1 Introduction

The knee joint is one of the most complex and most commonly injured joints in the human body. It plays a crucial role in daily activities such as sports, walking, and running. Knee joint injuries are prevalent health issues, especially among athletes and the elderly, with conditions such as anterior cruciate ligament (ACL) injuries, meniscus injuries, and degenerative changes in knee joint cartilage being particularly common. Studies have shown that muscle weakness is one of the key factors contributing to knee joint injuries.^1,2 During the rehabilitation process following injuries, particularly after surgeries such as ACL reconstruction and knee joint replacement, muscle strength assessment and recovery are critical.³

Isokinetic strength testing is an advanced method for assessing muscle strength by measuring the force output of muscles throughout the entire range of motion of the joint at a fixed velocity.⁴ This test not only quantifies muscle strength but also measures endurance, explosive power, and performance at various speeds, making it widely used in sports medicine and rehabilitation.^5–7 As a valid and reliable test, isokinetic testing has become one of the gold standards for evaluating knee joint function in clinical practice and scientific research. It helps rehabilitation professionals accurately quantify the recovery of muscle strength, assess whether the knee joint has reached functional recovery standards, and assist individuals in safely returning to sports or daily activities.⁸ Additionally, it can predict the future risk of knee joint injuries and help prevent potential issues caused by muscle strength imbalances.

Although there has been a substantial amount of research on knee joint isokinetic muscle strength, the diversity of these studies may cause some confusion among researchers. Currently, the research mainly focuses on the application of isokinetic muscle strength in sports injuries, the study of muscle strength imbalances, and how isokinetic strength can be used to prevent knee joint sports injuries. Therefore, scientifically summarizing the research literature in this field is of great significance. Bibliometrics is a retrospective statistical method used to find correlations in data and predict future developments.⁹ CiteSpace and VOSviewer are currently the most comprehensive and widely used visualization tools for tracking and analyzing the development trends and cutting-edge hotspots in a particular field.¹⁰ Using bibliometric methods, this study conducts a statistical analysis of knee joint isokinetic muscle strength-related literature published in the Web of Science over the past 30 years. The aim is to reveal the research output, cutting-edge developments, research hotspots, research institutions, and development trends in this field from the perspective of scientific literature production. It is hoped that this study will provide a reference for researchers in the field and offer some clues for future research directions.

2 Materials and methods

2.1

2.1 Data sources and search strategies

This study selected the Web of Science Core Collection (WOSCC) as the data source. As a high-quality literature resource database, Web of Science (WOS) is widely accepted by researchers and is currently the most suitable database for bibliometric analysis. To ensure the accuracy and quality of the search data, the index selected was the WOSCC, and the search strategy was as follows: ((TI=(isokinetic))) AND TS=(knee). The retrieved literature was then screened, and the specific process is shown in Fig. 1. A total of 1013 valid publications were obtained. The data acquired from WOSCC included titles, keywords, publication dates, authors, institutions, countries/regions, journals, and total citations. To avoid biases due to frequent database updates, all literature searches and data downloads were completed within a single day, on October 18, 2024. The WOS database is the sole source of information for this study, and since no human participants were involved, ethical consent was not required.

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Fig. 1 Flow diagram of research selection and screening.

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3 Results

3.1

3.1 Publication output and time trend

As described in Section 2.1, a total of 1162 papers were initially retrieved using the defined search strategy. After excluding 109 papers that were unrelated to articles or reviews, 1053 papers remained. Subsequently, 40 non-English papers were further excluded. After a thorough review of the full texts, a total of 1013 papers were finally included in this bibliometric analysis. The selection process is shown in Fig. 1.

The 1013 papers included in this study were authored by 3456 researchers from 1305 institutions across 61 countries and were published in 221 journals. These papers cited 16,429 references from 1360 different journals. From 1994 to 2024, the number of research papers on knee joint isokinetic muscle strength showed an overall upward trend. The year 2020 marked a peak in the number of publications, as shown in Fig. 2.

