Effects of different tennis racket string tension on forehand stroke effect and racket dynamic impact

Guohui Zhao; Chen Li; Ye Liu

doi:10.1371/journal.pone.0317442

. 2025 Jan 15;20(1):e0317442. doi: 10.1371/journal.pone.0317442

Effects of different tennis racket string tension on forehand stroke effect and racket dynamic impact

Guohui Zhao ^1,², Chen Li ^1,^#, Ye Liu ^1,^*,^#

Editor: Yaodong Gu³

PMCID: PMC11734973 PMID: 39813279

Abstract

This study investigates the effect of varying tennis racket string tension on stroke effect and the dynamic response of the racket. Using the YSV dynamic acceleration signal acquisition system and a portable radar speed gun collect data on racket acceleration, stress-strain signals, and ball speed from 15 male athletes. Stroke accuracy and depth were assessed according to the International Tennis Number. The recorded stroke speeds were 108.87±13.57 km/h, 111.83±16.34 km/h, and 107.76±12.53 km/h for the low, medium, and high tension, respectively. A significantly higher ball speed was observed at 54lbs compared to both 48lbs and 60lbs (P <0.05). Control scores were 4.90±0.61,5.46±0.84, and 4.64±0.69 for the respective tensions. The control at 54lbs was significantly higher than at 60lbs (P<0.05). Deformation measurements were 18.53±4.90με, 16.31±4.42με, and 20.90±3.53με, with significantly lower deformation at 54lbs compared to 60lbs (P<0.05). The impact forces recorded were 381.81±48.51m/s², 380.53±50.47m/s², and 380.04±53.70m/s², with no significant effect of string tension on impact force. Racket vibration frequencies were 44.14±0.48Hz, 44.08±0.35Hz, and 44.14±0.25Hz, with no significant difference among three string tensions. Rackets with three string tensions showed significantly higher vibration frequencies during the collision phase compared to before or after (P<0.01). In conclusion, string tension affect the stroke effect, racket strung at medium tension can optimize stroke effect while got milder dynamic impact, suggesting that racket strung at medium tension is recommended for tennis enthusiasts to enhance stroke performance and to decrease the risk of resonance damage in the forearm soft tissues.

Introduction

The forehand stroke, ranking as the second most vital stroke in tennis [1], is the most commonly executed groundstroke among professional players [2, 3] and typically the initial skill acquired by novice tennis enthusiasts [4]. Mastery of the forehand is essential for maintaining an aggressive playing stance [5]. This stroke constitutes over 25% of all tennis actions and is recognized as a significant indicator of match outcomes [6, 7]. Ball velocity is a paramount determinant of tennis performance, as it limits the opponent’s time to prepare and execute their response [7]. Additionally, ball precision is a critical performance metric in tennis [8], and when combined with optimal ball velocity, it can dictate the success of a rally [7]. The velocity and precision of the ball are the principal determinants of stroke excellence [9].

The tennis racket consists of the frame, handle, and strings [10]. The International Tennis Federation permits manufacturers to modify the racket’s stiffness, weight, balance, and string pattern, which in turn influence the racket’s playing characteristics. Among these factors, string tension plays a crucial role in determining both the playing performance and material characteristics of the racket. Evidence suggests that both professional and amateur tennis players change their string tension before matches or during training in order to minimize the impact of changes in string tension on their shot performance [11].

String tension impacts stroke effectiveness, with racket speed and stroke accuracy being critical determinants of tennis performance [8]. It is commonly believed that within the recommended range of string tension, lower tension results in greater rebound speed [12–16]. However, rackets with lower tension did not produce higher stroke speeds [11]. Conversely, higher tension enhanced ball control, with no significant speed differences between medium and low-tension strings [17]. They also reported varied success rates in strokes across different tensions, with no consistent outcomes. Notably, rackets with a medium tension of 53-pound (235N) showed the highest baseline errors, suggesting no significant correlation between control and string tension [18]. Previous investigations predominantly assessed the effects of string tension on ball velocity within controlled laboratory settings [14, 19–26], where criteria for evaluating control were frequently arbitrary, devoid of objective benchmarks that reflect the players’ actual performance in stroke control [11, 17, 26]. In stark contrast, the International Tennis Number (ITN) rating test stands as a globally acknowledged benchmark for tennis proficiency, delineating precise guidelines for the demarcation of tennis courts and the assessment of stroke control.

String tension also influences the racket’s dynamic response [27]. Research indicates that higher string tension generate more impact vibrations during strokes. The vibration frequency in the holding hand of participants maintaining a stroke posture ranged from 0–120 Hz when the racket was struck at a certain speed [28]. Through analyzing racket frame acceleration during simulated matches, found the vibration frequency of the racket frame to be around 200 Hz [29]. But the racket’s inherent vibration frequency lies between 130–160 Hz [21]. These studies suggest that changes in string tension induce corresponding vibrations in the racket [27], yet they predominantly focused on comparing vibrations of hand-held, freely suspended, or clamped rackets [26, 28–34], neglecting the real-life context of tennis strokes and human participation. They did not analyze the racket’s dynamic response during athletes swinging and stroking processes.

Previous studies on the effects of string tension on stroke effect lack quantitative evaluations, and overlook the human element in real tennis strokes, thus detaching the studies from actual play conditions. Given the significance of forehand strokes [35], this investigation focuses on forehand strokes in conjunction with the International Tennis Number(ITN). The study hypothesizes that with increasing string tension, stroke control improves, stroke speed decreases, and racket vibrations increase. The study aims to analyze the impact of string tension variations on stroke control and the characteristics of racket vibrations during strokes. The goal is to provide tennis enthusiasts with more informed recommendations on string tension selection.

Methods

Participants

Fifteen male students specializing in tennis at Beijing Sport University, all of whom are right-handed, were recruited for this study. None of the participants had a history of injury within the six months preceding the tests, and none engaged in intense physical activity during the week before the tests. After providing written informed consent, their information was recorded and is presented in Table 1. All procedures were conducted in conformity with the Declaration of Helsinki and were approved by the Ethical Review Board of Beijing Sport University Sports Science Experiment Ethics Committee (2021060H).

Table 1. The participants information.

Number of Participants	Gender	Age (years)	Height (cm)	Weight (kg)	BMI (kg/m²)	Expertise (years)	Training per Week (hours)
15	Male	24.20±0.74	179.00±5.90	71.00±8.58	22.15±2.17	5.36±0.84	29.50±7.77

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Experimental procedures

Before the formal tests, participants were familiarized with the testing procedures under standardized guidance. Formal Testing: Participants stood at the baseline of a standard tennis court (23.77meters long and 8.23meters wide) and, using their preferred stance, hit the ball with maximum effort using a forehand stroke directed cross-court, each to each performed three sets of tests, with a 15-minute rest period between each set. Before each set, participant performed two practice strokes, followed by six test strokes. All forehand stroke were executed using a semi-Western grip with maximum force. Racket acceleration, stress-strain signals, ball speed, and scoring were recorded.

