Table 1.
Summary of conditions for, and experimental observations of, the subjects’ isometric muscle contractions
| PS | CS | P | |
|---|---|---|---|
| Subjects | 19 | 19 | |
| Age (years) | 55–80 | 49–78 | 0.110 |
| Mean (s.d.) | 69.5 (7.6) | 64.3 (8.1) | |
| Male:female | 11:8 | 12:7 | |
| No. of contractions | 46 | 32 | |
| No. of MUs | 50 | 39 | |
| ContrLev (%MVC) | |||
| Range | 2–40 | 2–45 | |
| Mean (s.d.) | 13.7 (8.7) | 12.3 (9.2) | 0.510 |
| FR (Hz) | |||
| Range | 5.0–19.5 | 6.0–17 | |
| Mean (s.d.) | 9.2 (3.1) | 10.3 (2.4) | 0.085 |
| MU/FCoh | |||
| Range | 0.08–0.91 | 0.08–0.87 | |
| Mean(s.d.) | 0.50 (0.25) | 0.36 (0.20) | 0.005* |
| TF (Hz) | |||
| Range | 4.5–8 | 6.0–9.0 | |
| Mean (s.d.) | 6.0 (1.1) | 7.0 (0.9) | <0.001* |
| eBW (Hz) | |||
| Range | 1.4–6.8 | 1.9–9.8 | |
| Mean (s.d.) | 3.6 (1.6) | 5.3 (1.7) | <0.001* |
| TreAmpl (%VC) | |||
| Range | 0.4–34.3 | 0.3–6.9 | |
| Mean (s.d.) | 10.2 (8.9) | 2.1 (1.5) | <0.001* |
The contraction level (ContrLev) is measured as a percentage of maximal voluntary contraction (%MVC); the MU firing rate (FR), the peak tremor frequency (TF) and the effective bandwidth (eBW) are given in Hz; and the tremor amplitude (TreAmpl) is measured as a percentage of the level of the voluntary contraction (%VC). For the number of segments used in our study, MU/force coherences (MU/FCoh) ≥ 0.08 are significant. The independent-samples t test was used for statistical evaluation; P values with asterisks indicate statistically significant differences. PS, parkinsonian subjects; CS, control subjects.