Decomposition-enhanced spike-triggered averaging: Contraction level effects

✍ Scribed by Robin A. Conwit; Brian Tracy; Chris Jamison; Megan Mchugh; Dan Stashuk; William F. Brown; E. Jeffrey Metter

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 249 KB
• Volume: 20
• Category: Article
• ISSN: 0148-639X
• DOI: 10.1002/(sici)1097-4598(199708)20:8<976::aid-mus7>3.0.co;2-3

✦ Synopsis

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 µV): 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 (r 2 = 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.