Neuromuscular function of the quadriceps muscle during isometric maximal, submaximal and submaximal fatiguing voluntary contractions in knee osteoarthrosis patientsReport as inadecuate




Neuromuscular function of the quadriceps muscle during isometric maximal, submaximal and submaximal fatiguing voluntary contractions in knee osteoarthrosis patients - Download this document for free, or read online. Document in PDF available to download.

Introduction

Knee osteoarthrosis KOA is commonly associated with a dysfunction of the quadriceps muscle which contributes to alterations in motor performance. The underlying neuromuscular mechanisms of muscle dysfunction are not fully understood. The main objective of this study was to analyze how KOA affects neuromuscular function of the quadriceps muscle during different contraction intensities.

Materials and methods

The following parameters were assessed in 20 patients and 20 healthy controls: i joint position sense, i.e. position control mean absolute error, MAE at 30° and 50° of knee flexion, ii simple reaction time task performance, iii isometric maximal voluntary torque IMVT and root mean square of the EMG signal RMS-EMG, iv torque control, i.e. accuracy MAE, absolute fluctuation standard deviation, SD, relative fluctuation coefficient of variation, CV and periodicity mean frequency, MNF of the torque signal at 20%, 40% and 60% IMVT, v EMG-torque relationship at 20%, 40% and 60% IMVT and vi performance fatigability, i.e. time to task failure TTF at 40% IMVT.

Results

Compared to the control group, the KOA group displayed: i significantly higher MAE of the angle signal at 30° 99.3%; P = 0.027 and 50° 147.9%; P < 0.001, ii no significant differences in reaction time, iii significantly lower IMVT -41.6%; P = 0.001 and tendentially lower RMS-EMG of the rectus femoris -33.7%; P = 0.054, iv tendentially higher MAE of the torque signal at 20% IMVT 65.9%; P = 0.068, significantly lower SD of the torque signal at all three torque levels and greater MNF at 60% IMVT 44.8%; P = 0.018, v significantly increased RMS-EMG of the vastus lateralis at 20% 70.8%; P = 0.003 and 40% IMVT 33.3%; P = 0.034, significantly lower RMS-EMG of the biceps femoris at 20% -63.6%; P = 0.044 and 40% IMVT -41.3%; P = 0.028 and tendentially lower at 60% IMVT -24.3%; P = 0.075 and vi significantly shorter TTF -51.1%; P = 0.049.

Conclusion

KOA is not only associated with a deterioration of IMVT and neuromuscular activation, but also with an impaired position and torque control at submaximal torque levels, an altered EMG-torque relationship and a higher performance fatigability of the quadriceps muscle. It is recommended that the rehabilitation includes strengthening and fatiguing exercises at maximal and submaximal force levels.



Author: Anett Mau-Moeller , Robert Jacksteit, Mario Jackszis, Frank Feldhege, Matthias Weippert, Wolfram Mittelmeier, Rainer Bader, Ralf

Source: http://plos.srce.hr/



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