature 20-25˚ C, self-preferred type of footwear and time of the day (between 9 and 11 AM). Before measurement, all players completed a 15-minute warm up protocol that consisted of jogging (5 minutes), mobility exercise (5 minutes), dynamic stretching (3 minutes), and activation (2 minutes), which included skipping and light jumping.” (please see 3.3. methods sub-section for more details).
Lines 125-126: add the reliability level of the observer to collect these measures.
Response: Details are added, and text reads: “Same investigator measured skinfolds for all tested participants in order to minimize unsystematic measurement errors. All measurement procedures were obtained in ac-cordance with the International Biological Program, with observer’s reliability levels ICC ranging from 0.78 (for suprailiac-skinfold), up to 0.99 (for body height) [22].”
Lines 130-131: two or three trials? Which criteria were used? Why this variance?
Response: Actually, players were given three times for familiarization with the test. This was based on evaluators previous experience with this kind of assessments. However, some of them perform only two repetitions as they estimated that was adequate. But for better understanding the text is rewritten and now reads: “Before both jumping and agility tests, players were given three trials in order to familiarize themselves with all tasks.”
Line 135: add the validity and reliability of the instrument to quantify the outcome.
and
Lines 136-138: considering the running is self-paced how the reliability of conditions is ensured among players? Add the validity and reliability levels of this test.
Response: Thank you for your suggestions. Details on reliability of the measurement are added in the Results section and text reads: “Intra-testing reliability of agility- and jumping-tests was appropriate to high (ICC: 0.80-0.91; CV: 9% to 5%).” (please see end of the 1st paragraph of the Introduction)
Line 140: how the final result was measured and obtained?
Response: Thank You for your comment. It is explained and the text reads: “The final result of the test was calculated as the difference in centimeters between reached height after the jump and the participants’ standing vertical reach.”
Line 147: add the exact levels of “validity and reliability”
Response: Details are added, and text now reads: “The reliability and validity of the jumping tests used in this study was previously reported to be appropriate to high (ICC: 0.80-0.85, and 0.86-0.88 for inter-testing and intra-testing reliability, respectively)” (please see end of the 6th paragraph in Variables subsection)
Line 160: add the exact level that justifies the validity and reliability of the test.
Response: Details are added, and text reads: “The reliability and validity of the tests have previously been evaluated and confirmed on similar participants with inter-testing reliability obtained by ICC ranging from 0.81-0.90 [16], so in this study we reported only intra-testing reliability for observed measurement (see below for details)”
RESULTS
Figures 2 and 3: in the y-axis add the unit of measurement. Above the “*” add the exact p-value and effect size
Response: Added, thank you.
DISCUSSION
Add future research proposes within section 4.5
Response: Thank You for your suggestion. The part of the 4.5. section is rewritten and the text reads: “Therefore, further interventional studies that will be directly aimed toward a reduction of dissimilarity in performances are needed for a more profound interpretation of the evidently complex influence of D/ND symmetry on performance in basketball. Also, the sample of variables should certainly be extended, especially to measures of strength of the lower extremities as it can highly impact manifestation of other motor abilities. Finally, since participants in this study were elite, male, professional basket-ball players in future studies it is necessary to observe positional and performance lev-el differences at other age, gender and playing level groups.”
Add a sub-section of practical implications.
Response: Thank You. Additional sub section is written and it reads: “The results of this study provide guidance to basketball coaches and staff in the process of selecting basketball players and also in organizing the optimal training plan. As mentioned before, cross-sectional character of the study limits possibility for clear conclusions regarding causality between symmetry and player’s performance. However, even if the observed differences in symmetry are consequence of specific training regime, it gives clear guidelines for necessity of unilateral development of specific basketball jumping and agility movements in professional basketball players. Certainly the absolute values achieved on the dominant and non-dominant side will have the greatest impact on performance, but if a player can perform specific tasks in the game on both sides equally efficiently, powerfully and quickly, we can assume that they will be generally more successful.”
Thank you for your suggestions and comments.
Staying at your disposal!
Round 2
Reviewer 3 Report
The article was improved and can be accepted.
