Open research questions in Lower Extremity Biomechanics and Pathologies

What the literature leaves open

• The comparative analyses showed that PFMT video quality varied across video topics, publisher categories, video duration groups, and platforms. These differences suggest that a single communication feature does not determine the quality of PFMT videos but is related to the combined role of content orientation, creator background, presentation length, and platform engagement patterns. In terms of video topics, videos categorized as “Pelvic Floor Muscle Training and Exercise Guidance” showed higher shares and favorites and achieved higher PEMAT-A/V understandability and actionability scores. This suggests that practice-oriented, structured content may be more easily ARTICLE IN PRESS ARTICLE IN PRESS ACCEPTED MANUSCRIPT understood and applied by users. This finding is consistent with evidence that structured PFMT interventions, including those combined with biofeedback or bladder training, may improve adherence to training and intervention effectiveness [10,32,34]. Group-based education has also been shown to support long-term awareness of pelvic floor health and self-management skills [33], which further suggests the educational value of structured, practice-oriented guidance. However, exercise-guidance videos should not be evaluated solely on their actionability; they also need sufficient explanation of the evidence sources, contraindications, and risk warnings. From the perspective of publisher categories, videos uploaded by healthcare professionals and science communicators tended to have higher information quality. However, the differences were not uniform across all quality dimensions. This finding is consistent with previous studies showing that clinicians and professional institutions are important sources of information on pelvic floor health for women [31]. At the same time, health- related short-video content often comes from diverse sources and varies in reliability and quality [35]. One possible explanation is that different assessment tools emphasize different aspects of video quality. PEMAT-A/V mainly evaluates the understandability and actionability of patient education materials[28]. Therefore, PEMAT-A/V understandability is more closely related to whether information is presented clearly and in an audience- friendly manner than to the uploader’s professional identity alone. In the short-video context, healthcare professionals, fitness or exercise influencers, ARTICLE IN PRESS ARTICLE IN PRESS ACCEPTED MANUSCRIPT individual users, and organizations may all use similar presentation formats, such as demonstrations, subtitles, simplified explanations, and step-by-step instructions. This similarity in audiovisual presentation may reduce between- group differences in understandability. By contrast, science communicators may have stronger advantages in translating professional knowledge into accessible language, which may explain their higher understandability scores.

  Assessment of pelvic floor muscle training video information quality and associated factors on Douyin and Bilibili: a cross-sectional study · 2026 · DOI

• Future research should investigate the long-term effectiveness of proprioceptive training programs and their impact on return-to-sport outcomes. Incorporating biomechanical assessments, including three-dimensional motion analysis and electromyographic evaluation, would help clarify the movement adaptations associated with these interventions. Mul- ticenter trials involving diverse athletic populations are needed to strengthen the generalizability of the findings, while studies exploring individualized rehabilitation approaches based on baseline neuromuscular deficits may further improve treatment effectiveness. Additional investigations should also examine optimal training parameters, including the fre- quency, intensity, and progression of proprioceptive exercises, to inform evidence-based rehabilitation protocols for PFPS. PLOS One | https://doi.org/10.1371/journal.pone.0353107 July 24, 2026 20 / 24 Furthermore, future studies should evaluate the psychometric properties, weighting strategies, external validity, and clini- cal interpretability of composite multidomain recovery indices such as the Recovery Efficiency Index. Randomized con- trolled trials integrating proprioceptive rehabilitation with cognitive-behavioral or mindfulness-based strategies may also help optimize multidimensional recovery and return-to-sport outcomes in athletes with patellofemoral pain syndrome.

  Dynamic proprioceptive training improves functional recovery in sprinters with patellofemoral pain: A randomized trial · 2026 · DOI

• Background/Objectives: Modifiable intrinsic factors such as foot posture, hallux mobility, dynamic balance, and body mass index (BMI) are widely assessed in athletic screening, but their reliability and interrelationships remain unclear.

  Reliability, Validity, and Clinical Interrelationships of Lower-Extremity Screening Measures in College Athletes · 2026 · DOI

• Although altered gait biomechanics have been reported in AKP, it remains unclear whether unilateral and bilateral AKP exhibit distinct biomechanical phenotypes, particularly in terms of interlimb asymmetry.

