Abstract
OBJECTIVE: To assess the intra- and inter-session reliability of estimates of motor unit behavior and muscle fiber properties derived from high-density surface electromyography (HDEMG).
METHODS: Ten healthy subjects performed submaximal isometric knee extensions during three recording sessions (separate days) at 10%, 30%, 50% and 70% of their maximum voluntary effort. The discharge timings of motor units of the vastus lateralis and medialis muscles were automatically identified from HDEMG by a decomposition algorithm. We characterized the number of detected motor units, their discharge rates, the coefficient of variation of their inter-spike intervals (CoVisi), the action potential conduction velocity and peak-to-peak amplitude. Reliability was assessed for each motor unit characteristics by intra-class correlation coefficient (ICC). Additionally, a pulse-to-noise ratio (PNR) was calculated, to verify the accuracy of the decomposition.
RESULTS: Good to excellent reliability within and between sessions was found for all motor unit characteristics at all force levels (ICCs>0.8), with the exception of CoVisi that presented poor reliability (ICC<0.6). PNR was high and similar for both muscles with values ranging between 45.1 and 47.6dB (accuracy>95%).
CONCLUSION: Motor unit features can be assessed non-invasively and reliably within and across sessions over a wide range of force levels.
SIGNIFICANCE: These results suggest that it is possible to characterize motor units in longitudinal intervention studies.
Original language | English |
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Pages (from-to) | 2534-2541 |
Number of pages | 8 |
Journal | Clinical Neurophysiology |
Volume | 127 |
Issue number | 6 |
Early online date | 23 Dec 2015 |
DOIs | |
Publication status | Published - Jun 2016 |
Keywords
- High-density surface EMG
- Motor unit decomposition
- Conduction velocity
- Motor unit discharge rate
- Vastus lateralis
- Vastus medialis