The tennis court was divided into specific zones (Fig 1) according to the International Tennis Number (ITN), and ball landing spots were recorded based on ITN. Throughout the experiment, every participant used rackets with string tension of 48lbs, 54lbs, and 60lbs [11, 22, 29, 36] in a randomized order for the three sets, coach delivered the balls the in sync with the participants hitting rhythm though self-made, simple ball-feeding device(Fig 2), positioned as shown in Fig 1. Ball speed was measured using a portable radar speed gun that’s supported by a triangular bracket at 3.50meters from baseline (Stalker Pro II, Stalker Radar, Plano, Texas, USA). An 8-channel YSV8008 acceleration acquisition system (Beijing Yiyang Strain and Vibration Testing Technology Co., Ltd., China, sampling rate: 2048 Hz) and a YSV2303S accelerometer (Beijing Yiyang Strain and Vibration Testing Technology Co., Ltd., range: ±100g, sampling rate: 2048 Hz, weight: 18g) recorded the racket’s impact during strokes. Racket deformation was measured using BX120-2AA stress-strain gauge. The placement of the accelerometer and stress-strain gauge is shown in Fig 3. The tests utilized tennis racket (Wilson k tour 95), TELOON tennis balls, and racket strings with a diameter of 1.15 mm polyester. The portable radar speed gun was positioned 3.50 meters from the baseline and 3.30 meters from the singles sideline (Fig 1). The self-made ball-feeding device was placed 2.29 meters from the center of the device and 2.30 meters from the singles sideline, as indicated in Fig 1.

Fig 2 — The center of the self-made ball feeding device is located 229cm from the baseline and 230cm from the singles sideline. The height of the ball entrance end from the ground is 246cm, while the height of the ball exit end from the ground is 194cm. The ball exit end is 111cm from where the ball lands.

Fig 3 — (a) The placement of the accelerometer, (b) The placement of stress-strain gauge.

Data processing

In this study, an accelerometer was used to collect the variation of acceleration along the Z-axis, perpendicular to the racket face, during forehand strokes. This measurement reflects the maximum impact force exerted on the racket in the vertical direction during the stroke. All experimental data processing was based on valid strokes. The stroke control score was derived by referencing the depth and accuracy scores from the International Tennis Number (ITN).

The YSV data acquisition system applied a 20–220 Hz bandpass Butterworth filter to the data recorded by the accelerometer [37]. The vibration frequency of the racket before, during, and after the stroke, as well as the maximum strain signal during the stroke, were calculated. The average values of the data from each participant’s valid strokes were used as the final data. Data processing and statistical analysis were performed using custom-written MATLAB scripts (The MathWorks Inc., USA) and SPSS 17.0 (SPSS Inc., USA). The Pauta criterion was used to exclude outliers from the data set if their deviation from the mean exceeded twice the standard deviation. After removing these outliers, paired T-tests were conducted. Pearson correlation analysis was employed to examine the relationships among the data. The results were presented as mean ± standard deviation (M±S). Statistical significance was defined as a type I error probability not exceeding 0.05.

Results

Impact of different string tension on the effect of stroke

In terms of ball speed, the racket strung at 54lbs produced the highest speed, followed by the racket strung at 48lbs, with the racket strung at 60lbs producing the lowest speed. There was no significant difference in ball speed between the 48lbs and 54lbs rackets (P = 0.036). Similarly, there was no significant difference in ball speed between the 48lbs and 60lbs rackets (P = 0.977). However, there was a significant difference in ball speed between the 54lbs and 60lbs rackets (P = 0.014). Thus, the highest ball speed was achieved with the 54lbs racket, followed by the 48lbs racket, and the lowest ball speed was achieved with the 60lbs racket.

Regarding the score of control, there was no significant difference between the 48lbs and 54lbs string tension (P = 0.161), nor between the 48lbs and 60lbs string tension (P = 0.073). However, there was a significant difference in control scores between the 54lbs and 60lbs string tension (P = 0.012). The analysis indicates that different string tension can impact stroke control, with the 54lbs string tension providing the best control score, which is higher than both the 48lbs and 60lbs tension.

The influence of different string tension on racket impact force

When the string tension is 48lbs, the resulting peak acceleration does not significantly differ from the peak accelerations produced at string tension of 54lbs and 60lbs (P = 0.468, P = 0.451). Similarly, there is no significant difference in the collision acceleration during impact between rackets strung at 54lbs and those strung at 60lbs (P = 0.390). The deformation of the racket at 48lbs during ball impact does not significantly differ from the deformation at 54lbs and 60lbs (P = 0.103, P = 0.908). However, there is a significant difference in the amount of deformation between string tension of 54lbs and 60lbs (P = 0.018). The string tension results in the racket experiencing essentially the same impact load, yet the deformation varies with different string tension. Specifically, the deformation is minimal at 54lbs, followed by 48lbs, with the greatest deformation occurring at 60lbs.

Effect of different string tension on the vibration frequency of racket

Before the collision, the vibration frequencies generated by rackets with different string tensions showed no significant differences (P > 0.05). However, during the collision, the vibration frequencies increased significantly across all tensions levels due to the impact (P < 0.01), with no significant differences between the different tensions groups (P > 0.05). In the follow-through phase after the collision, the vibration frequencies of rackets with different tensions rapidly decayed back to the pre-collision levels, again with no significant differences between the tension groups (P > 0.05).

Discussion

By studying the impact of string tension variations on stroke effect and the dynamic response of the racket, the following key findings were observed: string tension significantly affects both ball speed and control. The 54lbs string tension resulted in the highest ball speed and best control, followed by 48lbs and 60lbs, string tension has minimal effect on the racket’s dynamic impact force and vibration. However, it significantly influences racket deformation, with the greatest deformation occurring at 60lbs, followed by 48lbs, the least deformation at 54lbs.

Effect of different string tension on stroke effect

The tension of tennis racket strings significantly impacts ball speed. The ball speed generated with a 54lbs string tension is greater than that with a 60lbs tension, and this difference is statistically significant (Table 2). This conclusion aligns with the findings that lower string tension results in faster ball speeds [11, 17, 38]. From an energy perspective, when the ball collides with the racket strings, kinetic energy is converted into elastic energy, which is evenly distributed between the racket and the ball [39, 40]. The elastic energy stored in the strings accounts for approximately 95% of the total elastic energy [41], while the energy stored in the tennis ball itself accounts for 5% [42]. The ball utilizes 55% of its own stored elastic energy [41], with more elastic energy being stored in the strings. Consequently, changes in energy distribution after the collision have a more significant impact.

Table 2. Influence of different string tension on ball speed.

Group	N	Ball speed (km/h)	Score of control
48bl	46	108.87±13.57Δ	4.90±0.61
54bl	41	111.83±16.34	5.46±0.84
60bl	49	107.76±12.53Δ	4.64±0.69Δ

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Note: “Δ” indicates a significant difference (P < 0.05) to stroke the ball with a string tension of 54lbs.