  Biomechanical phenotypes of unilateral versus bilateral anterior knee pain: evidence from walking kinematics, kinetics, and symmetry indices · 2026 · DOI

• In addition, because no group without hindlimb suspension was included, it remains unclear whether the observed reduction in ankle dorsiflexion range of motion was specifically attributable to the two hour daily immobilization period alone. Additionally, the development of contracture may vary depending on the interaction between immobilization duration and experimental period, which should be explored in subsequent investigations. Fifth, the histological assessment in this study was limited to the measurement of soleus muscle fiber cross-sectional area. Eighth, the immobilization period was fixed at two hours per day; however, it remains uncertain whether this duration represents the minimum threshold for inducing contracture.

  Joint Contracture Resulting From a Two-Hour Daily Joint Immobility: An Experimental Study in Rats · 2026 · DOI

• However, the scope of these findings is limited to training and performance on FMA-LE scoring using video-recorded cases. Therefore, caution is warranted when extrapolating these results to broader clinical assessment competence, hands-on examination skills, or clinical management decisions.

  Online versus offline Fugl-Meyer lower extremity training for physical therapy students: a randomized study · 2026 · DOI

• related to knee ligament injuries, with scores ranging from 0 to 100, where higher scores indicate better function (19). The IKDC Subjective Knee Form evaluates symptoms, daily activities, and sports function, with scores expressed as a percentage of the maximum possible score, where higher values indicate better knee function (20). Proprioception was assessed using the joint position sense (JPS) test with a standard universal goniometer. During the assessment, participants were positioned in a seated posture at the edge of the examination table with their eyes closed. To assess knee joint repositioning method was used. The examiner passively moved the knee to target angles of 15°, 30°, and 60° of flexion and joint position sense, the passive-to-active Frontiers in Sports and Active Living 02 frontiersin.org Nas et al. 10.3389/fspor.2026.1850922 maintained each position for 5 s. Participants were instructed to memorize the target position before the limb was returned to the starting position. They were then asked to actively reproduce the target angle, and the absolute error between the target and reproduced angles was recorded in degrees. Three trials were performed for each angle, and the mean error was used for analysis. Joint position sense is a valid method for assessing proprioceptive function in individuals with knee conditions (21). Dynamic balance was assessed using the Y-Balance Test (YBT). Participants were instructed to maintain balance on a single leg while reaching as far as possible in the anterior, posteromedial, and posterolateral directions. Reach distances (in centimeters) were measured and normalized to lower extremity length (22). Functional performance was assessed using the Single-Leg Hop Test which has demonstrated excellent test–retest reliability (ICC = 0.94) (23). Participants were instructed to start from a standardized position and perform a maximal forward hop, landing on the same limb and maintaining balance for at least 2 s. The hop distance was measured from the starting line to the heel of the landing foot. Trials were considered invalid if lost balance or touched the ground with the participants contralateral limb. Participants performed three successful trials for each limb, and the average hop distance (in centimeters) was used for analysis. Limb symmetry index (LSI) was calculated as (injured limb/uninjured limb) × 100. LSI values were used to describe inter-limb symmetry, with values of ≥90% considered indicative of acceptable symmetry (24, 25). 2.4 Statistical analysis All statistical analyses were performed using IBM SPSS Statistics version 26.0 (IBM Corp., Armonk, NY, USA). The normality of continuous variables was assessed using the Shapiro–Wilk test. Descriptive statistics were presented as mean ± standard deviation (SD) for continuous variables and frequency (percentage) for categorical variables. Comparisons between injured and uninjured limbs were conducted using paired samples t-tests. Bonferroni correction was applied for multiple paired comparisons. Pearson correlation analysis was performed the relationships between clinical symptoms, proprioception, dynamic balance, and functional performance variables after confirming normality assumptions. 95% confidence for correlation coefficients were calculated. Effect sizes for paired comparisons were calculated using Cohen’s dz and interpreted as small (0.2), medium (0.5), and large (0.8) (26). Statistical significance was set at p < 0.05.

