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PubMed · 9236788

Decomposition-enhanced spike-triggered averaging: contraction level effects.

R A Conwit·B Tracy·C Jamison·M McHugh·D Stashuk·W F Brown·E J Metter
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Abstract

Decomposition-enhanced spike-triggered averaging (DE-STA) was applied to the vastus medialis muscle to examine size distributions of surface-detected motor-unit action potentials (S-MUAPs) at various force levels. Using DE-STA, 15-20 S-MUAPs were identified during 5%, 10%, 20%, and 30% of maximum voluntary contraction. Average S-MUAPs showed increase in peak to peak (and negative peak) amplitude with force (In microV): 5% = 37.9 +/- 6.1 (16.6 +/- 2.5), 10% = 44.0 +/- 4.0 (20.4 +/- 1.8), 20% = 80.7 +/- 9.3 (41.3 +/- 4.5), and 30% = 102.5 +/- 10.3 (53.6 +/- 5.0). Test-retest variability of peak to peak (and negative peak amplitude) between repeated trials was 0.10 (0.14), 0.14 (0.14), 0.17 (0.15), and 0.21 (0.20) at 5%, 10%, 20%, and 30% respectively. A relationship was found between the S-MUAP amplitude and force (r2 = 0.78, df = 90, F = 160, P < 0.001). Increase in average S-MUAP amplitude with force suggests that STA performed only at low levels of contraction may result in a biased sampling and small average S-MUAP amplitudes.

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Action PotentialsAdultAgedElectromyographyHumansMiddle AgedMuscle ContractionMuscle, SkeletalReproducibility of ResultsSample SizeJournal Article

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BibTeXRIS

R A Conwit, B Tracy, C Jamison, M McHugh, D Stashuk, W F Brown, E J Metter. 1997. Decomposition-enhanced spike-triggered averaging: contraction level effects.. https://doi.org/10.1002/(sici)1097-4598(199708)20%3A8%3C976%3A%3Aaid-mus7%3E3.0.co%3B2-3

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