Consistent with the results of this study, lower string tension leads to greater deformation of the strings and smaller deformation of the ball, resulting in lower overall energy consumption by the ball [13]. When the ball collides with higher string tension, it undergoes greater deformation, resulting in higher energy consumption [21, 24]. Since the total energy remains constant during the collision, greater string deformation corresponds to higher energy storage and more energy transferred back to the ball, resulting in faster ball speed. Therefore, lower string tension produces faster ball speeds compared to higher string tension. The rebound coefficient, representing the ratio of the velocity after collision to the velocity before collision between the ball and the racket face, is highest for rackets with lower string tension [16]. The increased rebound coefficient associated with lower tension is believed to be due to the trampoline effect of the racket. Lower string tension leads to a greater trampoline effect, causing more significant deformation of the racket string bed and storing more energy, thus increasing the energy transferred to the ball and explaining the reason for higher ball speeds at lower tension [43]. To substantiate this perspective, the study findings that demonstrate the most significant reduction in ball speed ratio. (vector sum of the pre-collision and post-collision ball speeds divided by the pre-collision speed) occurs at a string tension of 250N (approximately 56lbs), with a decrease observed when the tension is lower or higher than 250N [13]. The relationship between ball speed and string tension in this study further confirms a sinusoidal function.

In terms of ball control, string with a moderate tension of 54lbs provide better control during ball impact compared to a higher tension of 60lbs, and this difference is statistically significant. The results of this study are consistent with the findings that moderate string tension result in better success rates for racket-ball impact [17], in contrast to the research [11, 44]. Laboratory studies have also indicated that higher string tension improves ball control, while lower string tension allows for higher ball speeds [14]. However, this relationship is effective only when the tension is approximately 40lbs or higher [22]. Lower string tension allows for faster ball speeds [13], whereas higher string tension favors ball control [17]. The results of this study suggest that string tension between low and high levels provide better ball control during impact.

Dynamic impact of different string tension on tennis rackets

The effect of different string tension has been extensively investigated. Varied string tension can alter the stiffness of the racket materials, leading to different deformations when subjected to forces. The impact force experienced by the racket during a stroke is generated by the ball collision with the strings [22, 45]. The deformation of the racket results from the collision between the ball and the string bed. Acceleration data of the racket is related to the initial impact, and the maximum load, as well as tissue stress and strain, are influenced by the initial impact load [46]. However, the variation in string tension does not significantly affect the magnitude of the impact force on the racket face during low, medium, or high string tension strokes, with an average peak force of approximately 380N. This phenomenon is due to the increase in the racket trampoline effect caused by lower poundage, resulting in greater deformation of the racket face [43]. This theory can explain why the racket deformation differs despite the same applied force on the string bed in this study. Compared to the two relatively lower tension strings, the 60-pound tension string exhibits a lower trampoline effect and lesser cushioning, leading to larger deformation of the racket itself (Table 3). On the other hand, both medium and low string tension can generate a strong trampoline effect, resulting in similar deformations of the racket. The analysis suggests that different string tension lead to variations in the deformation of the racket caused by the collision between the ball and the strings. Higher string tension can cause greater deformation of the racket, potentially impacting control over the ball. This is supported by the findings of this study, where the 60-pound group demonstrated lower stroke control scores compared to the 48-pound and 54-pound groups, while the 54-pound group with the smallest racket deformation showed the highest stroke control scores (Table 2).

Table 3. Influence of different string tension on peak acceleration in the vertical racquet face direction.

Group	N	Peak acceleration (m/s²)	Racket strain (με)
48bl	46	381.81±48.51	18.53±4.90
54bl	41	380.53±50.47	16.31±4.42
60bl	49	380.04±53.70	20.90±3.53Δ

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Note: “Δ” indicates a significant difference (P < 0.05) compared to the deformation parameter of the racket when stroke the ball with a string tension of 54lbs.

In addition to the materials and structural characteristics of the racket itself, the influence of hand grip cannot be ignored in the dynamic performance of the racket [47]. During a stroke, the interaction between the racket and the arm alters the racket dynamic performance, as it experiences the impact of the ball colliding with the strings as well as the racket vibration [48]. The vertical vibration of the racket face reflects its performance [37], with the majority of vibration frequencies ranging from 80 to 300 Hz. Throughout the entire stroke process with three different string tension, the vibration frequency is highest during collision but still lower compared to static and simulated tests, averaging only around 44 Hz (Table 4). Moreover, the vibration frequency of the racket quickly decays to pre-collision levels after the stroke, as the vibration energy transfers to the forearm [48], triggering active contraction of the forearm muscles [49] and changes in the dynamic viscoelasticity of the forearm soft tissues [48]. These variations in the forearm soft tissues help avoid resonance damage by shifting the vibration frequency away from the racket vibration frequency during the stroke.

Table 4. Influence of different string tension on vibration frequency of the racket during stroke.

Group	N	Vibration frequency (Hz)
Group	N	Before collision	During collision	After collision
48bl	46	39.76±1.23	44.14±0.48ΔΔ	39.45±0.96##
54bl	41	40.59±1.30	44.08±0.35ΔΔ	39.54±1.36##
60bl	49	39.77±0.81	44.14±0.25ΔΔ	39.05±1.08##

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Note: “ΔΔ” indicates a significant difference (P < 0.01) compared to the racket vibration frequency before the collision, “##” indicates a significant difference (P < 0.01) compared to the racket vibration frequency during the collision.

This study investigates the effects of string tension on both stroke efficacy and the dynamic behavior of tennis rackets under actual playing conditions. Within the acceptable tension parameters, 54-pound strings were found to yield greater ball velocity and enhanced control during play, with negligible impact on the racket dynamic performance. The soft tissues of the upper limb actively respond, mitigating resonance and consequently diminishing the likelihood of forearm injuries. This is particularly evident as the racket undergoes minimal deformation upon ball impact when the force of impact is relatively constant. Thus, for players and coaches, selecting a medium string tension within the racket permissible range is beneficial not only for improving stroke effect but also for minimizing the risk of arm injuries due to vibrations and impact forces during play. For racket manufacturers, it is recommended to optimize the racket’s trampoline effect to absorb the impact load during the stroke, which can reduce the incidence of forearm injuries and the development of tennis elbow.

This study has several limitations, including the omission of grip strength and stroke position measurements, both of which are known to affect racket vibrations and impact forces. To address this, we utilized a custom-designed ball-feeding device to standardize ball speed and simulate realistic stroke scenarios. Intermediate-level players were involved to minimize variability associated with these factors. Data analysis was performed using paired sample comparisons to minimize biases arising from individual differences. The scope of the research was confined to a single racket brand and three specific string tension. Future research is intended to include a variety of brands and a broader spectrum of string tension.

Conclusions

From the perspective of the impact on the racket-arm system, medium string tension generates the highest ball speed and best control during play. Therefore, it is recommended that tennis enthusiasts opt for rackets with medium string tension for optimal stroke performance. Additionally, racket strung at medium tension got milder dynamic impact, suggesting that manufacturers improve the racket’s trampoline effect and provide cushioning to mitigate the loads produced during collisions.

Supporting information

S1 File. Raw data.

