ABSTRACT
This study investigated the effects of a foot core intervention on the coordination of foot joints in recreational runners. This was a secondary analysis from a randomized controlled trial conducted with 87 recreational runners allocated to the control group (CG), which followed a placebo lower limb stretching protocol, or the intervention group (IG), which underwent an 8-week (3 times/week) foot core training. The participants ran on a force-instrumented treadmill at a self-selected speed (9.5-10.5 km/h) while the foot segment motion was captured. The vector coding technique was used to assess inter-joint coordination for four selected coupled segment and joint angles. The coordination patterns of the calcaneus and midfoot (CalMid) and midfoot and metatarsus (MidMet) joint pairs were affected. In the frontal plane, IG showed an in-phase with proximal dominancy coordination at heel strike, with a decrease in its frequency after the training (P=0.018), suggesting a longer foot supination. Additionally, IG showed an anti-phase with distal dominancy pattern at early stance compared to CG due to a smaller but earlier inversion of the CalMid-MidMet pair (P=0.020). The intervention also had an effect on the transverse plane of the CalMid-MidMet pair, with IG showing a significantly greater frequency of anti-phase coordination with proximal dominancy during propulsion than CG (P=0.013), probably due to a reduction in the CalMid abduction. Overall, the results suggested that the foot core intervention reduces the occurrence of running-related injuries by increasing the resistance to calcaneus pronation and building a more rigid and efficient lever during push-off.
ABSTRACT
Lower limb ankle exoskeletons have been used to improve walking efficiency and assist the elderly and patients with motor dysfunction in daily activities or rehabilitation training, while the assistance patterns may influence the wearer's lower limb muscle activities and coordination patterns. In this paper, we aim to evaluate the effects of different ankle exoskeleton assistance patterns on wearer's lower limb muscle activities and coordination patterns. A tethered ankle exoskeleton with nine assistance patterns that combined with differenet actuation timing values and torque magnitude levels was used to assist human walking. Lower limb muscle surface electromyography signals were collected from 7 participants walking on a treadmill at a speed of 1.25 m/s. Results showed that the soleus muscle activities were significantly reduced during assisted walking. In one assistance pattern with peak time in 49% of stride and peak torque at 0.7 N·m/kg, the soleus muscle activity was decreased by (38.5 ± 10.8)%. Compared with actuation timing, the assistance torque magnitude had a more significant influence on soleus muscle activity. In all assistance patterns, the eight lower limb muscle activities could be decomposed to five basic muscle synergies. The muscle synergies changed little under assistance with appropriate actuation timing and torque magnitude. Besides, co-contraction indexs of soleus and tibialis anterior, rectus femoris and semitendinosus under exoskeleton assistance were higher than normal walking. Our results are expected to help to understand how healthy wearers adjust their neuromuscular control mechanisms to adapt to different exoskeleton assistance patterns, and provide reference to select appropriate assistance to improve walking efficiency.
Subject(s)
Aged , Humans , Ankle/physiology , Ankle Joint/physiology , Biomechanical Phenomena/physiology , Electromyography , Exoskeleton Device , Gait/physiology , Muscle Contraction , Muscle, Skeletal/physiology , Walking/physiologyABSTRACT
El estudio del ajuste conductual a entornos donde las interacciones entre los individuos y sus consecuencias son interdependientes ha derivado en procedimientos que limitan la interacción y restringen la operante a la simple simultaneidad de acciones sobre operandos individuales. En este estudio se evaluó una metodología alterna, en la que se expuso a pares de ratas a ir de un lugar a otro. El acceso al alimento fue contingente al trabajo individual o conjunto, en función de las posibilidades de interacción directa, determinadas por la ubicación de los sujetos. Se identificó coordinación únicamente en las diadas expuestas a interacción directa. El protocolo propuesto permite estudiar el ajuste a pagos interdependientes producto de patrones de acción conjunta.
The study of behavioral adjustment to environments in which interactions among individuals and their consequences are interdependent has resulted in procedures that limit interaction and restrict the operant to the simple simultaneity of actions on individuals' operands. This study evaluated an alternative methodology in which pairs of rats were made to go from one place to another. Access to food was contingent upon individual or joint work, depending on the possibilities of direct interaction determined by the location of the subjects. Coordination was identified only in the pairs that had direct interaction. The suggested protocol makes it possible to study the adjustment to interdependent payoffs resulting from joint action patterns.
O estudo do ajuste de conduta a ambientes nos quais as interações entre os indivíduos e suas consequências são interdependentes deriva em procedimentos que limitam a interação e restringem a operante à simples simultaneidade de ações sobre operandos individuais. Neste estudo, avaliou-se uma metodologia alterna, na qual se expôs a pares de ratos a ir de um lugar a outro. O acesso ao alimento foi contingente ao trabalho individual ou conjunto, em função das possibilidades de interação direta, determinadas pela localização dos sujeitos. Identificou-se coordenação unicamente nas díades expostas à interação direta. O protocolo proposto permite estudar o ajuste a pagamentos interdependentes produto de padrões de ação conjunta.