Table 3.
Motor evoked potentials (MEPs) during scaled voluntary muscle activation.
| A. Response in muscle group of interest (PFM) | SMA | M1-L | ||
| PFM MEP (% max) | Vol. PFM | Vol. GMM | Vol. PFM | Vol. GMM |
|
Population Mean Slope
[%-PFM-MAX-MEP per %-PFM-MVC] |
0.5048 | 0.3951 | 0.5324 | 0.3864 |
| standard error (SE) | 0.0574 | 0.1003 | 0.0992 | 0.0662 |
| p-value | p = 0.0001 | p = 0.0076 | p = 0.0017 | p = 0.0011 |
| 95% confidence interval | 0.3642, 0.6453 | 0.1497, 0.6405 | 0.2897, 0.7751 | 0.2244 to 0.5484 |
|
Population Mean Intercept
[%-PFM-MAX-MEP] |
30.1635 | 35.7143 | 25.5859 | 28.0732 |
| standard error (SE) | 2.4474 | 4.8129 | 5.5339 | 3.1934 |
| p-value | p < 0.0001 | p = 0.0003 | p = 0.0036 | p = 0.0001 |
| 95% confidence interval | 24.1750, 36.1521 | 23.9377, 47.4910 | 12.0451, 39.1268 | 20.2591, 35.8873 |
| B. Response in muscle group of interest (GMM) | SMA | M1-L | ||
| GMM MEP (% max) | Vol. PFM | Vol. GMM | Vol. PFM | Vol. GMM |
|
Population Mean Slope
[%-GMM-MAX-MEP per %-GMM-MVC] |
−0.0230 | 0.6835 | 0.2369 | 0.5534 |
| standard error (SE) | 0.0484 | 0.1599 | 0.0572 | 0.1458 |
| p-value | p = 0.6506 | p = 0.0052 | p = 0.0061 | p = 0.0090 |
| 95% confidence interval | −0.1413, 0.0953 | 0.2924, 1.0747 | 0.0970, 0.3768 | 0.1966, 0.9101 |
|
Population Mean Intercept
[%-GMM-MAX-MEP] |
4.7665 | 34.5084 | 4.3409 | 39.9516 |
| standard error (SE) | 2.1595 | 8.2745 | 1.5374 | 4.3683 |
| p-value | p = 0.0694 | p = 0.0059 | p = 0.0302 | p < 0.0001 |
| 95% confidence interval | −0.5175, 10.0505 | 14.2615, 54.7553 | 0.5791, 8.1028 | 29.2628, 50.6405 |
| C. Onset of MEP during GMM scaled voluntary activation | SMA | M1-L | ||
| MEP in PFM | MEP in GMM | MEP in PFM | MEP in GMM | |
|
Population Mean Slope
[ms per %-GMM-MVC] |
0.0284 | 0.0240 | 0.0021 | 0.0144 |
| standard error (SE) | 0.0177 | 0.0156 | 0.0174 | 0.0135 |
| p-value | p = 0.1585 | p = 0.1754 | p = 0.9090 | p = 0.3275 |
| 95% confidence interval | −0.0148, 0.0716 | −0.0142, 0.0622 | −0.0406, 0.0447 | −0.0187, 0.0475 |
|
Population Mean Intercept
[ms: milliseconds] |
21.3103 | 18.3875 | 21.4185 | 18.7656 |
| standard error (SE) | 0.8234 | 1.3216 | 0.6752 | 0.6972 |
| p-value | p < 0.0001 | p < 0.0001 | p < 0.0001 | p < 0.0001 |
| 95% confidence interval | 19.2956, 23.3249 | 15.1536, 21.6213 | 19.7663, 23.0708 | 17.0597, 20.4715 |
Activating the isolated-pelvic coordination pattern, scaling PFM voluntary activation (columns 2 & 4) was not associated with induction of MEPs in the GMM, as expected from the EMG study results. Maximum co-activation of GMM [%-GMM-MVC] was small: 4.6501 while stimulating SMA and 3.9290 while stimulating M1-L.
The onset difference was significant, the onset of MEPs induced in the PFM happened after the onset of the MEPs induced in the GMM, regardless of the activation level of the GMM. While stimulating SMA, estimated intercept difference [onset of PFM MEP - onset of GMM MEP] = 2.7468 ms, SE = 0.7532, p = 0.0003, 95%CI (4.2259, 1.2678). While stimulating M1-L, estimated intercept difference [onset of PFM MEP - onset of GMM MEP] = 2.5997 ms, SE = 0.7994, p = 0.0012, 95%CI (4.1694, 1.0301).
Each PFM hotspot, SMA and M1-L, was stimulated under different levels of voluntary pre-activation.
Statistics are based on linear mixed effects regression models; see METHODS section.
PFM (pelvic floor muscles); GMM (gluteus maximus muscle).
Vol. PFM: Scaling PFM voluntary activation.
Vol. GMM: Scaling GMM voluntary activation.