(ZIP)

pone.0317442.s001.zip^{(37.7MB, zip)}

Acknowledgments

The authors would like to acknowledge the valuable contribution of all the athletes and researchers who participated in this study.

Data Availability

All relevant data are within the manuscript and its Supporting Information files.

Funding Statement

The author(s) received no specific funding for this work.

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PLoS One. doi: 10.1371/journal.pone.0317442.r001

Decision Letter 0

Yaodong Gu

7 Feb 2024

PONE-D-24-00255Effects of different tennis racket string tension on forehand stroke effect and racket dynamic impactPLOS ONE

Dear Dr. Liu,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

Please submit your revised manuscript by Mar 23 2024 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

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We look forward to receiving your revised manuscript.

Kind regards,

Yaodong Gu

Academic Editor

PLOS ONE

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Additional Editor Comments:

Please put more information in the methods part as reviewer request.

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Partly

Reviewer #2: Yes

**********

2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

**********

3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

**********

4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

**********

5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: Dear Author/s,

the Author/s did a good job in writing a readable manuscript. This paper could be considered qualified to be published on Plos One if the authors apply the modifications requested, "Major issues" are recommended. It is the reason why "Major revision" is my personal choice. I would be happy to review a revised version of this manuscript.

The aim of the submitted manuscript was to control explore the impact of changes in tennis racket string tension on hitting performance and racket dynamic response.

This paper could be considered qualified to be published if the authors apply the modifications requested.

While it is a very interesting topic, some suggestions for improving the paper are provided below:

• The basic descriptive level adopted by author(s) does not seem compatible with interests of both researchers' conceptual challenges and coaches' practical applications to training. The main concern refers to the weak/absent theoretical background; there is no perceivable research question or rationale for the study presented to readers.

Author(s) do not consider any specific difficulties or other aspects of performing these different types of tennis techniques to minimally justify the comparison; on the other hand, the use of the descriptive knowledge obtained from the observed differences was not discussed in terms of applications for athletes and coaches. In short, the manuscript is limited to a laboratory exercise to partially describe the participants' movement.

• Introduction. Line 71: the Aim of the study has to be included at the end of the Introduction section.

• Subject and Methods. Line 74: more detailed information about participants have to be included in this section (mean values and standard deviation): age, weight, eight, handedness, expertise (years), hours of training per week, etc.

• Line 86. A portable radar speed gun was employed. Details about it have to be reported in the manuscript: brand, model, etc.

• Figures 1 and 2 don’t reach a minimum standard of quality. The two pictures need to be removed from the paper and replaced by high quality pictures or figures/drawings.

• Line 83-85: there are many typing errors.

• Line 95: a feeding machine was used in the present investigation. The brand needs to be specified.

• The balls were dropped by a feeding machine in a specific area of the tennis court. This area has to be described by Authors.

• Line 97: information about target area (dimension and position) can not totally excluded from the paper. I would suggest to include a figure about the set-up.

• Line 102: the subjects randomly used 48-54-60 lbs string tension. Authors have to justify this decision and support it by references.

• Line 102. There are errors about unite of measure.

• Line 126: more details about “YSV data acquisition system” have to be included in the present section.

• Line 139-139. The title of the sub-section needs to be modified. Indeed, “stroke effect” seems not to describe the date present in the Table 1.

• Discussion: a Limits of the study section needs to be included in the present investigation.

• Discussion: some practical applications have to be reported at the end of the manuscript.

• Line 261-262. This sentence has to be removed from the Conclusion and included in the Methods.

Finally, this manuscript could be considered qualified to be published if the authors apply the previous modifications, therefore “Major revision” is recommended.

Reviewer #2: Thank you for the opportunity to review this unique study outlining tennis racket string tension. Overall, this manuscript is well-written, stating that the paper is interesting and correctly prepared.

The following are editing suggestions:

1.In the abstract part, methods, it is essential to add the something about statistical analyses.

2.In the abstract part, results, main findings are needed to show and combine in this part.

3.In the intro part, the first paragraph, “The tennis racket is a complex system composed of the frame, handle, and strings” It is recommended that add some relevant references here.

4.In the intro part, display the aim of this study rather than the necessary and hypothesis.

5.In the methold part, the method is well-structured, with a clear and correct development of sections. It is better to add a figure of experimental set-up which includes participant, racket, net and other necessary equipment.

6.In the results part, tables included in the paper are clear, and there is extensive notes accompanying them. This suggests that the visual representations are effective in conveying information. However, the content of the results text is too short, try to add some details in order this section entirely.

7.In the discussion part, the authors should display the limitations of their study,which is appropriately discussed in the end.

**********

6. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

Reviewer #2: No

**********

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PLoS One. 2025 Jan 15;20(1):e0317442. doi: 10.1371/journal.pone.0317442.r002

Author response to Decision Letter 0

1 May 2024

Responds to the reviewers’ comments:

Reviewer #1:

General comments：

Comment 1: the Author/s did a good job in writing a readable manuscript. This paper could be considered qualified to be published on Plos One if the authors apply the modifications requested, "Major issues" are recommended. It is the reason why "Major revision" is my personal choice. I would be happy to review a revised version of this manuscript.The aim of the submitted manuscript was to control explore the impact of changes in tennis racket string tension on hitting performance and racket dynamic response.This paper could be considered qualified to be published if the authors apply the modifications requested.

Response 1: We appreciate the reviewer for the favorable analysis of our original submission and for highlighting the significance of our studies.

Comment 2: The basic descriptive level adopted by author(s) does not seem compatible with interests of both researchers' conceptual challenges and coaches' practical applications to training. The main concern refers to the weak/absent theoretical background; there is no perceivable research question or rationale for the study presented to readers. Author(s) do not consider any specific difficulties or other aspects of performing these different types of tennis techniques to minimally justify the comparison; on the other hand, the use of the descriptive knowledge obtained from the observed differences was not discussed in terms of applications for athletes and coaches. In short, the manuscript is limited to a laboratory exercise to partially describe the participants' movement.

Response 2: Thank you for your review comments. We have revised the introduction according to your suggestions. The first paragraph of the introduction now presents the research background, emphasizing the significance of string tension in impacting the effectiveness of the stroke and the dynamic response of the racket. The second and third paragraphs discuss the current research on the effects of string tension on the stroke outcome and the state of research on racket dynamics in terms of impact and vibration, as well as the shortcomings in these areas. The fourth paragraph summarizes these issues, noting the lack of quantitative control and evaluation standards in terms of stroke effectiveness, and the oversight of human involvement in practical situations in the research on impact and vibration.

In tennis, the forehand stroke is second only to the serve in importance, and forehand techniques can be divided into topspin and flat strokes. The flat stroke, being an important scoring method that requires high control precision, was the focus during our testing process. We asked all participants to use the forehand flat stroke technique to complete the tests, which eliminated the variability that different tennis techniques might introduce. specific difficulties and other aspects of performing these different types of tennis techniques have been discussion in line 300-309 of manuscript.

The article has been expanded to include discussions about the use of the descriptive knowledge obtained from the observed differences in terms of applications for athletes and coaches in line 285-296 of manuscript .

