Abstract
Neuromuscular fatigue occurs as an effect of either peripheral and/or central mechanisms. In experimental exercise protocols fatigue has mainly been studied during isometric contraction setups or in pre/post fatigue protocol conditions the majority of which involved submaximal exercise modes. (reviewed by Cairns et al. 2005, and Knicker et al. 2011).
The purpose of the recent study was to reveal central and peripheral fatigue measures during long lasting submaximum concentric eccentric contraction conditions for m. quadriceps femoris in isokinetic mode. Peripheral and central fatigue effects could be
identified as a consequence of the underlying contraction protocol which caused severe declines of force output to be attributed to inhibition of MUAPs as the force decrease was accompanied by a pronounced downshift of the EMG median frequency due to i. deteriorated excitation-contraction coupling, ii. deminished motor neuron and/or muscle fibre excitability. The drop of the rate of MUAP and the related loss
of force output could not be compensated by enhanced recruitment of MUs. The time course of fatigue related parameters reveals reduced conduction velocity as the main contributor to force loss. An initially pronounced drop of force output may occur due to type II muscle fibre fatigue. Central fatigue could have developed in all structures above the neuromuscular interface and can have also involved motivational aspects.
The purpose of the recent study was to reveal central and peripheral fatigue measures during long lasting submaximum concentric eccentric contraction conditions for m. quadriceps femoris in isokinetic mode. Peripheral and central fatigue effects could be
identified as a consequence of the underlying contraction protocol which caused severe declines of force output to be attributed to inhibition of MUAPs as the force decrease was accompanied by a pronounced downshift of the EMG median frequency due to i. deteriorated excitation-contraction coupling, ii. deminished motor neuron and/or muscle fibre excitability. The drop of the rate of MUAP and the related loss
of force output could not be compensated by enhanced recruitment of MUs. The time course of fatigue related parameters reveals reduced conduction velocity as the main contributor to force loss. An initially pronounced drop of force output may occur due to type II muscle fibre fatigue. Central fatigue could have developed in all structures above the neuromuscular interface and can have also involved motivational aspects.
Original language | English |
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Title of host publication | Proceedings of the 9th IACSS Symposium 2013, Istanbul |
Publication date | 20.06.2013 |
Publication status | Published - 20.06.2013 |
Event | Symposium of the IACSS - Istanbul, Turkey Duration: 19.06.2013 → 22.06.2013 Conference number: 9 |