Table 1.
Percent changes of linear time–frequency parameters against percent changes of peak power output and signal-to-noise ratio.
| Muscle groups | Amplitude-based parameters | Spectral parameters | Instantaneous frequency | |||||
|---|---|---|---|---|---|---|---|---|
| RMS% | MAV% | MNF% | MDF% | IMNF% | IMDF% | |||
| PFs | MG | r (R2) | − 0.119**(1.42) | − 0.117**(1.37) | 0.078**(0.61) | 0.104**(1.08) | 0.121**(1.46) | 0.122**(1.49) |
| SNR | 6.264 | 6.781 | 6.359 | 6.362 | 7.453 | 7.926 | ||
| LG | r (R2) | − 0.094(0.88) | − 0.085*(0.72) | 0.148**(2.19) | 0.170**(2.89) | 0.176**(3.10) | 0.177**(3.13) | |
| SNR | 5.429 | 6.096 | 6.274 | 7.184 | 7.174 | 7.099 | ||
| KEs | VM | r (R2) | − 0.215**(4.62) | − 0.167**(2.79) | 0.093*(0.86) | 0.123**(1.51) | 0.227**(5.15) | 0.248**(6.15) |
| SNR | 7.763 | 7.418 | 5.671 | 5.235 | 7.715 | 8.301 | ||
| RF | r (R2) | − 0.159**(2.53) | − 0.117**(1.37) | 0.147**(2.16) | 0.233**(5.43) | 0.399**(15.92) | 0.443**(19.62) | |
| SNR | 7.334 | 7.208 | 7.878 | 7.724 | 8.136 | 8.341 | ||
| VL | r (R2) | − 0.160**(2.56) | − 0.135**(1.82) | 0.054(0.29) | 0.121**(1.46) | 0.300**(9.00) | 0.308**(9.49) | |
| SNR | 7.586 | 7.558 | 7.593 | 7.374 | 7.726 | 7.727 | ||
| HEs | GM | r (R2) | − 0.070(0.49) | − 0.069(0.48) | 0.088*(0.77) | 0.101*(1.02) | 0.130**(1.69) | 0.226**(5.11) |
| SNR | 4.438 | 4.438 | 4.096 | 3.991 | 4.811 | 4.974 | ||
| BF | r (R2) | − 0.101**(1.02) | − 0.077**(0.59) | 0.244**(5.95) | 0.301**(9.06) | 0.307**(9.42) | 0.361**(13.03) | |
| SNR | 4.784 | 4.773 | 3.971 | 5.012 | 4.843 | 5.115 | ||
PFs plantar flexors, KEs knee extensors, HEs hip extensors. MG medial gastrocnemius, LG lateral gastrocnemius, VM vastus medialis, RF rectus femoris, VL vastus lateralis, GM gluteus maximus, BF biceps femoris. r pearson's correlation coefficients, R2 coefficient of determination, SNR signal−to−noise ratio. RMS root mean square, MAV mean absolute value, MNF mean frequency, MDF median frequency, IMNF instantaneous mean frequency, IMDF instantaneous median frequency.
*P < 0.05, **P < 0.01, the correlations were significant.