Specific comments:

Comment 1: Introduction. Line 71: the Aim of the study has to be included at the end of the Introduction section.

Response 1: The aim of the study has been included in the line 71-74 of manuscript.

Comment 2: Subject and Methods. Line 74: more detailed information about participants have to be included in this section (mean values and standard deviation): age, weight, eight,handedness, expertise (years), hours of training per week, etc.

Response 2: We are sorry for our unclear descriptions of the Participants , Participants detailed information are included in Table1 in the line 83 of manuscript

Comment 3: Line 86. A portable radar speed gun was employed. Details about it have to be reported in the manuscript: brand, model, etc.

Response 3: We are sorry for our unclear descriptions of the portable radar speed gun ,Details about the radar speed gun has been reported in the line 95-96 of manuscript

Comment 4: Figures 1 and 2 don’t reach a minimum standard of quality. The two pictures need to be removed from the paper and replaced by high quality pictures or figures/drawings.

Response4: According to the requirements of the journal picture, the quality of the picture has been modified. See the attachment for the modified picture.

Comment5: Line 83-85: there are many typing errors.

Response 5: We are sorry for typing errors. The typing errors has been corrected in lines85-87of manuscript

Comment 6: Line 95: a feeding machine was used in the present investigation. The brand needs to be specified.

Response 6: We are sorry for our unclear descriptions of feeding machine ,In order to ensure that the subjects hit the ball with the maximum power of forehand, we used a self-made simple ball feeding device, and adjusted the device to make the ball in the most suitable hitting position, which can effectively avoid the instability of the machine feeding ball. The picture of the device is illustrated in the Fig3.

Comment 7: The balls were dropped by a feeding machine in a specific area of the tennis court. This area has to be described by Authors.

Response 7: We are sorry for our unclear descriptions of where is feeding machine, the specific area of the tennis court is described in the line98-101, which is shown by the triangle in Fig4

Comment 8: Line 97: information about target area (dimension and position) can not totally excluded from the paper. I would suggest to include a figure about the set-up.

Response 8: We are sorry for our unclear descriptions of target area, information about target area is shown in the Fig4

Comment 9: • Line 102: the subjects randomly used 48-54-60 lbs string tension. Authors have to justify this decision and support it by references.

Response 9: The racquet used for testing has a recommended racquet tension of 40-60 pounds, combined with previous studies（Fabre, 2014;Zhao, 2010; Bower, 2007;R.Cross, 2001）. So the 48-54-60 lbs string tension was selected

Comment 10: • Line 102. There are errors about unite of measure.

Response 10: Errors about unite has been corrected in lines 113 of manuscript

Comment 11: Line 126: more details about “YSV data acquisition system” have to be included in the present section.

Response 11: The details about “YSV data acquisition system” included in the line 86-95 of manuscript

Comment 12: Line 139-139. The title of the sub-section needs to be modified. Indeed, “stroke effect” seems not to describe the date present in the Table 1.

Response 12: In the line 139-140, the title of the sub-section was modified to “Impact of different string tensions on the effectiveness of stroke”

Comment 13: Discussion: a Limits of the study section needs to be included in the present investigation.

Response 13: We apologize for the inappropriate discussion here, the Limits of the study was included in the line 301-310 of manuscript

Comment 14: Discussion: some practical applications have to be reported at the end of the manuscript

Response 14: We apologize for the inappropriate discussion here, the practical applications have been reported in line 288-300of manuscript

Comment 15: Line 261-262. This sentence has to be removed from the Conclusion and included in the Methods.

Response 15: Your suggestion is quite reasonable . The sentence in line 261-262 has moved from the Conclusion to line 101-102 in the Methods of manuscript

Response 1: We appreciate the reviewer for the favorable analysis of our original submission and for highlighting the significance of our studies.

Specific comments:

Comment 1 for “Abstract”: In the abstract part, methods, it is essential to add the something about statistical analyses.

Response 1 for “Abstract”: We apologize for the inappropriate description here. statistical analyses was add to line20-21“All data were tested using paired samples T-test with a statistical significance level of P<0.05”

Comment 2 for “Abstract”: In the abstract part, results, main findings are needed to show and combine in this part.

Response 2 for “Abstract”: We apologize for the inappropriate description here. The results and mains findings have been showed and combine in the line 21-35

Comment 1 for “Introduction”: In the intro part, the first paragraph, “The tennis racket is a complex system composed of the frame, handle, and strings” It is recommended that add some relevant references here.

Response 1 for “Introduction”: “The tennis racket is a complex system composed of the frame, handle, and strings” was modified to “The tennis racket is composed of the frame, handle, and strings” . The relevant references is Analysis and experimental research on the mechanical characteristics of tennis rackets

Comment 2for “Introduction”: In the intro part, display the aim of this study rather than the necessary and hypothesis

Response 2for “Introduction”: The aim of the study was displayed in the line 71-74 of manuscript

Comment for “Methold”: In the methold part, the method is well-structured, with a clear and correct development of sections. It is better to add a figure of experimental set-up which includes participant, racket, net and other necessary equipment.

Response for “Method”:The figure of experimental set-up was added in Fig1. Fig2. Fig3 , Also the description of the “Experimental equipment”section has also been modified, The details see the line 85-102 of manuscript

Comment for “Results”: In the results part, tables included in the paper are clear, and there is extensive notes accompanying them. This suggests that the visual representations are effective in conveying information. However, the content of the results text is too short, try to add some details in order this section entirely.

Response for “Results”:The details have been added in the line 144-158,165-176,183-189

Comment for “Discussion”: In the discussion part, the authors should display the limitations of their study, which is appropriately discussed in the end.

Response for “Discussion”: We apologize for the inappropriate description here. The Limits of the study have been displayed in line 301-310, and discussed appropriately

Attachment

Submitted filename: Response to Reviewers.docx

pone.0317442.s002.docx^{(24.4KB, docx)}

PLoS One. doi: 10.1371/journal.pone.0317442.r003

Decision Letter 1

Yaodong Gu

4 Jun 2024

PONE-D-24-00255R1Effects of different tennis racket string tension on forehand stroke effect and racket dynamic impactPLOS ONE

Dear Dr. Liu,

Please submit your revised manuscript by Jul 19 2024 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

We look forward to receiving your revised manuscript.

Kind regards,

Yaodong Gu

Academic Editor

PLOS ONE

Additional Editor Comments:

Better to put the main finding in the discussion.

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #2: All comments have been addressed

Reviewer #3: (No Response)

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

Reviewer #2: Yes

Reviewer #3: Partly

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #2: Yes

Reviewer #3: No

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

Reviewer #2: Yes

Reviewer #3: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

Reviewer #2: No

Reviewer #3: No

**********

6. Review Comments to the Author

Reviewer #2: The revised manuscript is well-written and it is able to be considered to publish. However, some issues have to be modified before publication.

1.The format of cited references in the introduction, such as Zhang W, Jean Bernard Fabre and others, needs to be revised.

2.Do not use "meanwhile" in the research article, it is a colloquial expression.

