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Congratulations on the acceptance of your manuscript. Please add the final edits as requested by reviewer 1
[# PeerJ Staff Note - this decision was reviewed and approved by Mike Climstein, a PeerJ Section Editor covering this Section #]
**PeerJ Staff Note:** Although the Academic and Section Editors are happy to accept your article as being scientifically sound, a final check of the manuscript shows that it would benefit from further editing. Therefore, please identify necessary edits and address these while in proof stage.
Change "players" to "athletes" please. Next revision will be negative due to this concern
revisions accepted
revisions accepted
The reviewers are mostly positive about the changes. Before we proceed with the next steps, the remaining comments from Reviewer 1 should be addressed
Given the context of combat sports, “athletes” (or “fighters” where appropriate) is the correct term and should be used consistently. Please replace “players” with “athletes” throughout the text (and title), including in the title or section headings if any still use the former term. Similarly, the term “core strength training” should be used consistently; in a few places, the manuscript mentions “core stability training” or simply “core training.” If these terms are meant to be synonymous, standardize to one term or clearly define the difference.
Similarly, the same combat sport is referenced with different terms: “Sanda players” (line 218) vs “Sanshou players” (line 344) refer to the Chinese kickboxing discipline – this should be unified to one term. Additionally, the manuscript sometimes says “technical skill performance” (title) but also uses “fighting skill” (line 35)
"By November 2023, consider using well-known academic databases to search for relevant literature, including SCOPUS, PubMed, Web of Science, EBSCO, CNKI databases (note: Only core academic journals were searched), and Searching engine Google Scholar (via EBSCOhost) - remove *well-known*
Line 30: “Only core academic journals were searched in databases.”
Remove the extra “databases.”
Lines 31–32: “…and Google Scholar (via EBSCOhost) Searching engine.”
Change “Searching engine” to “search engine.”
Line 212-214: “8 study participants who met the inclusion criteria” – This is misleading, as eight studies (articles) were included, not 8 individual participants. It should read “8 studies met the inclusion criteria…” since line 214 explicitly says “eight articles.”
Line 222-224: “five of the papers were conducted by researchers over 18, and the remaining three were conducted by researchers under the age of 14” – This sentence is incorrect and confusing. It appears to be referring to participant age groups in the studies (adults vs. youth participants), not the age of the researchers. It should be rewritten (e.g., “five of the studies involved participants over 18 years old, and three studies involved participants under age 14”).
Line 220-222: “the remaining 60 were not reported in the sex binomial study” – The phrase “sex binomial study” is unclear. It seems to mean that for 60 participants, sex was not reported (in certain studies, Pang et al., 2023, and Xiao et al., 2023). This should be clarified, e.g., “and for 60 participants, the sex was not reported by the study.”
The in-text citation style is inconsistent. In some places, the same source is cited in different ways. For example, Xiao and He (2023) appear as “Xiao & He (2023)” in lines 257-258, but the same study is cited as “Xiao et al., 2023” in line 222. If the reference has only two authors, the “et al.” form is incorrect – it should consistently be “Xiao & He (2023)” in all instances. Likewise, Kabadayi et al. (2022) are correctly cited in line 216, but appear with an extra comma as “Kabadayi, et al., 2022” in line 241.
Lines 149–150: “Strategic search queries by title and abstract for each database.”
This is a fragment—no verb.
Rewrite as, e.g., We performed strategic search queries by title and abstract in each database.
In line 212, the description refers to “8 study participants” (which should be “8 studies” as noted above). Ensure the table caption and description accurately reflect the content (likely the characteristics of the 8 studies and their participants).
In lines 30-31 (Methods), the authors note “Only core academic journals were searched” in some databases (e.g., CNKI). This is a minor point, but it should be clarified so that readers understand any exclusions (does this mean non-academic or predatory journals were excluded, or that only high-tier journals in CNKI were considered?). Clarifying any such filter will help others reproduce the search strategy exactly.
While the title mentions "striking sports," the search strategy covers judo and wrestling. - authors need to clarify - the manuscript is about combat sports (grappling + striking) or striking only
Lines 198–207:
826 identified - 804 after duplicates - “leaving 340 articles” after excluding four categories that sum to 252 (40 + 11 + 201), but no count given for “articles not published in journals.”
