Table 1.
Upper limb performance variables.
| Upper limb performance variable name | Description | Data source | Included in final solution |
|---|---|---|---|
| Duration | |||
| Hours of paretic/non-dominant limb activity (7, 8) | Time, in hours, that the paretic/non-dominant limb is moving. | 1 Hz | ✓ |
| Hours of non-paretic/dominant limb activity (7, 8) | Time, in hours, that the non-paretic/dominant limb is moving. | 1 Hz | ✓ |
| Isolated paretic/non-dominant limb activity (8) | Time, in hours, that the paretic/non-dominant limb is moving, while the non-paretic/dominant limb is still. | 1 Hz | |
| Isolated non-paretic/dominant limb activity (8) | Time in hours that the non-paretic/dominant limb is moving, while the paretic/non-dominant limb is still. | 1 Hz | |
| Magnitude | |||
| Median acceleration of paretic/non-dominant limb*(3, 8, 21) | Magnitude of accelerations of the paretic/non-dominant limb, in activity counts or gravitational units. | 1 Hz | ✓ |
| Bilateral magnitude*(3, 8, 21) | Intensity, or magnitude of accelerations of movement across both arms, in activity counts. | 1 Hz | |
| Variability | |||
| Acceleration variability of paretic/non-dominant limb activity*(12, 23) | Standard deviation of the magnitude of accelerations across the paretic/non-dominant limb, reflecting the variability of paretic/non-dominant limb movement, in activity counts. | 1 Hz | ✓ |
| Symmetry | |||
| Use ratio† (7, 9, 40) | Ratio of hours of paretic/non-dominant limb movement, relative to hours of non-paretic/dominant limb movement. | 1 Hz | ✓ |
| Magnitude ratio† (8, 12, 23) | Ratio of the magnitude of paretic/non-dominant UL accelerations relative to the magnitude of the non-paretic/dominant UL accelerations. This ratio reflects the contribution of each limb to activity, expressed as a natural log. | 1 Hz | |
| Quality of movement | |||
| Jerk asymmetry index (26) | Ratio of the average jerk magnitude between the paretic/non-dominant limb and the non-paretic/dominant limb. Higher jerk represents less smooth movement, and an index of 0 represents similar smoothness of movement in the paretic/non-dominant and non-paretic/dominant limbs. Values are bounded between −1 and +1. | 30 Hz | |
| Spectral arc length of paretic/non-dominant and non-paretic/dominant limb (6, 24, 25) | A measure of movement smoothness that quantifies movement intermittencies independent of the movement's amplitude and duration. | 30 Hz | |
| Longer spectral arc lengths are reflective of less smooth or less coordinated movement in either the paretic/non-dominant or non-paretic/dominant limb respectively | 30 Hz |
*
Variables that are quantified in activity counts, computed by the Actilife proprietary software such that 1 activity count = 0.001664 g.
†
For persons with stroke, ratios are paretic to non-paretic, while for neurologically-intact adults, ratios are non-dominant to dominant.