3.If humans were involved in the study, it is recommended use "participant" not "subject" in the method.

4.All the figures are not only blurry but chaotic background. It is better to change or replace figures.

5.It is feasible to combine the "Experimental equipment" with "Testing method" which could be called "Experimental Procedures".

6.The writing is of poor quality, please proof-read to improve the clarity for reading and understanding.

Reviewer #3: Review comment

This manuscript entitled “Effects of different tennis racket string tension on forehand stroke effect and racket dynamic impact” is encouraging research, but there are several questions that should be addressed before this manuscript can be accepted for publication, which are listed below. You can revise this paper more properly.

Specific comments

1. I suggest optimizing the structure of this manuscript, the format and framework of this manuscript need to be optimized.

2. The format of the abstract part does not meet the specifications and it is recommended to modify it.

3. The citation format of the reference does not comply with the standards of academic articles. It is recommended to modify it.

4. The introduction section lacks the hypothesis of this study. It is recommended to state the problem of this study and add the research hypothesis.

5. The meaning and application of this research should be further and clearly expressed in the introduction section. It will help readers to understand the function and value of this study. Please further explain why have to do this research and the possible benefit of this research to this field.

6. Demographic information on subjects is missing, which is necessary material.

7. In the method section, comprehensive information about the experimental equipment needs to be added in the method section, such as brand, model, company, etc.

8. The title of the figure needs to be placed below the figure.

9. In the Methods section, please add more details and descriptions to complete this part.

10. The experiment is missing a lot of detailed descriptions and process descriptions, which violates the principle of repeatability of the experiment. It is recommended that the description of the method section be re-edited.

11. I suggest adding the key findings at the beginning of the discussion section.

12. The application of key findings in this study should be further mentioned and discussed.

13. The language level of this manuscript needs improvement, and I recommend that the manuscript undergo a thorough grammatical and formatting check.

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #2: No

Reviewer #3: No

**********

Attachment

Submitted filename: Review comment.pdf

pone.0317442.s003.pdf^{(122.9KB, pdf)}

PLoS One. 2025 Jan 15;20(1):e0317442. doi: 10.1371/journal.pone.0317442.r004

Author response to Decision Letter 1

29 Jul 2024

Specific comments:

Comment 1: The format of cited references in the introduction, such as Zhang W, Jean Bernard Fabre and others, needs to be revised.

Response 1: The format of cited references in the introduction has been revised in the line 59-74

Comment 2: Do not use "meanwhile" in the research article, it is a colloquial expression

Response 2: I’m sorry to this error, the mistake has been revised.

Comment 3: If humans were involved in the study, it is recommended use "participant" not "subject" in the method.

Response 3: Your profound language skills are worthy of my learning, and I have made modifications in the line 90

Comment 4: All the figures are not only blurry but chaotic background. It is better to change or replace figures.

Response4: According to your suggestion, we have corrected the figures

Comment5: It is feasible to combine the "Experimental equipment" with "Testing method" which could be called "Experimental Procedures".

Response 5: Thank you for your valuable advice, the "Experimental equipment" with "Testing method" have been calles "Experimental Procedures" in line 102-135

Comment 6: The writing is of poor quality, please proof-read to improve the clarity for reading and understanding.

Response 6: I’m sorry for that, we have improved the writing quality

Reviewer #3: This manuscript entitled “Effects of different tennis racket string tension on forehand stroke effect and racket dynamic impact” is encouraging research, but there are several questions that should be addressed before this manuscript can be accepted for publication, which are listed below. You can revise this paper more properly.

Specific comments:

Comment 1: I suggest optimizing the structure of this manuscript, the format and framework of this manuscript need to be optimized.

Response 1: Thank you for your valuable advice, we have optimizing the structure of this manuscript in the "Abstract","Methods"," Discussion"," References"

Comment 2: The format of the abstract part does not meet the specifications and it is recommended to modify it.

Response 2: I’m sorry for the mistake, the format of the abstract part has been modified in line 37-47, also check the format of the manuscript.

Comment 3: The citation format of the reference does not comply with the standards of academic articles. It is recommended to modify it.

Response3: PLOS uses the reference style outlined by the International Committee of Medical Journal Editors (ICMJE), also referred to as the “Vancouver” style, according to the “Vancouver” style, we modified the citation format of the reference in the line 344-448

Comment 4: The introduction section lacks the hypothesis of this study. It is recommended to state the problem of this study and add the research hypothesis.

Response 4: Thank you for you advise, we added the research hypothesis in the line84-88

Comment 5: The meaning and application of this research should be further and clearly expressed in the introduction section. It will help readers to understand the function and value of this study. Please further explain why have to do this research and the possible benefit of this research to this field.

Response 5: Thank you for your comment, we added the meaning and application of this research in line 85-88, we have explained why have to do this research in line 56-79

Comment 6: Demographic information on subjects is missing, which is necessary material.

Response 6:We have already added demographic information in line 91-101

Comment 7: In the method section, comprehensive information about the experimental equipment needs to be added in the method section, such as brand, model, company, etc.

Response 7: Than you for you comment, we added the comprehensive about the experimental equipment in line 117-128

Comment 8: The title of the figure needs to be placed below the figure.

Response 8: I’m sorry for that, PLOS Manuscript Body Formatting Guidelines in line 32-34 demand that “Each figure caption should appear directly after the paragraph in which they are first cited.” “Figures should be uploaded separately as individual files.” So the figure title and caption can appear in the Manuscript.

Comment 9: In the Methods section, please add more details and descriptions to complete this part.

Response 9: You comment is very important, we have written the Methods in line 91-134

Comment 10: The experiment is missing a lot of detailed descriptions and process descriptions, which violates the principle of repeatability of the experiment. It is recommended that the description of the method section be re-edited.

Response 10: Thank you for your advice, the detailed descriptions and process descriptions have been re-edited in line 103-152

Comment 11: I suggest adding the key findings at the beginning of the discussion section.

Response 11: Thank you for your valuable advice, the key findings has been added at the beginning of the discussion section in line 205-211

Comment 12: The application of key findings in this study should be further mentioned and discussed.

Response 12: The application of key findings in this study should be further mentioned and discussed in line 307-321

Comment 13: The language level of this manuscript needs improvement, and I recommend that the manuscript undergo a thorough grammatical and formatting check.

Response 13: I’m sorry for may poor language of this manuscript, In accordance with your suggestions and the professional polishing team, we have made changes to the grammar and format of the manuscript

Attachment

Submitted filename: Response to Reviewers.docx

pone.0317442.s004.docx^{(20.5KB, docx)}

PLoS One. doi: 10.1371/journal.pone.0317442.r005

Decision Letter 2

Yaodong Gu

12 Aug 2024

PONE-D-24-00255R2Effects of different tennis racket string tension on forehand stroke effect and racket dynamic impactPLOS ONE

Dear Dr. Liu,

Please submit your revised manuscript by Sep 26 2024 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

We look forward to receiving your revised manuscript.

