Table 2. Properties of the force-frequency relationship in studied motor units in control and trained animals.
| C | 2W | 4W | 8W | |
|---|---|---|---|---|
| FF | ||||
| 60%Fmax [Hz] | 27.70 ± 6.37 | 29.81 ± 8.29 | 29.49 ± 9.84 | 29.05 ± 7.95 |
| Slope [%Fmax 1Hz-1] | 1.89 ± 0.46 | 1.84 ± 0.50 | 2.13 ± 0.79 | 2.05 ± 0.69 |
| FR | ||||
| 60%Fmax [Hz] | 29.32 ± 4.62 | 35.29 ± 5.10 *** | 35.49 ± 6.10 *** | 38.21 ± 5.43 ***† |
| Slope [%Fmax 1Hz-1] | 2.73 ± 0.70 | 2.71 ± 0.61 | 2.79 ± 0.65 | 2.99 ± 0.66 |
| S | ||||
| 60%Fmax [Hz] | 18.83 ± 2.05 | 21.12 ± 5.63 | 18.54 ± 4.96 | 20.65 ± 3.16 § |
| Slope [%Fmax 1Hz-1] | 5.35 ± 1.97 | 4.63 ± 2.50 | 6.87 ± 2.14 †† | 4.98 ± 1.99 § |
Values of parameters describing the force-frequency relationships (mean values ± SD) of the three basic types of motor units, fast fatigable (FF), fast fatigue resistant (FR) and slow (S), for the control (C) group and the three trained groups, consisting of rats trained for 2 weeks (2W), 4 weeks (4W) and 8 weeks (8W).
60%Fmax, the stimulation frequency necessary to reach 60% of the maximum force; slope, the slope of a steep part of the curve at approximately 60% of the maximum force.
Statistical significance relative to the control group is represented by *** p < 0.001.
Statistical significance relative to the group trained for 2 weeks (2W) is represented by † p < 0.05, †† p < 0.01.
Statistical significance in comparison to the group trained for 4 weeks (4W) is represented by § p < 0.05 (Dunn’s post hoc test) (S7 File).