Provide the exact number excluded as “not published in journals” (e.g., “X articles”), and ensure 804 – (X + 40 + 11 + 201) = 340. Update Figure 1 accordingly.
The use of a risk-of-bias tool is mentioned, but there is a minor concern here. The manuscript states that the Cochrane Risk of Bias tool was used to assess the quality of the included randomized controlled trials (lines 192-193). This implies that for any non-randomized studies included (the criteria allowed “non-randomised research trials,” line 175), a different assessment or criteria might be needed. It is unclear how many of the 8 included studies were RCTs versus non-RCTs. If some included studies were quasi-experimental or single-group designs (as allowed by the inclusion criteria), the authors should also evaluate their quality (perhaps using a tool like ROBINS-I for non-randomized studies) or at least comment on their potential biases.
The manuscript should clarify who assessed the risk of bias and how disagreements were resolved, similar to what was done for study selection and data extraction. For example, did two reviewers independently apply the RoB tool to each study? This is a minor detail, but reporting it (if not, it could be added) would complete the picture of rigorous methodology.
Lines 444–449: “There is evidence that core strength can effectively reduce fatigue accumulation in players, helping them maintain performance…”
No included study measured fatigue or injury outcomes.
Remove or rephrase as a theoretical implication rather than a conclusion.
Lines 248–254, Lines 292–300: Reporting of “impact force” and “impact velocity” lacks units (e.g., Newtons, m/s).
Append units after each numeric outcome (e.g., “2539.3 ± 89.1 N vs 3093.7 ± 69.4 N”).
Methods section (after line 156) and Results: No statement on why a meta-analysis was not performed.
Add a sentence such as, “Due to heterogeneity in outcome measures and reporting formats, a quantitative meta-analysis was not feasible.”
One aspect that is not discussed is the risk of bias of the included studies. The authors generated Figures 2 and 3 for the risk-of-bias assessment, but the text does not explicitly state how many studies were judged to be at high or low risk of bias, nor does it temper any findings based on study quality. If some studies had methodological weaknesses (e.g., lack of randomization or control group, high risk of bias in blinding or outcome assessment), the authors should mention this in the discussion. For instance, a statement could be added such as: “X of the 8 studies were randomized controlled trials with generally low risk of bias, while the others were pre-post designs which inherently have a higher risk of bias; therefore, results, especially from the non-randomized studies, should be interpreted with caution.”
The heading “Discussions” at line 314 should likely be “Discussion” (singular). This seems to be a minor typo, but fixing it will meet conventional formatting.
Ensure consistency in heading formatting and numbering (if any). For example, “Practical application” (line 461) might be better labeled as “Practical Applications” or “Practical Implications” (plural), but this is stylistic – choose one.
The manuscript would benefit from a final proofreading pass to catch any remaining typographical errors and to ensure the writing is as concise as possible. For example, in line 229-230, the phrase “core strength training is the primary intervention means. Core strength training is the primary intervention modality…” is repetitive; this could be simplified to avoid back-to-back identical statements. Cleaning up such redundancies will improve readability.
The authors have made significant improvements in this revision, addressing many concerns from the previous round. I encourage the authors to implement these final revisions, after which the manuscript should be suitable for publication.
The authors have thoroughly addressed all language-related revisions I previously indicated. Grammatical and syntactic issues (e.g., lines 23, 51, 126, 358) have been corrected, and the repetitive use of terms such as “static and dynamic core training” has been reduced for improved readability. Additionally, advanced language editing has been applied throughout the manuscript to enhance academic clarity. The manuscript is now linguistically suitable for publication.
The authors have successfully addressed the concerns regarding methodological limitations. They acknowledged the limited number of included studies and discussed their impact on generalizability. The heterogeneity in intervention protocols and outcome measures was clearly outlined, and its influence on the overall findings was critically evaluated. Additionally, the limitations stemming from the predominance of pre-post designs over randomized controlled trials were transparently discussed, with appropriate caution reflected in the interpretation of results.
