Origins of Balance Disorders during a Daily Living Movement in Obese: Can Biomechanical Factors Explain Everything?

Abstract

Obese people suffer from postural deficits and are more subject to falls than their lean counterpart. To improve prevention and post-fall rehabilitation programs, it seems important to better understand the posturo-kinetic disorders in daily life situations by determining the contribution of some key factors, mainly morphological characteristics and physical activity level, in the apparition of these disorders.Twelve severe android obese and eight healthy non obese adults performed a reaching task mobilizing the whole body. To further determine the origin of the postural and motor behavior differences, non obese individuals also performed an experimental session with additional constraints which simulated some of the obese morphological characteristics. Impact of the sedentary lifestyle was also studied by dissociation of the obese in two subgroups: physically « active » and physically « inactive ». Movement kinetics and kinematics were characterized with an optoelectronic system synchronized to a force platform. The mechanical equilibrium pattern was evaluated through the displacements of the Centre of Mass (CoM) and the centre of foot pressure within the Base of Support (BoS).Results showed that obesity decreased movement speed (≈−23%, p<0.01), strongly increased CoM displacement (≈+30%, p<0.05) and induced an important spatio-temporal desynchronization (≈+40%, p<0.05) of the focal and postural components of the movement during the transition between the descending and ascending movements.The role of some morphological characteristics and of physical activity on obese patients' postural control disorder is discussed and set back in the more general context of overall factors contributing to postural deficits with obesity.

Influencia do indice de massa corporal no equilibrio e na configuracao plantar em obesos adultos

“…Observaram que indivíduos com IMC acima de 30 Kg/m² apresentaram redução no tempo de manutenção quando comparados com não obesos 12,13 . Outros estudos demonstraram atraso de 20 a 40% do impulso motor e sensorial sobre o nervo mediano, ulnar, fibular e tibial, quando comparado com sujeitos não obesos sugerindo redução do recrutamento de unidades motoras e da força muscular 14 . Pesquisas referem à influência do IMC no equilíbrio postural estático e dinâmico em indivíduos idosos.…”

“…Por meio do mecanismo sensorial, os mecanorreceptores ativos durante a absorção do impacto dos pés no solo influenciam nos segmentos adjacentes 21 . As alterações posturais acontecem em conjunto, por exemplo, quando um pé pronado toca o solo, provavelmente será observada rotação interna da tíbia, joelho valgo, rotação medial do fêmur e queda da pelve contralateral 14 . Essas alterações podem ter origem ascendente ou descendente, levando a adequação postural de toda a cadeia cinética do membro inferior.…”

Beware of Ultra-Low-Velocity Knee Dislocation

“…There is also a large body of evidence suggesting that obese patients have displaced centers of mass and altered gait kinematics and are at increased risk of falls. 15,16 In a morbidly obese patient with a generous soft tissue envelope, deformity of the femur and tibia at the knee can be difficult to assess clinically. This can result in dulled suspicion at the time of index evaluation and a delay to radiography.…”

Sensory Integration and Response to Balance Perturbation in Overweight Physically Active Individuals

“…A recent study found that movement speed during a motor control behavior task is slower in inactive obese individuals compared with active ones (Mignardot, Olivier, Promayon, & Nougier, 2013). The fact that overweight participants were physically active in our study might have enhanced their muscle function and strength, and consequently their response strength, enabling them to maintain a similar latency response to unexpected external perturbation.…”