Table 3.
Accessory nerve stimulation and DQEMG of the ST muscle
| Parameter | Young | Old |
|---|---|---|
| Supramaximal stimulation, mA | 120 ± 31 | 114 ± 29 |
| CMAP –pk amplitude, mV | 12.6 ± 1.9 | 6.8 ± 1.3* |
| CMAP –pk area, mV·ms | 1,287.4 ± 552.7 | 589.5 ± 409.1* |
| Number of contractions | 8 ± 2 | 9 ± 1 |
| MUPTs/participant number | 25 ± 5 | 27 ± 6 |
| MUPTs/contraction | 3 ± 1 | 3 ± 1 |
| MUP pk-pk amplitude, µV | 702.1 ± 128.4 | 688.4 ± 160.9 |
| mSMUP –pk amplitude, µV | 71.1 ± 27.9 | 53.3 ± 16.4 |
| mSMUP –pk area, µV·ms | 427.7 ± 111.2 | 361.3 ± 104.9 |
| MUNE –pk area number | 228 ± 105 | 209 ± 89 |
Values are presented as the ensemble means ± SD; n = 20. Decomposition-based quantitative electromyography (DQEMG) of the superior trapezius (ST) muscle at 15% maximal voluntary isometric contraction (MVC). CMAP, compound mass action potential; –pk, negative peak; MUPT, motor unit potential trains; MUNE, motor unit number estimate; MUP, motor unit potential; pk-pk, peak to peak; mSMUP, mean surface motor unit potential.
*
P < 0.05.