ECSS Paris 2023: OP-BM18
INTRODUCTION: Between 1990 and 2022, the global prevalence of obesity in youth increased from 1.9% to 8.1% [1]. Obesity may change the muscle architecture, enhance the muscle function [2], and increase the Achilles tendon (AT) thickness and stiffness. These adaptations can produce an imbalance between muscle and tendon, increasing the injury risk in youth [3]. Biological maturation induces similar muscle and tendon adaptations. The study aims to investigate the interaction between biological maturation and obesity on the gastrocnemius medialis (GM) architecture and function, and the AT structure and mechanical properties METHODS: 48 youth were divided into four groups: normal-weight (NW) pre-age-to-peak height velocity (APHV) (6F/6M; APHV: -2.54±0.92 years), NW post-APHV (6F/6M;APHV:2.14±0.97 years), youth with obesity (OB) pre-APHV (6F/6M;APHV: -2.37±1.03 years, and OB post-APHV (6F/6M;APHV:1.66±0.69 years). Assessment included: i) GM architecture (thickness, pennation angle, and fascicle length); II) Plantar flexors (PF) function (maximal isometric voluntary contraction [MIVC] and rate of force development [RFD]). III) AT structure (AT: tibia length [AT: TL] ratio) and AT cross-sectional area. IV) AT mechanical properties (stiffness, strain, and Young’s modulus). Holm-Bonferroni post-hoc test followed significant ANCOVA effects (time [APHV]×groups [obesity-non-obesity]), with effect size calculated (partial eta squared [η²ₚ]). Approved by the Ethics Committee (code:14-26022024) RESULTS: A time and group effect, was observed, with greater GM thickness (p<0.0001,η²ₚ=0.44;p<0.0001;η²ₚ=0.40), pennation angle (p=0.005;η²ₚ=0.17; p<0.0001,η²ₚ=0.30), and fascicle length (p<0.0001;η²ₚ=0.28;p=0.0008;η²ₚ=0.10) in post-APHV compared with pre-APHV, and in OB compared with NW, respectively. A time effect was observed with a greater PF MIVC (p<0.0001;η²ₚ= 0.53), RFD50 (p<0.0001;η²ₚ= 0.36), and RFD200 (p<0.0001;η²ₚ= 0.41) in the post-APHV vs. Pre-APHV groups. A group effect was evidenced by a greater AT: TL ratio (p=0.019;η²ₚ= 0.06) in the NW pre-APHV vs. OB pre-APHV group. A time effect was evidenced by a greater AT CSA (p= 0.008;η²ₚ= 0.11) in NW post-APHV vs. Pre-APHV group. A time (p=0.003;η²ₚ= 0.17) and group effect (p=0.01;η²ₚ= 0.07) were evidenced for AT stiffness. Time effect was observed with a greater AT stiffness in the post-APHV vs. Pre-APHV group, and the group effect in the OB pre-APHV vs. the NW pre-APHV group. A time (p=0.0001;η²ₚ= 0.28) was shown with a greater AT Young’s modulus in the post-APHV vs. Pre-APHV groups. An interaction effect (p=0.01;η²ₚ= 0.13) was shown with a lower strain for the OB post-APHV vs. other three groups CONCLUSION: Biological maturation and obesity drive changes in muscle architecture. Biological maturation enhances muscle function and increases AT thickness and Young’s modulus, while obesity is associated with a lower AT:TL ratio. Both factors promote greater tendon stiffness and lower strain, potentially altering tendon loading in youth with obesity
Read CV Mauricio InostrozaECSS Paris 2023: OP-BM18
INTRODUCTION: Selective dorsal rhizotomy (SDR) is a neurosurgical procedure used to reduce lower-limb spasticity in children with cerebral palsy (CP). While short- and medium-term outcomes are well documented, evidence on very long-term gait outcomes remains limited. This study investigated changes in 2D gait parameters at 1, 3, 10, 20, and 30 years following SDR, compared with typically developing (TD) adults. In addition, 3D gait parameters were compared between adults with CP at 30 years post-SDR and TD adults. METHODS: This prospective follow-up study included gait data collected preoperatively and at 1, 3, 10, 20 [1-4], and 30 years following SDR. Of the fourteen individuals with CP who participated in the original study [1], twelve adults were available for the 30-year follow-up. Gait analyses were performed at a self-selected speed along a 20 m walkway and captured using a 3D motion analysis system (Vicon, Oxford Metrics, UK). Standard lower-body Plug-in-Gait models were used for both 2D and 3D analyses. Seventeen kinematic parameters, the gait deviation index (GDI), and