The authors have effectively addressed the methodological recommendations. A formal risk of bias assessment was incorporated using the Cochrane RoB tool, enhancing the methodological rigor of the review. While a meta-analysis was not conducted, the authors have now provided a clear and justified explanation regarding its infeasibility due to high heterogeneity among the included studies. Additionally, the variability and limitations of the measurement tools, particularly the use of subjective metrics, have been acknowledged and critically discussed in the revised manuscript.
Following a detailed evaluation of the revised manuscript titled "Effects of Core Strength Training on the Technical Skill Performance of Striking Combat Sport Players: A Systematic Review," I have reviewed the authors' responses to the revision requests and examined the updated manuscript accordingly. I am pleased to report the following:
1. Language and Clarity Improvements:
The authors have addressed the noted grammatical and syntactic issues in the specified lines (23, 51, 126, and 358), significantly improving the clarity and flow of the manuscript. The revised sections now reflect an appropriate academic tone and language quality suitable for publication.
2. Risk of Bias Assessment:
A structured risk of bias evaluation using the Cochrane RoB tool has been properly incorporated for randomized controlled trials. This addition enhances the methodological rigor of the review and aligns with current standards in systematic review reporting.
3. Expanded Comparative Discussion:
The discussion section has been sufficiently expanded to include a more nuanced comparison of static versus dynamic core training effects, particularly within the context of Muay Thai. This addition adds valuable depth to the interpretation of findings.
4. Table Reformatting:
Table 1 has been revised for improved clarity, including the use of abbreviations and column grouping. This reformatting has made the data presentation more reader-friendly without compromising the content.
5. Practical Applications Section:
The section has been enriched with more concrete and actionable recommendations based on the reviewed studies, enhancing the translational value of the findings for coaches, athletes, and practitioners in the field.
The authors have made the necessary changes.
The authors have made the necessary changes.
The authors have made the necessary changes.
The authors have significantly improved the paper.
Overall, the reviewers agree on the relevance of the topic. However, all of them raised serious concerns that include the compatibility of the reported results in the context of the included studies. Please make sure that you adapt the manuscript accordingly
**PeerJ Staff Note:** Please ensure that all review, editorial, and staff comments are addressed in a response letter and that any edits or clarifications mentioned in the letter are also inserted into the revised manuscript where appropriate.
The manuscript conforms to the standard sections expected in a systematic review, including a clear title, abstract, introduction, methods, results, discussion, conclusion, and references. The overall organization facilitates a logical progression of ideas. While the structure generally adheres to the Instructions for Authors, a few formatting inconsistencies, such as duplicated page headers and minor irregularities in section transitions, could be streamlined for enhanced clarity. The manuscript includes relevant visual elements (e.g., Figure 1 and Table 1) that support the content. The figures and tables appear appropriate to the subject matter, providing key data and summarizing essential aspects of the study design and outcomes.
The introduction explains the role of core strength in combat sports, discussing its importance in stabilizing the body, transferring power, and enhancing performance in various technical skills (e.g., kicking, punching). This establishes a clear connection between core strength and the athletic demands of combat sports. Relevant prior literature is referenced throughout the introduction, including seminal works by Guttmann (2004) and Campos (2017), as well as studies that focus on the biomechanics and physiological aspects of combat sports. These references provide a solid foundation and indicate that the study is grounded in established research.
The manuscript is not fully self-contained, as some critical data and study details are missing or inconsistently reported. Notably, it states that 8 publications were included in the systematic review.
But the text then names more than eight distinct studies. For example, Pang et al. (2023) and Xiao et al. (2023) are both discussed as included studies, even though only eight were supposed to meet the criteria. This numerical discrepancy creates confusion about the actual scope of the review. There are also instances of misidentification: one included study by Martins et al. (2019) is described as involving “Taekwondo athletes”, whereas the reference indicates it was a judo athlete study. Similarly, a Muay Thai study is cited in text as “Benjamin & Stuart (2017), yet no such author names appear in the reference list (the Muay Thai study is listed under Lee & McGill, 2017). These inconsistencies suggest the included studies are not clearly or accurately documented, undermining the manuscript’s self-contained nature and making it hard for readers to verify the evidence base.
1. The title uses “Combat Sport Players,” yet elsewhere the manuscript frequently refers to “combat sports” and “combat sports athletes.” Given that “players” is more commonly associated with team sports, while “athletes” is preferred for individual sports such as those in combat disciplines, it is advisable to standardize the terminology.