Kind regards,

Yaodong Gu

Academic Editor

PLOS ONE

Additional Editor Comments:

The authors shall check the format of the paper in accordance with journal's requirement.

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

Reviewer #2: All comments have been addressed

Reviewer #3: (No Response)

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

Reviewer #2: Yes

Reviewer #3: Partly

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #2: Yes

Reviewer #3: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

Reviewer #2: Yes

Reviewer #3: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

Reviewer #2: Yes

Reviewer #3: No

**********

6. Review Comments to the Author

Reviewer #2: • The introduction effectively presents the motivation and provides basic information, referring to other publications in the field.

• The publication is well-structured, with a clear and correct development of sections, including abstract, introduction, materials and methods, results, discussion, and conclusions.

• The graphs included in the paper are clear. This suggests that the visual representations are effective in conveying information.

• The authors demonstrate awareness of the limitations of their study, and this is appropriately discussed in the discussion section.

• The overall conclusion is positive, stating that the paper is interesting and correctly prepared. The only suggested improvement is related to the volume of the abstract, which is too long.

• After decreasing the volume of abstract, the paper is suitable for publication.

Reviewer #3: Review comment

Thanks to the author for the revision of the manuscript. There are some comments as

follows:

1. Line 40-42. In my point of view, this conclusion is unconvincing and not seriously.

The ‘stroke performance’ in racket sports usually focuses on the stroke play motions

and the performance of the athletes. However, this study only focuses on the impact

of the racket on the ball’s movement, so the use of "stroke performance" is not

rigorous.

2. In the Line 98-99. ‘.... using a forehand stroke directed cross-court, Each

participant…’ I am confusing about this section, maybe you need change ‘Each’ to

‘each’? Please check this issue of whole article.

3. In the Experimental Procedures section, the details are not enough to repeat this

study. Please mentioned is there a ball machine or a coach to do the serve? If it is a

machine or coach, how do you control the ball’s condition? Such as ball’s speed, fall,

and rotation? Please, add more necessary details.

4. Line 116-127. Please check the format and font of this section. I noticed lots of font

and formatting errors.

5. Line 167-170, There is a space in the line here, but there is no space between

L184-L186, why?

6. Line 107. Please revise the citation format.

7. In the Table 2, 3, and 4, there are some error and formatting errors, please check it.

8. Please check the format and font of whole article again. Because I noticed there are

lots of font formatting errors in the manuscript.

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #2: No

Reviewer #3: Yes: Yuqi He

**********

Attachment

Submitted filename: Review comment.pdf

pone.0317442.s005.pdf^{(117.2KB, pdf)}

PLoS One. 2025 Jan 15;20(1):e0317442. doi: 10.1371/journal.pone.0317442.r006

Author response to Decision Letter 2

30 Aug 2024

Responds to the reviewers’ comments:

Reviewer #2: • The introduction effectively presents the motivation and provides basic information, referring to other publications in the field.

• The publication is well-structured, with a clear and correct development of sections, including abstract, introduction, materials and methods, results, discussion, and conclusions.

• The graphs included in the paper are clear. This suggests that the visual representations are effective in conveying information.

• The authors demonstrate awareness of the limitations of their study, and this is appropriately discussed in the discussion section.

• The overall conclusion is positive, stating that the paper is interesting and correctly prepared. The only suggested improvement is related to the volume of the abstract, which is too long.

• After decreasing the volume of abstract, the paper is suitable for publication.

Response: Thank you for your comments, we decreased the volume of abstract in line 14-39

Reviewer #3: Thanks to the author for the revision of the manuscript. There are some comments as follows:

Specific comments:

Comment 1: Line 40-42. In my point of view, this conclusion is unconvincing and not seriously. The ‘stroke performance’ in racket sports usually focuses on the stroke play motions and the performance of the athletes. However, this study only focuses on the impact of the racket on the ball’s movement, so the use of "stroke performance" is not rigorous.

Response 1: Thank you for your advice, according your view, “stroke performance” was change to “stroke effect” in line 31-32.

Comment 2: In the Line 98-99. ‘.... using a forehand stroke directed cross-court, Each participant…’ I am confusing about this section, maybe you need change ‘Each’ to‘each’? Please check this issue of whole article.

Response 2: I’m sorry for the mistake, we modified this in line 88-89, and check the issue of whole article.

Comment 3: In the Experimental Procedures section, the details are not enough to repeat this study. Please mentioned is there a ball machine or a coach to do the serve? If it is a machine or coach, how do you control the ball’s condition? Such as ball’s speed, fall, and rotation? Please, add more necessary details.

Response3: Before the test, we Before the formal test, we conducted a pre-experiment, adjusted the self-made ball feeding device to ensure the quality of the ball. The self-made ball feeding device is shown in the figure 2, the details description is shown in line 111-117

Comment 4: Line 116-127. Please check the format and font of this section. I noticed lots of font and formatting errors.

Response 4: Thank you for your comment, we revised the format and font of this section in the line104-119. The figure captions in line 111,114,118 use bold type for the figure titles according the manuscript body formatting guidelines.

Comment 5: Line 167-170, There is a space in the line here, but there is no space between L184-L186, why?

Response 5: I’m sorry for the stupid mistake, we correct the mistake and check the hole manuscript

Comment 6: Line 107. Please revise the citation format.

Response 6: Thank you, We have already revised the citation format in line 95-96

Comment 7: In the Table 2, 3, and 4, there are some error and formatting errors, please check it.

Response 7: Thank you for the comment, we revised the error in the Table 2,3,4.

Comment 8: Please check the format and font of whole article again. Because I noticed there are lots of font formatting errors in the manuscript.

Response 8: Thank you for this comment, We check the full manuscript and modified the errors.

Attachment

Submitted filename: Response to Reviewers.docx

pone.0317442.s006.docx^{(19.1KB, docx)}

PLoS One. doi: 10.1371/journal.pone.0317442.r007

Decision Letter 3

Yaodong Gu

24 Sep 2024

PONE-D-24-00255R3Effects of different tennis racket string tension on forehand stroke effect and racket dynamic impactPLOS ONE

Dear Dr. Liu,

Please submit your revised manuscript by Nov 08 2024 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

We look forward to receiving your revised manuscript.

Kind regards,

Yaodong Gu

Academic Editor

PLOS ONE

Journal Requirements:

Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

Additional Editor Comments:

Please check some minor questions raised by the reviewer.

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

Reviewer #2: All comments have been addressed

Reviewer #3: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

Reviewer #2: Yes

Reviewer #3: Partly

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #2: Yes

Reviewer #3: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

Reviewer #2: Yes

Reviewer #3: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

Reviewer #2: Yes

Reviewer #3: Yes

**********

6. Review Comments to the Author

Reviewer #2: After previous issues solved, the present revised manuscript is well-written, and it is able to be considered for publication.

Reviewer #3: There are still some issue about format should be revised. Please check the whole manuscript again, thanks.

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #2: No

Reviewer #3: Yes: Yuqi He

**********

PLoS One. 2025 Jan 15;20(1):e0317442. doi: 10.1371/journal.pone.0317442.r008

Author response to Decision Letter 3

22 Oct 2024

Responds to the reviewers’ comments:

Comment 1:

Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. must be drawn appropriately based on the data presented.