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Fig. 2 Annual publications and citations on knee isokinetic strength from 1994 to 2024.

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3.3

3.3 Analysis of publishing journals

The top ten journals in terms of knee joint isokinetic muscle strength publications have collectively published 387 papers, accounting for 38.2 % of the total literature (Table 2). Using the 2023 Journal Citation Reports (JCR), we obtained the latest impact factor (IF) of these journals as a fundamental criterion for evaluating their academic influence.¹⁴ The top five journals in terms of publication volume include Isokinetics and Exercise Science (171 articles, 16.9 %), Journal of Strength and Conditioning Research (45 articles, 4.4 %), International Journal of Sports Medicine (27 articles, 2.6 %), Journal of Sports Medicine and Physical Fitness (23 articles, 2.2 %), and Archives of Physical Medicine and Rehabilitation (21 articles, 2.0 %).

Table 2 Top ten productive journals related to knee isokinetic strength.

Rank	Journal	Number	Totalcitations	Average per year	IF in 2023
1	Isokinetics and Exercise Science	171	1824	10	0.60
2	Journal of Strength and Conditioning Research	45	1128	25	2.50
3	International Journal of Sports Medicine	27	1216	45	2.00
4	Journal of Sports Medicine and Physical Fitness	23	683	29	1.20
5	Archives of Physical Medicine and Rehabilitation	21	1382	65	3.60
6	European Journal of Applied Physiology	21	1008	48	2.80
7	Journal of Electromyography and Kinesiology	21	604	28	2.00
8	Journal of Sport Rehabilitation	21	253	12	1.30
9	Journal of Orthopaedic & Sports Physical Therapy	20	1331	66	6.00
10	Knee Surgery Sports Traumatology Arthroscopy	17	725	42	3.30

Additionally, as shown in Fig. 3, VOSviewer was used for a co-citation analysis of journals, where the node size represents the number of citations. The results reveal that Isokinetics and Exercise Science, Archives of Physical Medicine and Rehabilitation, and Journal of Orthopaedic & Sports Physical Therapy are highly cited journals, positioned at the center of the co-cited journals network. Among them, Isokinetics and Exercise Science published the highest number of papers among the listed journals, with a total of 171 articles. This indicates that the journal holds high authority and focus in the field of knee joint isokinetic muscle strength research. However, its IF is only 0.60, suggesting that despite the high publication volume, the overall academic influence of its papers is relatively low. Although Journal of Orthopaedic & Sports Physical Therapy has a lower publication count, it has the highest average annual citation rate and IF, indicating its strong recognition in the fields of sports rehabilitation and physical therapy.

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Fig. 3 Citation analysis of published journals.

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3.4

3.4 Analysis of communications from different countries

In terms of the number of published papers, the USA ranked first with 211 papers (20.8 %), followed by the UK (90 papers, 8.8 %), Brazil (89 papers, 8.7 %), Turkey (75 papers, 7.4 %), France (74 papers, 7.3 %), and Greece (53 papers, 5.2 %). Table 3 displays the six countries with the highest total number of publications. The top five countries with the highest total citation counts are the USA (6,496), the UK (2,994), Brazil (1,582), Turkey (1,256), and France (1,962). The USA is the country with the most publications and the highest citation frequency.

Table 3 Top six countries and citation frequency of literature.

Rank	Countries	Studiescounts	Totalcitations	Average per study
1	USA	211	6496	30
2	England	90	2994	33
3	Brazil	89	1582	17
4	Turkey	75	1256	16
5	France	74	1962	26
6	Greece	53	1374	25

We analyzed the level of collaboration among countries in this field and used R software to create a network map of inter-country collaborations. As shown in Fig. 4, the color intensity indicates the publication volume, and the connections between nodes represent direct collaborative relationships between countries. The analysis reveals that the USA has closer collaboration with other countries.