2. The description of the literature screening contains conflicting numbers. The manuscript states that a pool of 826 articles was identified, with 804 remaining after duplicates were removed. It then indicates that a second round of filtering reduced the number to 212, yet later it reports that 340 full-text articles were assessed for eligibility. This discrepancy in numerical reporting can confuse readers.
3. In the “Search Strategy” section, the phrase “By November 2023, consider using well-known academic databases to search for relevant literature…” appears to be written in a suggestive tone rather than as a definitive description of the methods employed. This wording creates ambiguity about whether the statement is a directive or a factual account of the search process.
4. LL 246 - The latter clause is missing a verb (e.g., “improved”), which renders the sentence incomplete.
5. As previously noted, the title refers to “Combat Sport Players,” while the body of the text variably uses “combat sports athletes” and “fighters.”
6. The introduction references relevant studies; however, it does not explicitly highlight the specific gaps or controversies in the literature that this review intends to address. A clearer articulation of how previous research is limited or contradictory would strengthen the rationale for the study.
7. The background does not sufficiently discuss the theoretical models or mechanisms underlying core strength training and its impact on technical performance. Integrating relevant theories (e.g., motor control, biomechanics) could offer a more comprehensive understanding of how core stability translates into improved athletic performance.
8. The PRISMA flow chart currently contains typographical errors and visible red highlights, which detract from its professional presentation. It is recommended that the authors reupload a corrected version of the PRISMA flow chart with appropriate formatting and resolution
9. Comment 8 also applies to Table 1
1. The topic – sports science/exercise physiology in combat sports – falls under the biological and health sciences domain (sports medicine/kinesiology) that the journal covers. There’s no doubt that the subject matter (training interventions to improve athletic performance) is within the journal’s broad scope. In the introduction, they note that many studies underscore core strength’s importance, but mostly for general athletic performance rather than combat sports’ specific skills. This establishes a rationale for the review without making grandiose claims of being “first” or “revolutionary.” The tone is factual and focused on contribution to knowledge, which aligns with the journal’s “impact, novelty not assessed” policy.
2. While the data from the literature are presented, their robustness is somewhat variable due to the nature of the included studies. The authors acknowledge several limitations of those underlying studies. For one, sample sizes in the primary studies were generally very small (ranging roughly 10–40 participants each). Such small-n studies diminish statistical power and raise concerns about how representative or reliable the findings are. Moreover, not all included experiments were rigorously controlled randomized trials – the inclusion criteria allowed single-group (pre-post) trials as well. Some studies lacked a separate control group or used only pre- vs. post-training comparisons, which introduces potential confounding factors (e.g., improvements could be partly due to general practice or placebo effect rather than the core training specifically). The review does include controlled trials (some with experimental vs. control groups), but the mix of study designs means the overall evidence base isn’t uniformly strong. This is a weakness in the underlying data that the authors needed to navigate.
3. The included studies collectively show positive effects of core training, but there is considerable heterogeneity in what outcomes were measured and how. Different papers assessed various performance metrics – one counted kick frequency, another measured punching force, others looked at core strength tests or balance, etc. This lack of standardized outcome measures makes it difficult to quantitatively synthesize results or directly compare effect sizes across studies. Additionally, some performance tests might be subjective or have measurement error (the authors mention, for example, that tests like counting strikes in 30 seconds could suffer from accuracy issues without standardized instruments). These inconsistencies and potential biases in the underlying data could affect the soundness of the conclusions. The manuscript would benefit from a more formal evaluation of these aspects (see points on risk-of-bias below)
4. The research question is clearly defined and meaningful. It asks, in essence, “What are the effects of core strength training on technical skill performance in combat sport athletes?” This question is explicitly stated as the purpose of the review in the introduction (the authors write that the purpose is to explore the importance/effects of core strength training in combat sports). It’s a highly relevant question for sports science – coaches and athletes frequently incorporate core training, but understanding how much it enhances sport-specific skills (like punch force or kick speed) addresses a real knowledge gap.
