ECSS Paris 2023: OP-BM19
INTRODUCTION: Eccentric hamstring exercises are widely used in injury prevention and performance training, and exercise- and region-specific differences in hamstring activation have been reported. However, how neuromuscular activation is continuously modulated across the joint range of motion, and whether such modulation differs between eccentric exercise tasks and muscle regions, remains poorly understood. Therefore, this study examined angle-dependent hamstring activation patterns during two eccentric exercises and assessed task- and region-specific modulation. METHODS: Twenty-five healthy, physically active males performed eccentric hip extension (HE) and incline Nordic hamstring exercise (INHE). Surface EMG was recorded from the biceps femoris long head and semitendinosus at proximal and distal regions during the eccentric phase, synchronized with joint angle data. EMG amplitude was normalized and analysed using linear mixed-effects models, with joint angle treated as a continuous predictor. Fixed effects included joint angle, exercise task, muscle region, and their interactions, with participant as a random effect. RESULTS: Across exercises and muscle regions, hamstring activation increased progressively with joint angle during the eccentric phase (β = 0.042 %MVIC·deg⁻¹, p < 0.001). However, significant task- and region-specific modulation was observed. A significant Angle × Task interaction indicated a steeper overall activation–angle relationship during INHE compared with HE (β = 0.011 %MVIC·deg⁻¹, p < 0.001). Importantly, this modulation differed by muscle region. During INHE, distal regions of both muscles demonstrated markedly steeper angle-dependent increases compared with proximal regions (e.g., distal biceps femoris: Δβ ≈ −0.115 %MVIC·deg⁻¹ relative to HE, p < 0.001), whereas regional differentiation was attenuated during HE. Significant three-way interactions (Angle × Task × Region, all p < 0.001) confirmed that exercise-specific neuromuscular control strategies emerged primarily at larger joint angles. CONCLUSION: Eccentric hamstring exercises are characterized by distinct, task-dependent and region-specific neuromuscular control strategies across the joint range of motion. The pronounced distal activation observed during INHE at increasing joint angles suggests exercise-specific demands on regional hamstring function, potentially reflecting greater lengthening requirements and joint torque demands as the movement approaches end range. These findings extend previous task- and region-based comparisons by demonstrating how hamstring activation patterns evolve dynamically across movement, providing a mechanistic link between exercise selection and joint-angle–specific loading. From a practical perspective, such angle-dependent regional modulation may be relevant for optimizing eccentric exercise selection and progression in injury prevention and performance-oriented training.
Read CV Yanan YOUECSS Paris 2023: OP-BM19
INTRODUCTION: Athletes diagnosed with attention deficit hyperactivity disorder (ADHD) may be at risk of developing lower limb fractures or sprains due to the deficiency in motor control, which depends on the quality of sensorimotor function (Ruiz-Goikoetxea et al., 2018). Therefore, there is room to evaluate the sensorimotor abilities of the ankle joint in athletes with ADHD, in order to clarify the relationship between a form of central nervous system function and the sensorimotor acuity around the ankle joint and ankle stability. METHODS: Sample population included 103 participants divided into three groups, i.e., diagnosed (n=28) or suspected (n=32) with ADHD and a control group (n=33). Two tests were performed to assess the participants' sensorimotor acuity: 1. Joint position reproduction (JPR) test; 2. Active movement extent discrimination (AMEDA) test. RESULTS: Athletes diagnosed or suspected with ADHD had a significantly lower ankle movement discriminative ability compared to controls, i.e., 0.656±0.046 vs. 0.643±0.062 vs. 0.568±0.074 vs. respectively for the AMEDA test (WB condition) whereas, no significant difference was found between the three groups in the two inversion angles (10° and 30°) for absolute error, exact error and relative error of the dominant (right) leg in the JPR test (NWB condition). CONCLUSION: In individuals diagnosed with ADHD, sensory processing in general (e.g., sight, sound, touch etc.) including balance (vestibular stimuli) and body awareness (proprioception) may be impaired due to sensory dysregulation ( Li et al., 2023). Following Gillberg's statement (Gillberg, 2003): perception must be included in any assessment model for participants with ADHD, as part of the assessment of motor control. However, the main emphasis in the literature concerns the assessment of proprioceptive ability in the upper extremities, due to the possible connection to impaired fine motor skills and with an emphasis on writing. Therefore, based on the preliminary results of the current study, the ability to integrate sensorimotor information is impacted in the upright standing position, i.e., under gravity demands. This implies, that the AMEDA protocol could be used as a tool in the population diagnosed with ADHD to support further understanding and potential for enhancement of motor abilities in this group. References: Gillberg, C. (2003). Deficits in attention, motor control, and perception: a brief review. Arch Dis Child, 88(10), 904-910. https://doi.org/10.1136/adc.88.10.904 Li, J., Wang, W., Cheng, J., Li, H., Feng, L., Ren, Y., Liu, L., Qian, Q., & Wang, Y. (2023). Relationships between sensory integration and the core symptoms of attention-deficit/hyperactivity disorder: the mediating effect of executive function. Eur Child Adolesc Psychiatry, 32(11), 2235-2246. https://doi.org/10.1007/s00787-022-02069-5 Ruiz-Goikoetxea, M., Cortese, S., Aznarez-Sanado, M., Magallon, S., Alvarez Zallo, N., Luis, E. O., de Castro-Manglano, P., Soutullo, C., & Arrondo, G. (2018). Risk of unintentional injuries in children and adolescents with ADHD and the impact of ADHD medications: A systematic review and meta-analysis. Neurosci Biobehav Rev, 84, 63-71. https://doi.org/10.1016/j.neubiorev.2017.11.007
Read CV Smadar PelegECSS Paris 2023: OP-BM19