ECSS Paris 2023: OP-BM24
INTRODUCTION: Contemporary best-practice guidance recognises patellofemoral pain (PFP) as a multifactorial condition requiring clinically targeted rehabilitation rather than one-size-fits-all approaches (Neal et al., 2024). Existing studies typically focus on isolated muscles or limited biomechanical domains, restricting whole-chain interpretation of neuromechanical coordination that may characterise PFP during running conditions (Muniz, et al 2023). Therefore, this study aims to investigate the neuromechanical mechanisms in PFP during running, to inform future intervention strategies. METHODS: Seventeen runners with PFP were compared with 17 injury-free controls during overground running. Institutional ethics approval was obtained. Three-dimensional kinematics (240 Hz), ground reaction forces (1000 Hz), and surface electromyography (EMG) from lower-limb and trunk muscles were collected. EMG amplitude was normalised to maximal voluntary isometric contractions. Joint angles and moments at the ankle, knee, hip, pelvis and thorax, alongside peak muscle activation, were extracted across stance (0-40%) and terminal swing (85–100%). Between-group differences were assessed using independent t-tests with Cohen’s d and 95% confidence intervals. Subgroup effects of injury severity and kinesiophobia, within the PFP cohort were examined using one-way ANOVA and raincloud visualisation. RESULTS: Stance (0-40%) Compared with controls, the PFP group exhibited reduced peak tibialis anterior activation (38.5 ± 20.2 vs 63.2 ± 21.6 %max; p = 0.002, d = 1.18) and greater peak gluteus maximus activation compared to controls (155.3 ± 11.1 vs 96.3 ± 34.6 %max; p < 0.001, d = 2.30). No significant between-group differences were observed in sagittal-plane and frontal plane joint moments or kinematics (all p > 0.05). Terminal swing (85–100%) The PFP group demonstrated no between-group differences in knee, hip, or thoracic sagittal kinematics, joint moments, or proximal and distal muscle activation (all p > 0.05). Subgroup Analysis For all significant variables, ANOVA subgroup analyses within the PFP cohort showed no effects of symptom severity or kinesiophobia (p > 0.05), with raincloud plots demonstrating substantial overlap and no graded patterns. CONCLUSION: In stance, the PFP had a lower activation peak of TA, suggesting reduced ankle loading/control response during initial contact. Peak GMax activation was higher in PFP group suggesting greater reliance on a hip extensor strategy contributing to whole-limb support. No differences during subgroup analysis supports the idea that these PFP mechanical characteristics may be present across a broad range of clinical presentations.
Read CV Joseph LiddyECSS Paris 2023: OP-BM24
INTRODUCTION: Temporal gait parameters, including contact time (CT), flight time (FT), and duty factor (DF), characterize running style and are associated with performance and musculoskeletal loading. Lower-limb strength, leg stiffness, and flexibility are recognized determinants of running mechanics, yet their integrated contributions and interaction pathways remain unclear, particularly whether strength influences gait timing directly or indirectly via stiffness modulation. This study quantified the associations of lower-limb maximal strength, leg stiffness (Kleg), and joint flexibility with temporal gait parameters, evaluated stiffness-mediated pathways linking strength to gait, and explored sex-specific interaction effects using multivariate regularized modelling. METHODS: Sixty-nine recreational runners (38 male, 31 female) completed three laboratory sessions assessing overground running biomechanics, isometric mid-thigh pull strength, and lower-limb joint range of motion. Temporal gait parameters and mass-normalized Kleg were obtained from markerless 3D motion capture during running at controlled speed. Peak force (PF) and rate of force development (RFD) were derived from force-platform IMTP testing. Elastic Net regression examined associations between neuromuscular variables and gait parameters while controlling for speed. Bootstrap mediation analyses tested indirect PF effects through Kleg. RESULTS: No sex differences were observed in CT, FT, or DF. Elastic Net models explained substantial variance (Partial R² = 0.447–0.515). Greater PF and Kleg were associated with shorter CT, longer FT, and lower DF, indicating a more aerial running pattern, while RFD showed no predictive relevance. Hip extension ROM predicted longer CT, with significant sex interactions demonstrating stronger flexibility–gait associations in males. Mediation analysis showed PF effects were largely indirect, with Kleg accounting for 49–63% of total associations with temporal gait parameters. CONCLUSION: Lower-limb strength, stiffness, and flexibility collectively explain a large proportion of variability in running temporal structure. The findings support a hierarchical neuromechanical model in which maximal force capacity influences gait behavior primarily through stiffness modulation rather than direct mechanical action. Sex-dependent flexibility effects indicate distinct regulation strategies between male and female runners. From an applied perspective, these results suggest that training interventions targeting stiffness development may more effectively alter gait timing than strength enhancement alone, and that flexibility modulation strategies should consider sex-specific responses. Overall, this work provides integrative mechanistic insight to inform individualized biomechanical optimization for performance and injury-risk management.
Read CV Fei LiECSS Paris 2023: OP-BM24
INTRODUCTION: Patellofemoral pain (PFP) is a prevalent overuse injury in runners. While altered lower limb biomechanics are considered primary risk factors, most existing studies utilize cross-sectional designs that assess patients who are already in pain. This makes it difficult to distinguish whether observed biomechanical abnormalities are the cause of the injury or compensatory strategies resulting from pain. To address this gap, this study aimed to identify biomechanical risk factors by analyzing the pre-pain phase during a continuous 5 km run, comparing runners with PFP to healthy controls. METHODS: Seventeen runners with PFP and 17 healthy controls, matched for sex, age, and weekly running distance, participated in the study. All participants performed a continuous 5 km running test. Kinematic and kinetic data were collected every 1 km using a markerless motion capture system (Theia3D) and force plates. For the PFP group, the pre-pain phase was defined as the kilometer immediately preceding the first report of clinically meaningful pain (VAS score >= 2). Data from the corresponding kilometer in the matched control group were used for comparison. Independent t-tests or Mann-Whitney U tests were used to analyze differences in peak joint angles, moments, angular impulses, and joint work during the stance phase. RESULTS: In the pre-pain phase, PFP runners exhibited distinct biomechanical deficits compared to controls. At the knee joint, PFP runners demonstrated a significantly lower peak adduction moment (p=0.014) and a higher coronal plane net angular impulse (p=0.041). At the ankle joint, PFP runners showed significantly higher net angular impulses in the sagittal (p=0.001), coronal (p=0.006), and transverse (p=0.001) planes. Furthermore, PFP runners exhibited reduced ankle peak inversion (p=0.030) and internal rotation moments (p=0.007), but increased external rotation moments (p=0.027). No significant differences were found in hip joint kinetics or angular impulses. CONCLUSION: PFP runners show decreased adduction moments and increased cumulative abduction loads. This is accompanied by excessive dynamic output at the ankle and altered rotational control. These findings suggest deficits in ankle control may transfer excessive loads to the knee, contributing to the development of PFP. Interventions for PFP should consider targeting ankle-knee coordination and strengthening to mitigate these pre-symptomatic risk factors.
Read CV Huijuan ShiECSS Paris 2023: OP-BM24