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Knee osteoarthritis (OA) is a public health problem affecting millions of people worldwide. The intensity of the tibiofemoral contact forces is related to cartilage degeneration, and so is the importance of quantifying joint loads during daily activities. Although simulation with musculoskeletal models has been used to calculate joint loads, it demands high-cost equipment and a very time-consuming process. This study aimed to evaluate consolidated machine learning algorithms to predict tibiofemoral forces during gait analysis of healthy individuals and knee OA patients. Also, we evaluated three different datasets to train each model, considering different combinations of primary kinematic and kinetic data, and post-processing data. We evaluated 14 patients with severe unilateral knee OA and 14 healthy individuals during 3-5 gait trials. Data were split into 70% and 30% of the samples as training and test data. Test data was independently evaluated considering a mixture of pathological and healthy individuals, and only OA and Control patients. The main results showed that accurate predictions of the tibiofemoral contact forces were achieved using machine learning methods and that the predictions were sensitive to changes in the input data as training. The present study provided insights into the most promising regressions methods to predict knee contact forces representing an important starting point for the broader application of biomechanical analysis in clinical environments.

Assuntos

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BACKGROUND: Maintenance of the medial longitudinal arch (MLA) of the foot is fundamental during functional tasks and disorders can lead to clinical alterations. Studies have demonstrated that deficits in ankle isokinetic performance can predispose an individual to lower limb injuries. OBJECTIVES: To evaluate the muscular performance of cavus, planus, and normal feet by means of torque/body mass and the isokinetic phases, to generate 3D surface map analysis, and to verify whether there is a relationship between MLA height and arch height flexibility with isokinetic performance. METHODS: The sample consisted of 105 healthy adult women, divided into three groups: normal, cavus, and planus. Assessment in concentric mode at 30, 60, and 90 °/s in the dorsiflexion and plantarflexion of the ankle joint were analyzed during the three isokinetic phases (acceleration, sustained velocity, and deceleration). The variables total range of motion, peak of torque (PT), and angle of PT were extracted within the sustained velocity. RESULTS: In dorsiflexion at 60 °/s, the phase where the velocicty is sustained (load range phase) was higher in the planus group (MeanDifference=10.9 %; ω2p = 0.06) when compared with the cavus group. Deficits in the peak torque/body mass in dorsiflexion at 60 °/s (cavus feet: MD=-3 N.m/kg; ω2p = 0.06; and planus feet: MD=-1.1 N.m/kg; ω2p = 0.06) were also observed as well as in the 3D surface maps, when compared with the normal group. The flexibility of MLA had a negative correlation of PT at 30 °/s in cavus group. The heigth of MLA had a postive correlation with the PT for the cavus and planus group ate 60 °/s. All other results did not show differences between the groups. CONCLUSIONS: The planus groups showed a better capacity of attain and sustained the velocity in dorsiflexion in relation the cavus group. The cavus and planus group had deficts in torque in relation the normal. The correlations were weak between the measures of MLA and PT. Thereby, in general the differences between foot types showed small effect in isokinetic muscle performance measures of the plantar and dorsi flexores. TRIAL REGISTRATION: Study design was approved by the IRB (#90238618.8.0000.5231).

Assuntos

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This study aimed to analyze the coordination and variability between the thorax, lumbar, and pelvis segments in runners with chronic low back pain group (LBPG) and matched control group (CG). Twenty-six recreational runners were evaluated on a treadmill at 3.3 m/s. The coordination of the pelvis-lumbar and lumbar-thorax in all three planes and between the transverse and frontal plane of the lumbar segment were evaluated using the vector coding technique. Coordination was analyzed via histograms with the percentage of each pattern and the coupling angle during the cycle. The variability coordination was calculated from the angular deviation between the cycles. Differences were observed in the coordination patterns and in the coupling angle during the cycle. Between the pelvis-lumbar in the frontal plane, the LBPG (x¯ = 50.6% (SD = 10.7)) presented more in-phase pattern than the CG (38.6% (8.7; P = 0.05). For the lumbar-thorax, differences occurred in all planes. Between the frontal-transverse plane of the lumbar segment, the LBPG (27.6% (7.9)) presented more in-phase pattern than the CG (38.6% (8.7); P = 0.02). The variability did not demonstrate the differences between the groups; these differences were observed in coordination between the lumbar and adjacent segments in all planes. The model of rigid segments and the coordination analyses were sensitive to detect these differences, and the presence of more in-phase patterns could be related to the protection mechanism in order to avoid painful movements.

Assuntos

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BACKGROUND: Many studies have investigated isokinetic performance in volleyball players but not through surface maps. OBJECTIVES: The goals of this study were to assess velocity-specific isokinetic knee extensor-flexor muscle strength and to compare the isokinetic knee extensor-flexor muscles between professional (PRO) and under-17 (U17) female volleyball players. METHOD: This cross-sectional laboratory study was developed with two groups: PRO (n = 12), medianage = 21.3 years, and U17 (n = 9), medianage = 15 years. Peak torque, total work, mean power, angle of peak torque, hamstring-quadriceps torque ratio (H-Q ratio) and torque-angle-velocity surface maps were analysed from knee extension-flexion at 60, 120 and 300 degrees per second (°/s). RESULTS: Significant differences were identified for extensor peak torque between PRO x = 202.3 Newton metre (N·m) (standard deviation [SD] = 24.4) and U17 x = 141.6 N·m (30.1) at 60 °/s (p < 0.001; d = 2.21) as well as flexor peak torque (PRO x = 75.7 N·m [10.3] and U17 x = 57.7 N·m [11.4]) at 120 °/s (p < 0.001; d = 1.65) for the dominant limb. There were also significant group differences for total work and mean power at all velocities for extension and flexion. Surface maps demonstrated higher torque at lower speeds for both groups with smaller torque changes across velocities for flexion. CONCLUSION: Different groups of female volleyball players showed contrasting concentric knee muscle strength across isokinetic velocities. CLINICAL IMPLICATIONS: These results demonstrate the importance of specific strength training for different age groups, even within the same sport, and provide insight into muscle strength.

RESUMO

BACKGROUND: and Purpose: Knee muscle strength deficits have been reported in individuals who have undergone anterior cruciate ligament reconstruction (ACLR). Isokinetic testing is a valid way to assess muscle strength. Some isokinetic variables, including the range of motion in the phases to attain a specific velocity, load range (sustained specific velocity), time to achieve deceleration, and qualitative analysis of the torque-angle velocity relationship, may contribute to understanding recovery of these individuals after surgery. Thus, the purpose of this study was to compare the load range (LR), time to attain velocity (TTAV), deceleration time (DT) phases, total range of motion (ROM), peak torque/body mass (PT/BM), angle of peak torque (AngPT) during LR and torque-angle-velocity relationships (TAV3D) between post ACLR and matched control subjects.Study design: Case-control. METHODS: Seven men who underwent ACLR and seven matched controls were evaluated from four to six months after surgery. Testing was performed on a Biodex System 4 isokinetic dynamometer in concentric mode at 60, 120 and 300 °/s, for knee flexion and extension. RESULTS: Statistically significant differences were seen for extension ROM at 60 °/s where ROM was greater in the control group. PT/BM for extensors was also significantly greater in controls by 20 % compared to ACLR at 60 and 120 °/s. PT/BM for flexors was significantly greater for controls at 60 °/s (∼15 %). TAV3D showed differences in torque and, specifically, the control group sustained knee flexion torque for a greater range of motion when compared to the ACLR group. CONCLUSION: The ACL group presented with lower ROM and PT/BM, therefore exhibiting worse muscle performance in comparison to the control group.Level of Evidence: 3.