ABSTRACT
Objective To develop plantar force model of patellofemoral pain (PFP), so as to provide theoretical references for the assessment of PFP rehabilitation. Methods The case-control study was conducted, and a total of 126 patients with PFP and 126 healthy controls matched by gender and age were enrolled in the study. The participants were tested for plantar force and pressure during level walking, and twelve plantar regions were divided and recorded. Whether the participants suffered PFP was analyzed as dependent variable, meanwhile the peak force and peak pressure in 12 plantar regions of participants at selected speed during level walking were analyzed as independent variables. Conditional logistic regression (CLR) equations of peak force and peak pressure with PFP were established, respectively. The receiver-operating characteristic (ROC) curve of the corresponding equations was derived, and the area under ROC curve was calculated to analyzed the validity of different equations on PFP assessment. Results The CLC equation of peak force in 12 plantar regions of the participants with FFP was constructed, and only peak force of lateral heel was in the equation. The CLC equation of peak pressure in each plantar region included medial heel, midfoot, 1st and 2nd metatarsals. Meanwhile, the area under ROC curve of the pressure equation was larger than that of the force equation. Conclusions Peak force and pressure at different plantar regions can be used to assess PFP during level walking, and peak pressure is more effective for assessment.
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Objective To investigate the plantar force characteristics during human walking and running under different gravity environment. Methods Seven healthy male volunteers walked and ran in vertical position on a weight-loss suspension treadmill under simulated Mars gravity (1/3 G) and lunar gravity (1/6 G), and traditional earth gravity (1 G) respectively at three different velocities (3, 7 and 10 km/h). During the exercise, parameters such as stance phase, plantar force, and gait balance in gait cycle were analyzed by using the F-scan insole pressure distribution measurement system. Results At the same velocity during a gait cycle, the contact phase was significantly shorter with the decrease of gravity, but the swing phase was significantly longer (P0.05). The peak and average plantar force, force integrity were significantly reduced with the decrease of gravity. Under normal gravity, the increase of velocity could lead to an obvious increase in peak and average plantar force and an obvious decrease in force integrity. While under simulated lunar and Mars gravity, no significant changes were found in plantar force (P>0.05). Under the three gravities, the ratio of vertical impact was quite different in between (P<0.05), but no significant difference was found in the phase symmetry index. Conclusions As compared to normal gravity environment, parameters benefiting for skeleton and muscle function such as plantar force and contact phase were found to be much smaller under low gravity environment, indicating the necessity of considering these factors when designing countermeasures or exercise prescriptions for space flight so as to sustain the astronaut’s normal function of skeleton and muscle.
ABSTRACT
Objective To study dynamic characteristics of the ankle gait simulator, simulate plantar forces in the vertical, anterior-posterior, right-left direction during the stance phase, and validate such forces in the experimental setup. Methods The Adams virtual prototype and ankle model (including tendons, ligaments and soft tissues of foot) were established for dynamic simulation based on the self-developed 5 DOF gait simulator. The dynamic results from both the prototype and gait simulator were compared with the real plantar forces. Results The simulated plantar force could accurately fit the normal in vivo ankle position curves during a stance phase in three directions, and the tendons, ligaments and soft tissues had important influences on the correct gait. The simulated plantar force by the gait simulator could be repeatedly fit for the real stance plantar force. Conclusions The gait simulator was proved to simulate the human gait stance well and can provide a clinical research platform for those experiments which are incapable of in vivo measurement.
ABSTRACT
OBJETIVO: Investigou-se a influência da carga e posicionamento do material escolar sobre a distribuição da força plantar (DFP) e trajetória do centro de pressão (COP) em estudantes. MÉTODOS: Participaram 30 voluntários (10,7 ± 1,35 anos), ambos os gêneros, sem alteração postural. Dados baropodométricos foram coletados em sistema de baropodometria computadorizada (Matscan Research, Teckscanâ, 5.72): sem carga (controle); com carga (mochila) de 5, 10 e 15 por cento da massa corporal, posicionada nas regiões anterior e posterior do tronco, ombro direito e esquerdo. RESULTADOS: Sem carga, a DFP foi maior no calcâneo esquerdo comparado ao direito (p< 0,05). Com carga de 10 por cento no ombro esquerdo, a DFP foi maior à direita e menor à esquerda, comparado ao controle (p< 0,05). Com 5 por cento na região posterior do tronco, a DFP foi menor no médio-pé direito (mpD) e antepé esquerdo (apE); com 10 por cento, foi menor no mpD e mpE e maior no artelho direito (atD); com 15 por cento, foi menor no mpD e maior no atD (p< 0,05). A força plantar foi maior no atD com carga de 10 e 15 por cento em relação a 5 por cento (p< 0,05). Com carga de 15 por cento nas regiões anterior e posterior do tronco, a trajetória do COP foi maior (p< 0,05) comparada à carga de 5 por cento. A DFP não foi influenciada pelas diferentes cargas e posições da mochila. CONCLUSÕES: Considerando o aumento da trajetória do COP com carga de 15 por cento, recomenda-se que a carga das mochilas escolares não ultrapasse 10 por cento da massa corporal. Sugere-se investigação das adaptações da postura às diferentes cargas e posições da mochila, visando detectar possíveis alterações e propor ações preventivas.
OBJECTIVE: The influence of the weight and positioning of school supplies and books in backpacks, on plantar force distribution (PFD) and pressure center location, was investigated among students. METHODS: Thirty volunteers of both genders participated in the study. Their mean age was 10.76 (± 1.35) years and none of them had postural abnormalities. Baropodometric data were collected using a computerized baropodometric system (Matscan Research, Tekscanâ, 5.72): without load (control) and with loads of 5, 10 and 15 percent of body weight in a backpack, positioned on the back, on the chest and on the right and left shoulders. RESULTS: The PFD without load was greater on the left heel than on the right heel (p< 0.05). With a load of 10 percent on the left shoulder, the PFD was greater on the right and smaller on the left foot, in comparison with the control (p< 0.05). With a load of 5 percent on the back, the PFD was smaller on the right midfoot (RMF) and left forefoot (lff); with 10 percent, it was smaller on the RMF and left midfoot (LMF) and greater on the right toes (RT); with 15 percent, it was smaller on the RMF and greater on the RT (p< 0.05). The plantar force was greater on the RT with loads of 10 percent and 15 percent than it was with loads of 5 percent (p< 0.05). With loads of 15 percent on the back and on the chest, the pressure center displacement was greater than with a load of 5 percent (p< 0.05). The PFD was not influenced by the different loads and backpack positions. CONCLUSIONS: Taking into consideration the increased pressure center displacement with a load of 15 percent, it is recommended that school backpack loads should not exceed 10 percent of body mass. Investigations on posture adaptations to different loads and backpack positions are suggested, in order to detect possible abnormalities and propose preventive actions.