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Fig. 4 Countries collaboration analysis. The lines represent connections between countries. The color intensity of each country on the map corresponds to the number of publications, with darker colors indicating more publications. The number of connecting lines reflects the level of collaboration between countries.

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3.5

3.5 Analysis of article publishing organizations

Globally, Aristotle University of Thessaloniki (32 papers, 3.15 %) is the university with the highest number of publications in this field over the past 30 years, far surpassing other institutions. Its articles have been cited 677 times, indicating its leading position in knee joint isokinetic muscle strength research and its role as a significant academic center in the field. Among the top ten institutions by publication volume, three from the United States are included, highlighting the country's important role in this area of research. Additionally, institutions from Greece, Brazil, Israel, France, and England are also on the list, demonstrating the strong international and multi-center nature of knee joint isokinetic muscle strength research (Table 4). Next, we used CiteSpace for a visual analysis of institutional collaborations, revealing the cooperation between institutions (Fig. 5).

Table 4 Top ten institutions published studies related to knee isokinetic strength.

Rank	Institutions	Country	Number	Total Citations	Average per year	Percentage (N/1013)
1	Aristotle University of Thessaloniki	Greece	32	677	21	3.15
2	Universidade de Brasília	Brazil	18	277	15	1.77
3	Tel Aviv University	Israel	17	291	17	1.67
4	California State University	USA	16	441	27	1.57
5	Nantes Université	France	16	285	17	1.57
6	State University System of Florida	USA	15	358	23	1.48
7	Universidade de São Paulo	Brazil	15	248	16	1.48
8	University of Nebraska Lincoln	USA	15	452	30	1.48
9	University of Nebraska System	USA	15	452	30	1.48
10	Manchester Metropolitan University	England	14	648	46	1.38

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Fig. 5 A VOSviewer network visualization of keywords in publica tions of knee isokinetic strength. Nodes represent institutions, and lines indicate the connections between them. The size of the node is proportional to the number of publications, while the thickness of the connecting line reflects the degree of collaboration. The outermost purple circle indicates higher centrality. From 1994 to 2024, the color transitions from light yellow-blue to dark blue.

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3.6

3.6 Analysis of keywords of the publications

From the titles and abstracts of the 1013 articles included, 89 keywords with a frequency greater than or equal to 20 were extracted, and a co-occurrence analysis of these keywords was conducted using VOSviewer. As shown in Fig. 6A, the 89 keywords were divided into four clusters: Cluster 1 (related to basic research on knee joint function and fatigue characteristics, red), Cluster 2 (related to rehabilitation treatment of sports injuries, green), Cluster 3 (related to research on sports performance, quadriceps strength, and injuries, blue), and Cluster 4 (related to the reliability and validity of isokinetic testing tools in experimental research, yellow). The size of the nodes represents the frequency of keyword occurrence. The nodes are colored according to the time of keyword appearance (Fig. 6B). High-frequency keywords predominantly appeared between 2008 and 2016. Dark blue indicates keywords that appeared earlier, while yellow represents more recent keywords.

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Fig. 6 A VOSviewer network visualization of keywords in publica tions of knee isokinetic strength. (A)Mapping of the keywords in the area. The words were divided into five clusters in accordance with different colors generated by default: basic research on knee joint function and fatigue characteristics (red), rehabilitation treatment research (green), knee joint rehabilitation research (blue), and research on the reliability and validity of isokinetic testing (yellow). The circle with a large size represents the keywords that appeared at a high frequency. (B) Distribution of keywords was presented according to the appearance for the average time. Keyword bursts mainly focus on 2008–2016. The blue color represents an early appearance and the yellow color represents a recent appearance. The smaller the distance between two keywords, the larger the number of co-occurrences of the keywords.

