ECSS Paris 2023: CP-BM06
INTRODUCTION: Back pain (BP) affects up to 85% of adults [1] and over 40% of 17-year-old girls [2]. BP can impair performance, quality of life and overall health [3]. Prolonged sitting has been linked to structural spinal changes [4] and alterations in intervertebral discs are considered a potential mechanism in the development of BP [5]. The aim of this study was to examine whether a preventive, posture-specific training program (PSTP) over three weeks can improve trunk inclination (TRIN) in healthy children (CH) across different everyday positions (POS). METHODS: 194 CH participated, and at T0 their posture was measured using rasterstereography during standing (POS1), sitting while writing (POS2), and normal sitting (POS3). The intervention group (IG, n=109) completed a three-week PSTP at school and at home; the control group (CG, n=84) followed their usual routine. The same measurements were taken after three weeks (T1), two (T2), seven (T3), and eleven months (T4). RESULTS: 53 CH in the IG and 46 CH in the CG completed all measurements. For POS2, post hoc tests of a Mixed ANOVA for TRIN revealed significant differences in the IG from T0 to T1 (p<.001, Cohen's d=0.87), T0 to T2 (p=.016, Cohen's d=0.74), T0 to T3 (p<.001, Cohen's d=0.93), T0 to T4 (p<.001, Cohen's d=0.93) and in the CG from T1 to T4 (p=.003, Cohen's d=0.61). The main results for TRIN in POS1 and POS3 showed no significant differences (p>.05). CONCLUSION: Given the high prevalence of BP and the amount of time CH spend sitting at school, these findings provide task-specific insights into postural adaptation. PSTP led to short- and long-term improvement in TRIN when sitting while writing in the IG. Although no general effects were observed, this task-specific adaptation may be relevant, as even small changes in angle can influence spinal loading and cumulative mechanical stress. Thus, early optimization of postural control may contribute to musculoskeletal health, BP prevention, and the foundation of efficient movement patterns. REFERENCES [1] Raspe, H. (2012). Themenheft 53 „Rückenschmerzen“. Robert-Koch-Institut (RKI). https://doi.org/10.25646/3164 [2] Ellert, U., Neuhauser, H. & Roth-Isigkeit, A. (2007). Schmerzen bei Kindern und Jugendlichen in Deutschland: Prävalenz und Inanspruchnahme medizinischer Leistungen. Bundesgesundheitsblatt - Gesundheitsforschung - Gesundheitsschutz, 50(5–6), 711–717. [3] Pericot-Mozo, X., Suñer-Soler, R., Reig-Garcia, G., Patiño-Masó, J., Sitjar-Suñer, M., Masià-Plana, A. & Bertran-Noguer, C. (2024). Quality of Life in Patients with Chronic Low Back Pain and Differences by Sex: A Longitudinal Study. JPM, 14(5), 496. [4] Drzaƚ-Grabiec, J., Snela, S., Rykaƚa, J., Podgórska, J. & Rachwal, M. (2015b). Effects of the sitting position on the body posture of children aged 11 to 13 years. Work, 51(4), 855–862. [5] Billy, G. G., Lemieux, S. K. & Chow, M. X. (2014). Changes in Lumbar Disk Morphology Associated With Prolonged Sitting Assessed by Magnetic Resonance Imaging. PM&R, 6(9), 790–795.
Read CV Kathrin SchmalzlECSS Paris 2023: CP-BM06
INTRODUCTION: The latissimus dorsi (LD) exhibits a broad architecture and multiple lines of action and, according to biomechanical muscle models, enables its contribution to different shoulder movements such as extension and horizontal abduction. Previous studies have shown that large muscles may present region-specific activation depending on task demands and joint kinematics, particularly when assessed using high-density electromyography (HDEMG) [1,2]. However, evidence regarding how changes in shoulder movement planes during rowing exercises affect the spatial distribution and magnitude of LD activation remains limited. Therefore, this study aimed to compare the activation barycenter position and neural demand of the LD during close-grip and wide-grip rowing exercises. METHODS: Fourteen resistance-trained men performed three sets of 12-repetition maximum of a close-grip row (CGR) and a wide-grip row (WGR) on separate days. LD muscle activity was recorded using a 32-electrode HDEMG array. The spatial distribution of activation was quantified by the normalized position of the activation barycenter along the superior–inferior axis of the LD, while neural demand was assessed by the root mean square amplitude normalized (RMS%) to maximal voluntary isometric contraction (MVIC). Linear mixed models were applied for statistical analyses. RESULTS: The activation barycenter was consistently positioned more inferiorly during CGR (≈ 23% of LD length) compared with WGR (≈ 13%) across all repetitions and sets (p < 0.001; η²p ≈ 0.41), indicating greater recruitment on the lower LD region. RMS% was significantly higher in CGR (≈ 60% of MVIC) than in WGR (≈ 36%) for all repetitions and sets (p < 0.001; η²p ≈ 0.36–0.37). CONCLUSION: Changes in shoulder movement planes during rowing exercises influence both the spatial distribution and magnitude of latissimus dorsi activation. The close-grip row elicits a more inferior activation pattern and greater neural demand than the wide-grip row, reinforcing the concept of task-dependent regional muscle activation described in previous HDEMG studies [2,3]. These findings highlight the relevance of exercise configuration for maximizing LD recruitment and provide mechanistic insight into region-specific muscle activation during resistance exercise.
Read CV Thiago MattaECSS Paris 2023: CP-BM06
INTRODUCTION: Deadlift performance requires high hip extension torque while maintaining lumbar stability, and insufficient control of lumbar alignment may increase spinal loading and injury risk. Previous studies have shown that lumbar lordosis angle (LLA) decreases as load increases. However, whether load-dependent reductions in LLA are associated with hip extension torque remains unclear. The aim of this study was to examine the relationship between LLA displacement and hip extension torque during deadlifts performed at 60% and 90% of one-repetition maximum (1RM). METHODS: Twelve healthy young male participants performed deadlifts at 60% and 90%1RM. Three-dimensional kinematic data were collected using an optical motion capture system (VICON MX). Six reflective markers were placed on selected spinous processes to construct a sagittal-plane trunk model consisting of six rigid segments. Hip extension torque was separately assessed using an isometric dynamometer (CONTREX MJ). Trunk kinematics and joint kinetics were calculated using two-dimensional inverse dynamics in MATLAB (MathWorks). RESULTS: The minimum LLA during deadlift was 165.6 ± 6.5° at 60% 1RM and 161.6 ± 6.9° at 90% 1RM (P<0.05). The angular displacement from neutral (T-pose) to minimum LLA increased by 4.0 ± 2.3° with increasing load. Maximum hip extension torque was 388.3 ± 47.7 Nm (5.4 ± 0.6 Nm/kg). A non-significant correlation was found between 1RM (1RM/kg) and LLA displacement (R² = 0.05). A significant negative correlation was found between maximum hip extension torque and LLA displacement (R² = 0.63). CONCLUSION: Therefore, increased lumbar flexion was not explained by the magnitude of 1RM, but was suggested to be associated with maximal hip extension torque capacity. These findings suggest that lumbar alignment during high-load deadlift may reflect the balance between hip extension torque and trunk stabilization demands.
Read CV Kazuma ShojiECSS Paris 2023: CP-BM06