non-dimensional temporal–distance parameters (normalised to leg length) were analysed. Changes over time and differences between adults with CP and TD adults were examined using mixed-model two-way ANOVA, with Tukey post hoc tests applied where appropriate. Statistical significance was set at p < 0.05. RESULTS: Twelve adults with spastic diplegic CP who underwent SDR at a mean age of 7 ± 3 years participated in the study. Significant improvements in knee range of motion (ROM) were observed at 1 year (p = 0.049) and 3 years (p = 0.006) post-SDR, and in hip ROM at 1 year post-SDR (p = 0.002). These improvements, along with other gait parameters, remained stable up to 30 years post-SDR. Normalised step length (p = 0.16) and cadence (p = 0.07) remained stable over time, while normalised walking speed remained slower in adults with CP compared to TD adults (p = 0.024), consistent with findings at 10 and 20 years post-SDR. At 30 years post-SDR, 3D gait analysis revealed differences in 9 of 17 kinematic parameters between adults with CP and TD adults, primarily involving pelvic kinematics, hip extension, knee flexion, and ankle plantar flexion (p < 0.01). Despite these differences, the mean GDI (74 ± 14) remained within the functional range. CONCLUSION: When applied to appropriately selected children with spastic diplegia, SDR results in long-term improvements in gait. Although improvements in gait mainly occur within the first three years following surgery, gait parameters remain stable for up to 30 years post-SDR. Despite kinematic gait differences compared with TD adults, overall gait function remains within a functional range, which emphasises the long-term efficacy of SDR. References 1. Vaughan et al. Pediatr Neurosci 1988:14(6):297-300 2. Vaughan et al. J Neurosurg. 1991:74(2):178-184 3. Subrmanian et al. J Neurosurg. 1998:88(6):1014-1019 4. Langerak et al. J Neurosurg Pediatr. 2008;1(3):180-186
Read CV Robert LambertsECSS Paris 2023: OP-BM18
INTRODUCTION: This investigation evaluated the differential effects of load magnitude and distribution symmetry on trunk neuromuscular activation patterns, vertical ground reaction forces (vGRF), and estimated lumbar spine compression during overground ambulation in individuals with chronic low back pain (CLBP) compared to asymptomatic controls. METHODS: Thirty male participants (15 CLBP, 15 controls; age range: 23–28 years) completed walking trials under four experimental conditions: symmetrical and asymmetrical load carriage at 10% and 20% body weight (BW). Bilateral surface electromyography quantified activation from seven trunk muscles (rectus abdominis, external oblique, internal oblique, latissimus dorsi, lumbar erector spinae, multifidus) and the thoracolumbar fascia region, normalized to maximum voluntary isometric contractions (%MVIC). Force platforms recorded vGRF synchronized with heel-strike events. A repeated-measures ANOVA with Bonferroni post-hoc corrections analyzed main effects and interactions of load configuration and magnitude. RESULTS: Asymmetrical loading at 20% BW elicited significantly greater peak vGRF relative to symmetrical loading (Δ = 47.3 N, p < 0.001), demonstrating a significant load magnitude × configuration interaction (p = 0.004, ηp² = 0.26). CLBP participants exhibited consistently elevated trunk muscle activation throughout the gait cycle (peak: 37% vs. 30% MVIC in controls; p < 0.001, Cohen's d = 1.68), characterized by maximal recruitment at shortened muscle lengths and 24% diminished activation at optimal length (95% CI: 18.2–29.8%). The lumbar erector spinae and multifidus demonstrated highest activation during asymmetrical 20% BW loading in CLBP participants (0.282 and 0.263 %MVIC, respectively), reflecting compensatory neuromuscular strategies. CONCLUSION: Asymmetrical load carriage imposes disproportionately elevated mechanical and neuromuscular demands that are substantially amplified in CLBP populations. These findings provide empirical support for rehabilitation interventions emphasizing optimal load distribution and motor control restoration to mitigate compensatory strain and enhance trunk stabilization capacity.
Read CV Wissem DhahbiECSS Paris 2023: OP-BM18