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To further understand the research hotspots in knee joint isokinetic muscle strength, we used CiteSpace's burst analysis feature to analyze articles published in this field from 1994 to 2024, identifying 24 keywords. Burst keywords are those that appear frequently within a specific time period. They not only highlight the evolution of research hotspots over time but also suggest recent trends and provide insights into future research directions. As shown in Fig. 7, “anterior cruciate ligament” (burst strength 9.44), “men” (7.88), and “skeletal muscle” (5.72) were popular topics in the field from 1994 to 2004. In the following decade, research hotspots shifted towards “sports medicine” (burst strength 4.5), “test-retest reliability” (6.89), and “dynamometer” (4.81), indicating that the rise of sports medicine led to a shift in knee joint isokinetic muscle strength research from basic to clinical applications, particularly in rehabilitation and injury prevention. Researchers also became more focused on the reliability of isokinetic dynamometers and the standardization of testing methods. In recent years, “anterior cruciate ligament reconstruction” (burst strength 4.67), “quadriceps strength” (burst strength 9.28), and “sport” (burst strength 9.79) have gradually become prominent topics (Fig. 7).

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Fig. 7 The top 24 keywords in knee isokinetic strength field. The blue line represents the timeline, and the red portion represents the time period in which the keyword outbreak occurred, including the start year, end year, and outbreak duration.

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3.7

3.7 Analysis of the co-citations

We ranked the 1013 retrieved articles based on citation frequency and listed the top 10 most-cited articles (Table 5). The most-cited paper is Isokinetic Strength and Anaerobic Power of Elite, Subelite, and Amateur French Soccer Players, authored by Nicola A. Maffiuletti in 2001 and published in the International Journal of Sports Medicine.¹⁵ This paper has been cited 366 times in total, with an average annual citation frequency of 15.3 times. Additionally, Maximal Isokinetic and Isometric Muscle Strength of Major Muscle Groups Related to Age, Body Mass, Height, and Sex in 178 Healthy Subjects, published in 2012 by Thomas Harbo John Brincks Henning Andersen, and others in the European Journal of Applied Physiology, although having a total of 252 citations, boasts an average annual citation frequency of 19.4, ranking it among the top ten most-cited papers. Among the top ten, International Journal of Sports Medicine, Journal of Orthopaedic & Sports Physical Therapy, and Journal of Applied Physiology each published two highly cited articles, while the others were published in different journals. Next, we performed a co-citation analysis using VOSviewer. The results revealed a co-citation pattern for 63 papers that have been cited more than 30 times. The paper Isokinetic Evaluation of Muscular Performance: Implications for Muscle Testing and Rehabilitation is at the center of the co-citation network (Fig. 8).

Table 5 Top ten high-cited papers related to knee isokinetic strength.

Rank	Title	Corresponding authors	Journal	Publication Year	Total Citations	Average per year
1	Isokinetic strength and anaerobic power of elite, subelite and amateur French soccer players	Nicola A. Maffiuletti	International Journal of Sports Medicine	2001	366	15.3
2	A new concept for isokinetic hamstring: Quadriceps muscle strength ratio	Per Aagaard	American Journal of Sports Medicine	1998	357	13.2
3	The relationship between subjective knee scores, isokinetic testing, and functional testing in the ACL-reconstructed knee	Kevin E. Wilk, PT	Journal of Orthopaedic & Sports Physical Therapy	1994	312	10.1
4	Isokinetic evaluation of muscular performance: implications for muscle testing and rehabilitation	P. Kannus	International Journal of Sports Medicine	1994	273	8.8
5	Maximal isokinetic and isometric muscle strength of major muscle groups related to age, body mass, height, and sex in 178 healthy subjects	Thomas Harbo • John Brincks • Henning Andersen	European Journal of Applied Physiology	2012	252	19.4
6	β-alanine supplementation augments muscle carnosine content and attenuates fatigue during repeated isokinetic contraction bouts in trained sprinters	Wim Derave	Journal of Applied Physiology	2007	235	13.1
7	The relationship between isokinetic quadriceps strength test and hop tests for distance and one-legged vertical jump test following anterior cruciate ligament reconstruction	Renate Petschnig	Journal of Orthopaedic & Sports Physical Therapy	1998	234	8.7
8	Isokinetic hamstring/quadriceps strength ratio: influence from joint angular velocity, gravity correction and contraction mode	Per Aagaard	Acta Anaesthesiologica Scandinavica	1995	228	7.6
9	Test-retest reliability of isokinetic knee extension and flexion	Gisela Sole	Archives of Physical Medicine and Rehabilitation	2007	197	10.9
10	Antagonist muscle coactivation during isokinetic knee extension	Per Aagaard	Scandinavian Journal of Medicine & Science in Sports	2000	192	7.7

