ECSS Paris 2023: OP-BM14
INTRODUCTION: Aging is associated with a reorganization of neuromuscular control, reflected in changes in spinal motor output (1). The Center of Activity (CoA), an EMG-derived measure of spinal activation, represents the temporal distribution of neuromuscular activity throughout the gait cycle (2). Evidence suggests that aging is linked to a posterior shift in lumbar CoA, reflecting delayed neuromuscular activation compared to younger adults (2). This delay in spinal motor output may contribute to an increase in external work and power of the center of mass (Wext & PCOM) during walking in older adults (3). While strength is often considered a determinant of gait mechanics, differences in motor strategies can occur independently of maximal force capacity. Physical activity (PA) may mitigate these effects by preserving neuromuscular coordination. This study examines the impact of PA level on spinal motor output and gait biomechanics in young and older adults. METHODS: Fifty-nine participants (31 young, 29 older adults) were categorized as more or less active via the Global Physical Activity Questionnaire (GPAQ). Gait analysis was conducted at 1.11 m·s⁻¹ on an instrumented treadmill, measuring kinematics, kinetics, and EMG of 12 lower-limb muscles. Wext and PCOM were computed. Isometric maximal voluntary torque (IMVT) of the knee and ankle extensors was assessed, and spinal motor output analyzed using EMG-based spinal maps. A mixed-effects model evaluated age and activity level effects. RESULTS: Spinal maps showed a lower lumbar CoA (p < 0.001) and a reduced lumbar-sacral CoA difference (p < 0.01) in less active older adults, suggesting altered neuromuscular coordination. While older adults exhibited reduced IMVT in the knee and ankle extensors (p < 0.001), no significant differences were observed in IMVT based on PA level. Despite these neuromuscular differences, Wext was higher (p < 0.001) in less active older adults, indicating increased mechanical demand. Additionally, W₁⁺, the first peak of PCOM corresponding to weight acceptance, was higher in this group (p < 0.001). CONCLUSION: Less active older adults exhibit a posterior lumbar CoA shift, reflecting delayed spinal motor output compared to more active older adults and both young groups. These neuromuscular changes coincide with higher Wext and altered PCOM (W₁⁺), indicating greater mechanical demand. Interestingly, despite differences in motor strategy, IMVT of the knee and ankle extensors did not differ across PA groups, suggesting that strength alone does not dictate gait adaptations. Physical activity may help preserve neuromuscular efficiency and reduce the mechanical cost of walking in aging. 1. Dewolf AH, et al. J Neurophysiol. 2019. 2. Avaltroni P, et al. Frontiers in Physiology. 2024. 3. Dewolf AH, et al. Applied Sciences. 2022
Read CV Mario Nunez-LisboaECSS Paris 2023: OP-BM14
INTRODUCTION:
Exercise interventions have the potential to enhance quality of life and to improve physical fitness and balance in brain tumor patients (1-3). Cognitive complaints commonly occur in brain tumor patients (4). However, direct effects of exercise interventions and/or cognitive impairment on gait cycle characteristics have not been reported, yet. This pilot-study is part of a broader investigation to evaluate effects of exercise on balance and gait and examines how additional cognitive load while walking in a real-time virtual environment impacts gait characteristics in brain tumor patients and their caregivers.
METHODS:
7 patients (4f/3m 50±15y, 175±8cm, 72±14kg) and 5 caregivers (4f/1m 44±18y, 169±5cm, 81±16kg) participated performing a walking test on the GRAIL-system. Ground reaction forces were measured separately for both feet as well as kinematics of two markers attached to each foot. Two different conditions were used, a normal gait (NG) with and without an additional cognitive task (CT-Stroop-test with color-denoting words) while walking on a treadmill with constant speed. Step length and width (SL, SW) as well as ground contact time (GCT), swing phase time (SP) were derived for analysis. Statistical analysis for within subject condition (NG vs. CT) was performed using the Wilcoxon tests (alpha=.05). Effect sizes were interpretated using Cliffs’s delta (negligible <0.15; 0.15 ECSS Paris 2023: OP-BM14
INTRODUCTION: The prevalence of type 2 diabetes (T2D) is increasing, placing a burden on both individuals and healthcare systems. T2D accounts for approximately 90% of all diabetes cases, making it a priority for improved prevention and management. T2D is associated with various pathological complications, including those affecting the neuromuscular system. Previous research suggests that individuals with T2D often exhibit slower walking speeds, altered gait patterns, decreased muscle strength and impaired mobility compared to non-diabetic individuals. The aim of this study was to examine how strength, balance, ankle range of motion and step length are associated with self-selected (SS) and maximum (MS) walking speeds among males with T2D. METHODS: The study design was cross-sectional, with 18 males (age 62.5 ± 10.6, body height 177.1 ± 5.4 cm, body weight 94.7 ± 16.7 kg), diagnosed with T2D. Participants were recruited from the Department of endocrinology at the University Hospital, Reykjavik, Iceland. Gait speed was assessed for both SS and MS. Maximum voluntary contraction (MVC) of plantar flexors was measured in a seated position using VALD ForceFrame and MVC of knee extensors with VALD Dynamo. Balance was evaluated during a 15 second single leg stance on VALD ForceDecks. Step length and ankle angles at heel strike and toe-off were determined using video recordings analyzed with the Dartfish software while walking on a treadmill. Jamovi software was used for statistical analysis. Pearsons´s correlation coefficient was used to assess the association between SS and MS with plantar flexor strength, knee extensor strength, single leg balance, step length and ankle angles at heel strike and toe-off. A significance level of α = 0.05 was set for all analyses. RESULTS: Among males with T2D, SS was strongly and significantly correlated with MS (r = 0.86, p < 0.001). Additionally, SS was significantly correlated with step length at SS (r = 0.69, p = 0.004) and the strength of plantar flexors (r = 0.63, p = 0.009). A moderate, but non-significant (p = 0.060) correlation was found between knee extensor strength and SS. No significant correlations were found between SS and single leg balance or ankle angles at heel strike and toe-off. For MS, significant positive correlations were found with plantar flexor strength (r = 0.662, p = 0.005), knee extensor strength (r = 0.579, p = 0.015), step length at MS (r = 0.562, p = 0.046) and ankle angle at toe- off (r = 0.612, p = 0.026). However, MS was not significantly correlated with single leg balance or ankle angle at heel strike. CONCLUSION: The results of this ongoing study indicate that among males with T2D, greater plantar flexor strength and step length are associated with faster SS and MS. Achieving higher MS may be further influenced by plantar flexion at toe-off and knee extensor strength. These findings suggest a possible beneficial effect of targeted strength training to improve walking speed in this population.
Read CV Birgitta Þóra BirgisdóttirECSS Paris 2023: OP-BM14