Background: Excessive body weight is associated with gait alterations. In none of previous studies, body fat distribution has been considered as a factor that could change gait parameters and induce different neuromuscular adaptations. Objective: This multicenter, analytical, and cross-sectional study aimed to investigate the influence of the body mass distribution on gait parameters and ankle muscle coactivation in obese individuals. Methods: Three distinct groups were included in the study: a non-obese control group (CG, n = 15, average age = 32.8 ± 6.5 years, BMI = 21.4 ± 2.2 kg/m²), an obese-android group characterized by a Waist to Hip Ratio (WHR) greater than 1 (OAG, n = 15, age = 32.4 ± 3.9 years, BMI = 41.4 ± 3.9 kg/m², WHR = 1.2 ± 0.2), and an obese-gynoid group with a WHR less than 1 (OGG, n = 15, age = 35.4 ± 4.1 years, BMI = 40.0 ± 5.7 kg/m², WHR = 0.82 ± 0.3). All participants walked on an instrumented gait analysis treadmill at their self-selected walking speed for one minute. Spatiotemporal parameters, walking cycle phases, vertical ground reaction force (GRFv) and center of pressure (CoP) velocity were sampled from the treadmill software. Electromyography (EMG) activity of the gastrocnemius medialis (GM), the soleus (SOL) and tibialis anterior (TA) were collected during walking and used to calculate coactivation indexes (CI) between ankle plantar and dorsal flexors (GM/TA and SOL/TA) for the different walking cycle phases. Results: Compared to OAG, OGG walked with shorter and larger strides, lower CoP velocity and GRFv. During the single support phase, SOL/TA coactivation was higher in OAG compared to OGG (p < .05). During the propulsion phase, SOL/TA coactivation was higher in OGG compared to OAG (p < .05). Conclusion: Gait parameters and ankle muscle coactivation in obese individuals seem to be strongly dependent on body mass distribution. From the biomechanical point of view, body mass distribution changes gait strategies in obese individuals inducing different neuromuscular adaptations during the single support and propulsion phases.

The potential impact of a specific physical activity program on biomechanical gait parameters and neuromuscular strategies around the ankle joint in older adults with sarcopenic obesity (SO) remains largely unexplored. The objective of this study was to investigate the effectiveness of a 24-week Posture, Strengthening, and Motricity (PSM) program in improving neuromuscular strategies and biomechanical gait parameters in older adults with SO. 40 Participants were randomly assigned to either the trained group (TG) and the control group (CG). Only the TG received the PSM program. Standardized evaluations were performed before and after the intervention, including walking tests on an instrumented gait analysis treadmill to evaluate biomechanical gait parameters and EMG activity of ankle muscles. After the PSM program, TG exhibited an increase in comfortable walking speed (+80%, p<0.001) and step length (+38%, p<0.05). Moreover, TG demonstrated a reduction in CoP velocity (-26%, p<0.01). These gait modifications were associated with a decreased muscle activity during the different gait phases (p<0.05). The PSM program effectively improved gait, and neuromuscular capacities in older adults with SO. Notably, Results sheds light on the remarkable trainability of neuromuscular capacities in older adults with SO, despite the adverse effects of aging and obesity.

Background: The rate of force development (RFD) plays a pivotal role not only in preventing falls but also in ensuring successful completion of many functional tasks that demand swift muscle power rather than prolonged strength. Despite its importance, there is limited compre-hensive research on the relationship between RFD and walking speed, especially in older adults with Sarcopenic Obesity (SO). Objective: to investigate the influence of obesity on neuromuscular markers in older adults with SO and to assess the relationship between neuromuscular markers and gait speed in older adults with SO. Methods: a cohort of 42 participants was categorized based on their BMI into two groups: the sarcopenic non-obese group (CG, n=22; age=81.13±4.02; BMI=25.13±3.35) and the sarcopenic obese group (SOG, n=20; age=77.71±2.95; BMI=34.46±3.25). Gait speed was measured using a 10-meter test. Additionally, the isometric strength of the plantar flexor muscles was assessed during maximal voluntary contractions. Absolute Peak force (aPeak, N) were documented at intervals of 50 ms (a50, N), 100 ms (a100, N), and 200 ms (a200, N), subsequently normalized to body mass (r50, r100, r200, N). The RFD was derived in two phases: from the start of the contraction to 50 ms (RFD50-100) and from 100 to 200 ms (RFD100-200) and calculated from the linear slop of the force – time curve (Δ force/Δ time). Conclusion: Obesity negatively impacts neuromuscular markers in older adults. Notably, RFD emerges as the dominant factor influencing gait speed, accounting for an impressive 51% of its variability, far surpassing the impact of relative peak force. This underscores the imperative of evaluating neuromuscular health in older adults with SO to provide insights into mobility out-comes.