Table 2.
Baseline muscle force, tetanic properties, and f50
| Young | Older | 95% CI | P | |
|---|---|---|---|---|
| Baseline MVC, N | 380 ± 66 | 317 ± 75 | −137, −10 | 0.087 |
| Tetanic force, N | 281 ± 62 | 211 ± 39 | −127, −12 | 0.020 |
| Max RFD, % peak force·ms−1 | 0.54 ± 0.07 | 0.50 ± 0.11 | −0.14, 0.06 | 0.392 |
| Max RFR, % peak force·ms−1 | 1.31 ± 0.19 | 0.93 ± 0.20 | 0.17, 0.60 | 0.002 |
| Half-relax time, ms | 106 ± 5 | 149 ± 15 | 30, 55 | <0.001 |
| f50, Hz | 14.8 ± 2.1 | 10.9 ± 2.0 | −6.2, −1.7 | 0.002 |
Values are mean ± SD. 95% confidence intervals for the difference between groups are presented for each variable. MVC, maximal voluntary isometric contraction (n = 9 young and 9 older); Tetanic force from 75 Hz stimulation (n = 7 young and 8 older); contractile properties from the 50 Hz tetanus (n = 8 young and 8 older), including max RFD, maximum rate of force development; max RFR, maximum rate of force relaxation; half-relax time; f50, frequency calculated to produce 50% of maximal tetanic force (n = 7 young and 8 older).