5. The manuscript identifies an existing gap in the literature and positions the research question to fill it. Specifically, it notes that although core strength is known to be important, “numerous studies…have focused on general athletic performance rather than the nuances of combat sports”. This implies that no comprehensive review has yet synthesized the evidence specifically for combat sports techniques, which is exactly what this study aims to do. The rationale could be made even more explicit; for instance, the authors do not cite any prior systematic review on core training, suggesting there truly wasn’t one focused on this niche. They might strengthen the introduction by clearly stating, “To date, no systematic review has examined core training effects in combat sports, despite plenty of isolated studies.”
1. The underdeveloped component is the absence of a formal quality assessment of the included studies. The methods do not describe any risk-of-bias evaluation or quality scoring, and no results of such an appraisal are reported. Systematic reviews should typically assess study quality (e.g., using a tool like PEDro or Cochrane risk-of-bias) , but here the reader is given no indication of how robust or reliable each study’s findings are. This omission compromises the manuscript’s completeness – we cannot tell if, for example, studies with small sample sizes or other limitations were weighted appropriately in the analysis. The Discussion acknowledges some limitations of individual studies (such as small sample sizes and inconsistent intervention durations), but this qualitative commentary is not a substitute for a systematic bias assessment. Without a risk-of-bias analysis, the review’s synthesis of findings may be overly optimistic, since it doesn’t account for weaker evidence possibly skewing the conclusions.
Provide quality assessment
2. The results presentation focuses almost exclusively on positive improvements in technical skills, with little mention of outcomes that showed no effect. Every included study is summarized as finding significant gains (e.g., increased kick counts, punch power, etc.), and the conclusion asserts uniformly positive effects of core training across all combat sports. However, some outcomes within those studies did not improve and are downplayed or omitted in the narrative. For example, Zhang et al. (2023) measured several performance indices in boxers; while punch frequency and power improved, aerobic endurance (a 400m run test) showed no significant difference after the core training intervention. The manuscript’s text does not mention this null finding – it only highlights the gains in striking performance. Such selective reporting can mislead readers by emphasizing beneficial results while ignoring measures where core training had little impact. All results relevant to the hypothesis (positive, null, or negative) should be included and discussed to present a balanced, self-contained account. The absence of any discussion on non-improved outcomes is a shortcoming in completeness and objectivity.
Provide an explanation in the discussion section.
3. Finally, the “Practical application” section is a good idea in principle, distilling advice like incorporating core training “at least twice a week for 6 weeks” based on the eight studies’ protocols. However, this recommendation appears somewhat ad hoc. It isn’t clearly derived from a comparative analysis (indeed, intervention durations ranged from 6 weeks to 24 weeks across studies). By cherry-picking the lowest common denominator (twice weekly, 6-week minimum), the practical advice might be conservative, but it doesn’t acknowledge the possibility that longer or more frequent training could yield greater benefits. In short, the discussion and conclusion provide general takeaways but stop short of a comprehensive integration of all relevant results and nuances.
Strengthening this section to connect the dots – between the data, the limitations, and the actionable guidance – would make the manuscript a more coherent and complete piece.
4. The authors succinctly summarize that core strength training has significant positive effects on multiple combat sports, enhancing metrics like kick frequency, striking power, and impact speed They enumerate sport-specific findings (e.g. improved wheel kick performance in karate, more kicks in taekwondo, greater punch power in boxing, etc.), which makes it very clear how the results answer the question posed. This linkage ensures that the conclusions aren’t straying beyond what was investigated – they circle back to “technical skill performance in combat sports” as initially intended. The wording in the conclusion section matches the evidence presented: for instance, it highlights improvements in power and speed performance, which were indeed the types of outcomes measured across the included studies. Overall, the conclusions do a good job of encapsulating the review’s findings in plain terms, making them understandable and relevant to coaches or practitioners (the target audience mentioned in the intro).