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Fig. 8 Co-citation map related to knee isokinetic strength.

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4 Discussion

Based on the WOSCC database, we retrieved knee joint isokinetic muscle strength-related literature published up to June 2024 and conducted bibliometric and visual analysis to comprehensively understand the current state of research in this field, infer research hotspots, track the frontier of the discipline, and provide references for future research directions. By analyzing the output and citation patterns of scientific literature, we can visually display the academic level and influence of countries, institutions, and scholars in this field, revealing their roles in the development of knee joint isokinetic muscle strength research.

The number of published papers in the field of knee joint isokinetic muscle strength has been increasing year by year. In recent years, the number of publications in this field has steadily grown, peaking in 2020, indicating that this research area has become a global research hotspot. The notable increase in the number of published papers in 2020 may be attributed to multiple factors, including the combined effects of global disruptions caused by the COVID-19 pandemic and field-specific influences.^16,17 On one hand, the pandemic significantly altered the landscape of academic research. Due to challenges in obtaining participant informed consent and widespread restrictions on athletic events and clinical activities, many researchers likely shifted their focus toward literature-based studies while also gaining additional time for data analysis and manuscript preparation. On the other hand, a more specific and enduring driver during this period was the rapid interdisciplinary integration of sports medicine, rehabilitation science, and biomechanics. Over the past decade, ACL injuries,^18–20 neuromuscular asymmetry,^1,21 and personalized rehabilitation protocols have remained key areas of research focus.^22,23 These fields all require precise, quantitative assessments of muscular performance demands, and isokinetic knee muscle strength testing—with its reliability, objectivity, and ability to dynamically evaluate muscle function under controlled conditions—has emerged as a critical assessment tool.^7,8,24 This interdisciplinary convergence has not only expanded the applications of isokinetic analysis techniques but also substantially increased research output by generating novel research questions and addressing emerging clinical needs. Although there was a slight decline after the peak, we speculate that knee joint isokinetic muscle strength will continue to be a key research focus in the coming years. From the distribution of authors and citations, it is evident that a core group of authors has formed in this field.

Based on journal citation frequency and IF, Isokinetics and Exercise Science (IF = 0.60), Archives of Physical Medicine and Rehabilitation (IF = 3.60), and Journal of Orthopaedic & Sports Physical Therapy (IF = 6.00) are other major journals publishing related articles. Researchers in this field are advised to focus on the relevant literature published in these journals, stay updated on the latest trends and advancements in international knee joint isokinetic muscle strength research, and expand the breadth and depth of their own research to enhance international recognition.

Globally, the USA leads with 211 publications, demonstrating its largest research scale and greatest international academic contribution in this field. The total citation count for the USA is 6,496, with an average of 30 citations per paper, showing that not only is the USA leading in publication quantity, but also in research quality. The UK follows closely behind, with 90 publications (8.8 % of total papers), but its average citation count per paper is 33, the highest among all countries. This indicates that UK research focuses on quality, and its results have a significant international impact. The USA also has the closest academic exchanges and collaborations with other countries.