  Inter-limb sensorimotor and functional performance asymmetries in elite wrestlers with unilateral knee injury · 2026 · DOI

• • Introduce early screening programs in schools to identify students with pes planus and related ankle or balance problems. • Provide awareness sessions and simple exercise programs to strengthen the foot, improve balance, and reduce fall risk among schoolchildren. • Conduct longitudinal studies with larger and more diverse student populations to confirm these findings and evaluate long-term outcome. 5 6 https://journals.e-palli.com/home/index.php/ajpehs Page Am. J. Phys. Educ. Health Sci. 4(1) 57-67, 2026 REFERENCES Açak, M. (2020). The effects of individually designed insoles on pes planus treatment. Scientific Reports, 10(1), 19715. Aenumulapalli, A., Kulkarni, M. M., & Gandotra, A. R. (2017). Prevalence of flexible flat foot in adults: a cross-sectional study. Journal of clinical and diagnostic research: JCDR, 11(6), AC17. Alahmri, F., Alsaadi, S., Ahsan, M., & Almousa, S. (2022). The effect of isokinetic hip muscle strength on normal medial longitudinal arch feet and pes planus. Journal of medicine and life, 15(9), 1164. Ateeque, A., Shabbir, S., Nadeem, T., Zubair, H., & Khizar, Z. (2024). Prevalence of Flatfoot in School-Going Children, Lahore. Journal of Health and Rehabilitation Research, 4(2), 745-749. Ayu, I. A. A. S. I., Suadnyana, A., Kadek, N. K. Y. F. N., Fridayani, Y., Made, I. M. D. P. I., & Prianthara, D. (2023). Association of foot posture and static balance among senior high school students in Bali, Indonesia as predictor of injury: A cross-sectional study. The Southeast Asian Journal of Tropical Medicine and Public Health, 54(Suppl. 2), 272–286. Babu, D., & Bordoni, B. (2020). Anatomy, bony pelvis and lower limb, medial longitudinal arch of the foot. In StatPearls. StatPearls Publishing. Bakırhan, S., Elibol, N., Özkeskin, M., & Özden, F. (2021). The relationship between knee-ankle muscle strength and performance tests in young female adults with flexible pes planus. Bulletin of Faculty of Physical Therapy, 26(1), 4. Barutcu, E., Paksoy, B., Selçuk, M., Karaca, O., & Yılmaz, K. (2024). Effects Of Pes Planus On Foot Pain, Low Back Pain And Balance İn Young Adult Individuals. Acıbadem Üniversitesi Sağlık Bilimleri Dergisi, 15(3), 240- 246. Birhanu, A., Nagarchi, K., Getahun, F., Gebremichael, M. A., & Wondmagegn, H. (2023). Magnitude of flat foot and its associated factors among school-aged children in Southern Ethiopia: an institution-based cross-sectional study. BMC Musculoskeletal Disorders, 24(1), 966. Chou, M.-C., Huang, J.-Y., Hung, Y.-M., Perng, W.-T., Chang, R., & Wei, J. C.-C. (2021). Flat foot and spinal degeneration: Evidence from nationwide populationbased cohort study. Journal of the Formosan Medical Association, 120(10), 1897-1906.

  Frequency of Pes Planus in Its Association with Ankle Pain and Risk of Fall Reported in School Students. Cross-Sectional Study · 2026 · DOI

• • The study was limited to students from selected schools, reducing the generalizability of findings. • Some school students had difficulty understanding the questionnaire items, which may have influenced their responses. • The cross-sectional design does not allow causal relationships to be established between pes planus, ankle pain, and fall risk. CONCLUSION The analysis revealed that there was a borderline relationship between FAAM and age, implying that the level of functional activity can be slightly different among age groups, but BMI and BBS had no significant relationship with age. Conversely, pes planus (PP) demonstrated a close and robust correlation with balance scores (BBS) at the categorical and the total levels, indicating that the superior physical performance is closely associated with a higher balance capability. None of the meaningful correlations were identified between FAAM and PP or between FAAM and BBS, which indicated that the self-reported functional ability was not directly correlated with performance or balance results.