5. Generally, the authors limit their conclusions to what the results support, but there are a few instances to note where the phrasing could be more cautious. The conclusion asserts that core training improved athletes’ “aggression, speed, and endurance”. While speed and some measure of endurance (e.g., sustaining strikes over 1 minute) were directly observed outcomes in the studies, aggression is a more interpretive term, presumably referring to the increased number of offensive actions like kicks or punches. Since “aggression” wasn’t a quantified variable, this could be rephrased to something like “offensive output” for clarity. Additionally, the concluding paragraphs mention that core training helps reduce fatigue and the risk of injury for athletes. This is plausible (and supported generally by exercise science literature), but it’s not something any of the reviewed studies measured (none of the eight studies tracked injury rates or long-term fatigue). Thus, including injury risk reduction as a conclusion extends beyond the immediate evidence provided by the systematic review. It would be more appropriate as a general discussion point or implication rather than a firm conclusion. This is a minor overreach in an otherwise evidence-grounded conclusion section. Lastly, given the limitations of the underlying studies (small samples, etc.), the authors might temper phrases like “has demonstrated significant positive effects in several combat sports” with a reminder of the preliminary nature of evidence.
Strengths:
• The manuscript follows PRISMA guidelines and includes proper structural components.
• The introduction provides a comprehensive background and rationale for the study.
• Figures and tables (e.g., PRISMA flow diagram and Table 1) are relevant and informative.
Areas for Improvement:
• While generally written in academic English, the manuscript contains several grammatical and syntactic issues that may hinder clarity (e.g., lines 23, 51, 126, 358).
• Repetitive use of terms such as "static and dynamic core training" could be reduced or rephrased for better readability.
• It is strongly advised to seek professional language editing or proofreading by a native English speaker.
Strengths:
• The systematic review was pre-registered (INPLASY2023120102), enhancing transparency.
• The search strategy used multiple databases and applied the PICOS framework.
• The study selection and data extraction procedures are clearly described and involve multiple reviewers.
Limitations and Recommendations:
1. Only 8 studies were included out of an initial pool of 826, which limits the comprehensiveness and generalizability of the findings.
2. There is significant heterogeneity across included studies in terms of intervention duration, frequency, and outcome measures.
3. Most included studies were pre-post designs; very few employed randomized controlled methodologies, limiting the strength of the conclusions.
Strengths:
• The review provides structured and sport-specific summaries of findings (e.g., karate, boxing, Muay Thai).
• The conclusions are generally aligned with the reported results.
Critical Gaps:
1. No formal risk of bias assessment was conducted. Inclusion of tools such as the Cochrane RoB tool or ROBINS-I would strengthen the manuscript.
2. No meta-analysis was conducted, nor was a justification provided for its omission. If not feasible, a clearer rationale should be given.
3. Measurement tools varied widely and in some cases lacked standardization. For example, subjective metrics such as 30s strike counts may not offer robust reliability.
General Comments
Strengths:
• The topic is timely and practical, with clear applications for strength & conditioning in combat sports.
• Inclusion of specific performance outcomes (e.g., number of kicks, punching force) makes the paper relevant to coaches and applied researchers.
• The section on sport-specific applications of core training is particularly insightful.
Weaknesses and Suggestions:
1. Bias assessment must be added for methodological rigor.
2. Table 1 is overly dense and could be reformatted for clarity (e.g., use of abbreviations, column grouping).
3. A deeper comparative discussion between static vs dynamic core training effects is warranted, especially given its highlighted relevance in the Muay Thai studies.
4. The Practical Applications section should be expanded with more concrete recommendations (e.g., suggested exercises, training intensity, weekly frequency).
The problem with the study is that the title and introduction refer to all combat sports, while the results and discussion refer only to striking combat sports (sports involving punches and kicks). None of the articles included in the study refer to grappling sports (wrestling, judo) or mixed martial arts (MMA).
The results of the study can be confusing because this issue is very different for striking and grappling sports. The article was intended to be designed for striking sports only, which is evident from the conclusion, which does not mention a single combat sport with grappling elements.
The methodology of this type of research is fine and provides all that is necessary. The problem is that the studies selected are not of high quality (which is stated in the limitations of the study). Very few studies were found in WOS Scopus or PubMed. We do not know if any of these studies were included in the review. It would be interesting to know in which databases the studies are indexed
The article only refers to a part of combat sports (without grappling sports), this should be changed in the entire article.
The validity is reduced by the quality of the studies included in the review, which is mentioned in the study limitations.
Grappling sports are full of lifting, carrying, throwing, and holding. These sports intensively develop core strength, and elite fighters differ from non-elite fighters in core strength. This is not the case in other combat sports. Therefore, this article should focus on striking/kicking sports.
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