In the context of global integration, we expect more multinational collaborations in future research. Additionally, in terms of the number of publications and citation counts from research institutions, four institutions from the USA rank among the top ten, including California State University, State University System of Florida, University of Nebraska Lincoln, and University of Nebraska System. These institutions' strong performance reflects the USA's leading position in knee joint isokinetic muscle strength research and its considerable international influence. The top-ranked institution globally is Aristotle University of Thessaloniki from Greece, with 32 publications, 677 total citations, and an average of 21 citations per paper. This represents 3.15 % of the total publications, indicating its significant contribution to knee joint isokinetic muscle strength research, widely recognized by international scholars. Notably, although Manchester Metropolitan University in the UK published the fewest papers among the top ten institutions, it had 648 citations in total, second only to Aristotle University, with an average of 46 citations per paper, the highest among the top ten. This reflects the high academic impact of its research results. The advanced equipment, professional researchers, ample funding, and widespread academic exchanges give the USA a leading position in this field. However, to maintain this leadership, the USA will need continued participation from more outstanding scholars and institutions in future research.

High citation frequency of a paper signifies its substantial academic influence in a particular field. The top ten most cited articles related to knee joint isokinetic muscle strength are listed in Table 5. The most frequently cited paper on this topic is “Isokinetic Strength and Anaerobic Power of Elite, Subelite and Amateur French Soccer Players”, published in 2001 in the International Journal of Sports Medicine (IF = 2.0). This study offers a detailed analysis of the physical differences among elite, subelite, and amateur soccer players, emphasizing the role of knee flexor strength, the hamstring/quadriceps ratio, and anaerobic power in athletic performance. The study highlights that enhancing knee flexor strength and the hamstring/quadriceps ratio can improve an athlete's explosive power and performance. Furthermore, elite athletes typically maintain a high competitive level through more balanced strength development, suggesting that athletes at other levels can narrow the gap with elite players through targeted training.¹⁵ The article with the highest annual citation frequency is “Maximal Isokinetic and Isometric Muscle Strength of Major Muscle Groups Related to Age, Body Mass, Height, and Sex in 178 Healthy Subjects”, published in European Journal of Applied Physiology. This study measures isokinetic and isometric muscle strength in healthy individuals, analyzing the impact of factors such as age, body weight, height, and gender on muscle strength. The results show that age and body weight significantly affect muscle strength, with different patterns of influence observed between men and women. This paper provides muscle strength standards based on physiological characteristics for healthy individuals, with practical implications in sports, rehabilitation, and elderly health management. Understanding muscle strength performance across different groups can help guide personalized training and rehabilitation programs.²⁵ In addition, two highly cited articles published in the Journal of Orthopaedic & Sports Physical Therapy examine the assessment of knee joint function and muscle strength recovery following ACL reconstruction. These papers, “The Relationship Between Subjective Knee Scores, Isokinetic Testing, and Functional Testing in the ACL-Reconstructed Knee” and “The Relationship Between Isokinetic Quadriceps Strength Test and Hop Tests for Distance and One-Legged Vertical Jump Test Following Anterior Cruciate Ligament Reconstruction”, explore how isokinetic testing combined with functional tests can help clinicians more accurately assess the overall recovery of patients post-ACL reconstruction. These studies underscore the importance of comprehensive functional and isokinetic assessments in evaluating recovery progress following knee surgery.^26,27

