Isokinetic trunk flexion-extension protocol to assess trunk muscle strength and endurance:Reliability,learning effect,and sex differences

Purpose:The purpose of this study was to examine the reliability and the learning effect of an isokinetic trunk flexion-extension protocol designed to simultaneously assess trunk muscle strength and endurance.In addition,the effect of the participants’sex on the reliability data was examined.Methods:Fifty-seven healthy and physically active young men(n=28)and women(n=29)performed the isokinetic protocol 5 times,separated by a week between each of the first 4 sessions and by a month between the last 2 sessions.The protocol consisted of performing 4 trials of 15 maximum flexion-extension concentric exertions at 120°/s(range of trunk motion=50°).The absolute and relative peak torque and total work were calculated to assess trunk flexion and extension strength.In addition,endurance ratio,modified endurance ratio,fatigue final ratio,recovery ratio,and modified recovery ratio variables were used for the assessment of trunk muscle endurance in both directions.Results:Regarding the absolute reliability,no relevant changes were found between paired-comparison sessions for most strength and endurance variables,except for total work and relative total work variables in the flexion movement in both sexes.In addition,the typical error of the isokinetic variables was lower than 10%in both males and females,and minimum detectable changes ranged from 7%to 20%,with a tendency to be higher in females and in endurance variables.The strength variables showed high-to-excellent intraclass correlation coefficients(ICCs;>0.74);however,for the endurance variables only the endurance ratio and the modified endurance ratio obtained moderate-to-high ICC values(0.57<ICC<0.82).In addition,the analysis of the variance reported no significant differences between consecutive pairs of sessions for most variables in both sexes.Conclusion:Overall,these findings provide clinicians,trainers,and researchers with a 10-min single-session protocol to perform a reliable muscle strength and endurance evaluation of trunk flexor and extensor muscles,all within the same protocol.

Timing and Classication of Patellofemoral Osteoarthritis Patients Using Fast Large Margin Classifier

:Surface electromyogram(sEMG)processing and classication can assist neurophysiological standardization and evaluation and provide habitational detection.The timing of muscle activation is critical in determining various medical conditions when looking at sEMG signals.Understanding muscle activation timing allows identication of muscle locations and feature validation for precise modeling.This work aims to develop a predictive model to investigate and interpret Patellofemoral(PF)osteoarthritis based on features extracted from the sEMG signal using pattern classication.To this end,sEMG signals were acquired from ve core muscles over about 200 reads from healthy adult patients while they were going upstairs.Onset,offset,and time duration for the Transversus Abdominus(TrA),Vastus Medialis Obliquus(VMO),Gluteus Medius(GM),Vastus Lateralis(VL),and Multidus Muscles(ML)were acquired to construct a classication model.The proposed classication model investigates function mapping from real-time space to a PF osteoarthritis discriminative feature space.The activation feature space of muscle timing is used to train several large margin classiers to modulate muscle activations and account for such activation measurements.The fast large margin classier achieved higher performance and faster convergence than support vector machines(SVMs)and other state-of-the-art classiers.The proposed sEMG classication framework achieved an average accuracy of 98.8%after 7 s training time,improving other classication techniques in previous literature.