Table 1 Accelerometer variables

Time

Isolated non-paretic limb activity [31]

Time, in hours, that the non-paretic limb is moving, while the paretic limb is still

Isolated paretic limb activity [31]

Time, in hours, that the paretic limb is moving, while the non-paretic limb is still

Bilateral activity [13, 31]

Time, in hours, that both upper limbs are moving together

Use ratio [16, 28, 47]

Ratio of hours of paretic limb movement, relative to hours of non-paretic limb movement

Magnitude

Paretic limb magnitude [48, 49]

Magnitude of accelerations of the paretic limb, in activity counts*

Bilateral magnitude [13, 31]

Intensity, or magnitude of accelerations, of movement across both arms, in activity counts*

Magnitude ratio [13, 31, 49]

Ratio of the magnitude of paretic UL accelerations relative to the magnitude of the non-paretic UL accelerations. This ratio reflects the contribution of each limb to activity, expressed as a natural log

Variability

Variability of paretic movement [48, 49]

Standard deviation of the magnitude of accelerations across the paretic limb, reflecting the variability of paretic limb movement, in activity counts*

Variability of bilateral movement [48, 49]

Standard deviation of the magnitude of accelerations across both limbs, reflecting the variability of bilateral upper limb movement, in activity counts*

Variation ratio [48, 49]

Ratio of the variability of paretic limb accelerations relative to the variability of the non-paretic limb accelerations, reflecting the relative variability in the paretic limb

Smoothness

Unimanual Jerk Asymmetry Index [34]

Ratio of the average jerk magnitude between the paretic upper limb and the nonparetic upper limb. Higher jerk represents less smooth movement, and an index value of 0 represents similar smoothness of movement in the paretic and non-paretic limbs. Values are bounded between − 1 to + 1

Spectral arc length [35, 36]

A measure of movement smoothness that quantifies movement intermittencies independent of the movement’s amplitude and duration. Longer spectral arc lengths are reflective of less smooth or less coordinated movement