  Frequency of Pes Planus in Its Association with Ankle Pain and Risk of Fall Reported in School Students. Cross-Sectional Study · 2026 · DOI

• history, and biomechanical characteristics may therefore improve safety and optimize long-term performance outcomes. to runner profile, training goals, trained Variations in plate stiffness, midsole foams, shoe mass, running speeds, and participant characteristics limited the ability to isolate the specific effects of carbon plates. Sample sizes were generally reducing generalizability. Moreover, factors such as foot strike pattern and prior CPS experience were not consistently reported, despite their potential influence on biomechanical responses. predominantly male, small and including Future research should prioritize standardized protocols, larger and more diverse samples, and longitudinal designs assessing adaptation over time. Comprehensive biomechanical joint moments, 3D kinematics, muscle analyses, activity, and plantar pressure, would help the mechanisms underlying CPS-induced gait modifications. Stratifying analyses by runner characteristics (e.g., performance level, habitual cadence) may also reveal subgroups that benefit most, or least, from CPS.

  Carbon plates in running shoes biomechanics: a systematic review and meta-analysis · 2026 · DOI

• Funding Despite including 16 studies, the number of meta-analyzable outcomes was smaller due to methodological heterogeneity. The author(s) declared that financial support was not received for this work and/or its publication. Frontiers in Sports and Active Living 14 frontiersin.org Martin et al. 10.3389/fspor.2026.1764338 Conflict of interest The author(s) declared that this work was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. artificial intelligence and reasonable efforts have been made to ensure accuracy, including review by the authors wherever possible. If you identify any issues, please contact us.

  Carbon plates in running shoes biomechanics: a systematic review and meta-analysis · 2026 · DOI

• The image obtained by static ultrasonography (US), despite being a validated measure to identify muscle thickness (MT), has a visualization capacity limited by the size of the transducer.

  Reliability and measurement error of the proximal, medial and distal portions of the vastuslateralis muscle thickness measured with extended field of view ultrasonography · 2022 · DOI

• Ultrasound imaging (USI) provides a visual means to explore muscle thickness throughout movement; however, USI functional-activation ratios (FARs) of the gluteal muscles during dynamic balance exercises have not been investigated.

  Ultrasound Imaging of the Gluteal Muscles During the Y-Balance Test in Individuals With or Without Chronic Ankle Instability · 2019 · DOI

• The precise aetiology of Patellofemoral Pain Syndrome (PFPS) remains unclear; however, the efficacy of employing hip abductor and lateral rotator muscle strengthening interventions in the rehabilitation of patients with PFPS has been previously documented.

  Strengthening the hip muscles in individuals with patellofemoral pain: what can be learned from the literature? · 2015 · DOI

• Although strength training and stretching programs have traditionally been the mainstay of patient treatment, there are no consensus recovery protocols for runners experiencing PFPS.

  A Review of the Management of Patellofemoral Pain Syndrome · 2013 · DOI

• The etiological mechanism of PFPS is poorly understood, however it is purported that biomechanical dysfunction of the patellofemoral joint leads to anterior knee pain and decreased function.

  Patellofemoral Pain Syndrome: A Critical Analysis of Current Concepts · 2002 · DOI

• BACKGROUND: Although the cause of PFJ pathology is believed to be related to elevated joint stress (force per unit area), this hypothesis has not been adequately tested and causative mechanisms have not been clearly defined.

  Patellofemoral stress during walking in persons with and without patellofemoral pain · 2002 · DOI

• PURPOSE: Although closed (CKCE) and open (OKCE) kinetic chain exercises are used in athletic training and clinical environments, few studies have compared knee joint biomechanics while these exercises are performed dynamically.

  Biomechanics of the knee during closed kinetic chain and open kinetic chain exercises · 1998 · DOI

• Cushioned insoles have the potential to lower plantar pressures beneath the hallux and possibly reduce pain, but their clinical effectiveness has not been investigated.

  Cushioned Insoles for First Metatarsophalangeal Joint Osteoarthritis: Protocol for the SOLE Randomised Controlled Trial · 2026 · DOI

• These findings suggest that asymmetrical self-reported knee pain may be related to underlying strength imbalances in individuals with knee osteoarthritis and warrant further investigation regarding its potential clinical relevance.