The most recent burst terms in the field of knee joint isokinetic muscle strength research include “anterior cruciate ligament reconstruction”, “asymmetry”, “risk” and “quadriceps strength”. These terms reflect the evolving focus on the application of isokinetic muscle testing in sports injuries and rehabilitation. Since 2018, “anterior cruciate ligament reconstruction” has emerged as a burst term and has continued through to 2024, indicating that the application of isokinetic muscle testing in ACL reconstruction rehabilitation has become a core research direction in recent years. Studies have increasingly focused on muscle strength recovery, knee joint function assessment, and long-term athletic performance after ACL reconstruction.¹⁸ Additionally, the terms “risk” (2024) and “asymmetry” (2021–2024) have recently emerged as important burst terms. This reflects a new trend in knee joint isokinetic muscle strength research: the functional recovery of the knee joint is no longer solely dependent on the restoration of unilateral muscle strength but is shifting towards a focus on symmetry between the two sides of the knee. Asymmetry is now recognized as a key factor influencing athletic performance and injury recovery.^1,28 This trend aligns with the growing importance of achieving balance in muscle strength on both sides of the body, particularly for athletes during recovery. Finally, “quadriceps strength” (2020–2024) has become another burst term, emphasizing the significant role of quadriceps strength in knee stability and rehabilitation. Research has been increasingly focused on how to promote quadriceps strength recovery after ACL reconstruction and enhance knee stability, aiming to improve athletic performance and reduce the risk of re-injury.^29,30 The emergence of these burst terms reflects the growing academic interest in the application of isokinetic muscle testing in both injury recovery and performance enhancement. It also provides clear guidance for future research directions, particularly with respect to symmetry, risk management, and quadriceps strength in knee rehabilitation. It is important to note that burst keyword detection is sensitive to dataset selection. The choice of database and time window can influence the identification of emerging trends. While the use of the Web of Science Core Collection provides a reliable dataset for this study, future research may benefit from integrating qualitative expert insights to better contextualize the identified keywords and assess their significance in a broader academic context.

5 Limitations of the study

This study systematically retrieved data from the WOS database and comprehensively and objectively analyzed the research progress in the field of isokinetic muscle strength in the knee joint over the past 30 years. It acknowledged the contributions of authors, countries, research institutions, and journals, and from a bibliometric perspective, it analyzed and predicted future research hotspots, providing reference suggestions for future research directions in this field. However, some limitations are unavoidable. Firstly, due to the limitations of bibliometric software, this study only retrieved data from the WOSSC database and did not include relevant literature from other databases. Secondly, only English-language articles were included, which means that potentially valuable non-English literature may have been excluded. Thirdly, the literature type included in the study was limited to dissertations and reviews, thus excluding conference papers and books that may have academic impact. Finally, bibliometrics is a quantitative analysis method and cannot fully and systematically assess the quality of the published literature.

6 Conclusion

Research on knee isokinetic strength has advanced rapidly. This study provides a condensed map of global research developments on knee isokinetic strength, highlighting evolving priorities in rehabilitation and performance science. While publication volume and collaborative networks have expanded, unresolved issues persist—particularly the lack of standardized protocols, inconsistent interpretation of strength asymmetry, and limited population-specific data. Future research should emphasize methodological unification, integration with neuromuscular and biomechanical modeling, and clinically validated thresholds to guide personalized rehabilitation and return-to-sport decisions. Addressing these gaps will enhance translational impact and improve evidence-based practice in sports medicine and orthopaedic rehabilitation.

Informed consent (patient/guardian), mandatory only for case reports/clinical images

N/A.

Ethical statement

1)This material is the authors' own original work, which has not been previously published elsewhere.2)The paper is not currently being considered for publication elsewhere.3)The paper reflects the authors' own research and analysis in a truthful and complete manner.4)The paper properly credits the meaningful contributions of co-authors and co-researchers.5)The results are appropriately placed in the context of prior and existing research.6)All sources used are properly disclosed (correct citation). Literally copying of text must be indicated as such by using quotation marks and giving proper reference.7)All authors have been personally and actively involved in substantial work leading to the paper, and will take public responsibility for its content.

CRediT authorship contribution statement

Jiangfeng Lv: Investigation, Writing – original draft, Visualization. Yaoxin Ao: Investigation, Methodology, Writing – review & editing. Wenli Luo: Conceptualization, Writing – review & editing. Fangjun Xiao: Methodology, Formal analysis, Investigation, Writing – review & editing. Yifei Liufu: Investigation, Formal analysis, Writing – review & editing. Junxing Yang: Conceptualization, Writing – review & editing, Supervision.

Funding/sponsorship

This research did not receive any specific grant from funding agencies in the public, commercial or not-for-profit sectors.