Reviewer #3: Partly

Response：We are sorry for our mistakes. After examining our manuscript, we found there may be some unclear and insufficient descriptions of the results and conclusions, especially in the Abstract section.

Therefore, we enriched our results, and rewrote the conclusions to make them correspond to our results in lines 35-42.

Comment 2:

Reviewer #3: There are still some issues about format should be revised. Please check the whole manuscript again, thanks.

Response：Sorry for the issues about format, and we have made some modifications in the manuscript, such as below:

1) In line 114: the brand of tennis balls used in the test was described more precision and clarity.

2) In Table 4 and lines 190-191: we used more standardized and accurate statistical significance annotation symbols.

3) In lines 322-328: we rewrote the conclusions to make them correspond to our results.

Attachment

Submitted filename: Response to Reviewers.docx

pone.0317442.s007.docx^{(18.8KB, docx)}

PLoS One. doi: 10.1371/journal.pone.0317442.r009

Decision Letter 4

Yaodong Gu

13 Nov 2024

PONE-D-24-00255R4Effects of different tennis racket string tension on forehand stroke effect and racket dynamic impactPLOS ONE

Dear Dr. Liu,

Please submit your revised manuscript by Dec 28 2024 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

We look forward to receiving your revised manuscript.

Kind regards,

Yaodong Gu

Academic Editor

PLOS ONE

Journal Requirements:

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

Reviewer #3: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

Reviewer #3: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #3: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

Reviewer #3: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

Reviewer #3: Yes

**********

6. Review Comments to the Author

Reviewer #3: Thank you for all the edits and adjustments you made to this manuscript. There are still have some issue should be adjust.

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #3: No

**********

Attachment

Submitted filename: Review comment.pdf

pone.0317442.s008.pdf^{(119.4KB, pdf)}

PLoS One. 2025 Jan 15;20(1):e0317442. doi: 10.1371/journal.pone.0317442.r010

Author response to Decision Letter 4

27 Dec 2024

Specific comments

Comment 1:

Reviewer #3: 1. The manuscript mentions that the string tension of a tennis racket has an important influence on playing performance and material properties, but does not elaborate on why string tension is an important area of research. Some background information could be added, such as how string tension affects the performance of professional and amateur players and its importance in the selection of tennis equipment.

Response：Thank you for your comment, we have added the background information in line 58-60.

Comment 2:

Reviewer #3: 2. Please be more specific about why you chose forehand strokes as the subject of your study and why you chose the International Tennis Number (ITN) as the evaluation criterion.

Response：We are sorry for the stupid mistakes, we have explained why you chose forehand strokes as the subject of our study in line 44-53, and Modifications have been made regarding why ITN was chosen as the evaluation standard in line 69-75.

Comment 3:

Reviewer #3: 3. L58-L59, ‘Much of the prior research was conducted under laboratory conditions, lacking objective standards for evaluating stroke control based on participant performance’ …The journal encourages the addition of articles with more recent years. The following literature is encouraged to be cited and referenced: ‘He Y, Fekete G, Sun D, Baker JS, Shao S, Gu Y. Lower Limb Biomechanics during the Topspin Forehand in Table Tennis: A Systemic Review. Bioengineering. 2022; 9(8):336. https://doi.org/10.3390/bioengineering9080336’.

Response：We have add the articles published in recent years, including the article you recommended.

PLoS One. doi: 10.1371/journal.pone.0317442.r011

Decision Letter 5

Yaodong Gu

30 Dec 2024

Effects of different tennis racket string tension on forehand stroke effect and racket dynamic impact

PONE-D-24-00255R5

Dear Dr. Liu,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

An invoice will be generated when your article is formally accepted. Please note, if your institution has a publishing partnership with PLOS and your article meets the relevant criteria, all or part of your publication costs will be covered. Please make sure your user information is up-to-date by logging into Editorial Manager at Editorial Manager® and clicking the ‘Update My Information' link at the top of the page. If you have any questions relating to publication charges, please contact our Author Billing department directly at authorbilling@plos.org.

If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

Kind regards,

Yaodong Gu

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

PLoS One. doi: 10.1371/journal.pone.0317442.r012

Acceptance letter

Yaodong Gu

3 Jan 2025

PONE-D-24-00255R5

PLOS ONE

Dear Dr. Liu,

I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now being handed over to our production team.

At this stage, our production department will prepare your paper for publication. This includes ensuring the following:

* All references, tables, and figures are properly cited

* All relevant supporting information is included in the manuscript submission,

* There are no issues that prevent the paper from being properly typeset

If revisions are needed, the production department will contact you directly to resolve them. If no revisions are needed, you will receive an email when the publication date has been set. At this time, we do not offer pre-publication proofs to authors during production of the accepted work. Please keep in mind that we are working through a large volume of accepted articles, so please give us a few weeks to review your paper and let you know the next and final steps.

Lastly, if your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

If we can help with anything else, please email us at customercare@plos.org.

Thank you for submitting your work to PLOS ONE and supporting open access.

Kind regards,

PLOS ONE Editorial Office Staff

on behalf of

Professor Yaodong Gu

Academic Editor

PLOS ONE

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

S1 File. Raw data.

(ZIP)

pone.0317442.s001.zip^{(37.7MB, zip)}

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Data Availability Statement

All relevant data are within the manuscript and its Supporting Information files.

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PERMALINK

Effects of different tennis racket string tension on forehand stroke effect and racket dynamic impact

Guohui Zhao

Chen Li

Ye Liu

Roles

Abstract

Introduction

Methods

Participants

Table 1. The participants information.

Experimental procedures

Fig 1. Tennis court division and ball feeder location.

Fig 2. Simple ball-feeding device.

Fig 3. The placement of the accelerometer and stress-strain gauge.

Data processing

Results

Impact of different string tension on the effect of stroke

The influence of different string tension on racket impact force

Effect of different string tension on the vibration frequency of racket

Discussion

Effect of different string tension on stroke effect

Table 2. Influence of different string tension on ball speed.

Dynamic impact of different string tension on tennis rackets

Table 3. Influence of different string tension on peak acceleration in the vertical racquet face direction.

Table 4. Influence of different string tension on vibration frequency of the racket during stroke.

Conclusions

Supporting information

Acknowledgments

Data Availability

Funding Statement

References

Decision Letter 0

Yaodong Gu

Roles

Author response to Decision Letter 0

Decision Letter 1

Yaodong Gu

Roles

Author response to Decision Letter 1

Decision Letter 2

Yaodong Gu

Roles

Author response to Decision Letter 2

Decision Letter 3

Yaodong Gu

Roles

Author response to Decision Letter 3

Decision Letter 4

Yaodong Gu

Roles

Author response to Decision Letter 4

Decision Letter 5

Yaodong Gu

Roles

Acceptance letter

Yaodong Gu

Roles

Associated Data

Supplementary Materials

Data Availability Statement

ACTIONS

PERMALINK

RESOURCES

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