  Lower Limb Strength Asymmetry is Associated With Stair Ambulatory Pain in Individuals With or at Risk for Knee Osteoarthritis · 2026 · DOI

• Moreover, there is no consensus in the literature regarding the influence of contraction initiation (pre-activation or passive start), although it could alter the interaction between fascicles and the tendon.

  Effect of joint velocity and pre-activation on the torque-fascicle length relationship of the vastus lateralis · 2026 · DOI

• Fascicle operating length during dynamic tasks is often compared to the isometric torque-length relationship, but there is a lack of evidence regarding the influence of joint velocity on optimal fascicle length.

  Effect of joint velocity and pre-activation on the torque-fascicle length relationship of the vastus lateralis · 2026 · DOI

• Given its rarity, congenital patellar agenesis is seldom encountered in clinical practice, and its presentation is sparsely recorded in existing studies.

  THE ABSENCE OF UNILATERAL PATELLA IN A 7-YEAR-OLD BOY: A RARE CASE REPORT · 2026 · DOI

• Prolonged running load may be accompanied by changes in the morphogeometric status of the foot; however, the dynamics of a set of plantographic foot parameters after a half-marathon distance remain insufficiently studied.

  Short-term changes in plantographic foot parameters in male runners after running load · 2026 · DOI

• Although boots are commonly used for many occupational and daily activities, their effects on joint mechanics and injury risk are not well understood.

  How boots affect lower limb joint contact forces during walking compared with casual footwear: a musculoskeletal modelling study · 2026 · DOI

Most-cited papers in Lower Extremity Biomechanics and Pathologies

• Biomechanics of the knee during closed kinetic chain and open kinetic chain exercises · Medicine & Science in Sports & Exercise · 1998 · 433 citations
• Physical Therapy for Patellofemoral Pain · The American Journal of Sports Medicine · 2002 · 343 citations
• Technical Errors during Medial Patellofemoral Ligament Reconstruction Could Overload Medial Patellofemoral Cartilage · The American Journal of Sports Medicine · 2006 · 338 citations
• Orthopedic Complications of Overweight in Children and Adolescents · PEDIATRICS · 2006 · 314 citations
• Patellofemoral stress during walking in persons with and without patellofemoral pain · Medicine & Science in Sports & Exercise · 2002 · 245 citations
• Forefoot Strikers Exhibit Lower Running-Induced Knee Loading than Rearfoot Strikers · Medicine & Science in Sports & Exercise · 2013 · 245 citations
• The Anatomy and Isometry of Themedial Patellofemoral Ligament · The American Journal of Sports Medicine · 2004 · 236 citations
• Muscle, Ligament, and Joint-Contact Forces at the Knee during Walking · Medicine & Science in Sports & Exercise · 2005 · 227 citations
• Intrinsic Risk Factors for Inversion Ankle Sprains in Male Subjects: A Prospective Study · The American Journal of Sports Medicine · 2005 · 211 citations
• Clinical Outcomes and Predictive Factors for Failure With Isolated MPFL Reconstruction for Recurrent Patellar Instability: A Series of 211 Reconstructions With a Minimum Follow-up of 3 Years · The American Journal of Sports Medicine · 2019 · 201 citations

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• Effects of neuromuscular training on pain, physical function, balance, muscle strength, and lower limb kinematics in individuals with patellofemoral pain: a systematic review and meta-analysis of randomized controlled trials · BMC Sports Science, Medicine and Rehabilitation · 2026
• Electromyographic activation of extrinsic and intrinsic foot muscles during nine different foot exercises in women with hallux valgus: a cross-sectional comparative study · BMC Musculoskeletal Disorders · 2026
• STRESS FRACTURES OF THE FEMORAL NECK IN PHYSICALLY ACTIVE INDIVIDUALS: DIAGNOSTIC CHALLENGES AND MANAGEMENT · International Journal of Innovative Technologies in Social Science · 2026
• The ETSPR-Delta 7783 Multimodal Chassis Protocol · Zenodo (CERN European Organization for Nuclear Research) · 2026
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