From: A unified scheme for the benchmarking of upper limb functions in neurological disorders
Motor Ability | Performance Indicator | Domain | Mandatory/Recommended | Description | Relevant reference | |
---|---|---|---|---|---|---|
Kin | EMG | |||||
Accuracy | Trajectory absolute error | x | R | Mean or maximal distance between ideal and actual trajectory between movement onset and end | [57] | |
End-point error | x | R | Mean or maximal Euclidean distance between actual and target position at or after movement end | [58] | ||
Variable error | x | R | Standard deviation of the end-point error across multiple repetitions of the movement or task | [59] | ||
Area Index | x | R | Area between the desired straight line and the path actually performed | [60] | ||
Efficacy | Success rate | x | R | Number of accomplished objectives (e.g., movements performed, tasks completed) divided by the total number of attempts | [61] | |
Number of movements stops | x | M | Number of times that the velocity curve dropped below a percentage of peak velocity after movement onset | [62] | ||
Efficiency | Movement time | x | R | Time from the onset to the end of a task or movement | [63] | |
Path traveled | x | R | Path length covered between onset and end of a movement or task | [64] | ||
Path length ratio | x | M | Ratio between the path traveled and the shortest possible distance between movement onset and end | [65] | ||
Trunk compensation | x | R | Ratio between trunk displacement and hand displacement in the sagittal plane | [66] | ||
Waveform length | x | R | Cumulative length of the waveform of the EMG signal from the ith-muscle over the time segment | [67] | ||
Average amplitude change | x | R | Mean of the cumulative length of the waveform of the EMG signal from the ith-muscle over the time segment | [55] | ||
Difference absolute standard deviation value | x | R | Standard deviation of the cumulative length of the waveform of the EMG signal from the ith-muscle over the time segment | [55] | ||
Intra-limb coordination | Joint angle correlation | x | R | Correlation between shoulder flexion–extension and elbow flexion–extension joint time angles profiles | [68] | |
Elbow peak velocity | x | R | Highest value of the elbow flexion/extension joint velocity profile during movement | [43] | ||
Time to peak elbow extension angle | x | R | Time to reach peak extension angle for the elbow joint, relative to the duration of the movement | [69] | ||
Muscular synergies | x | R | Linear decomposition algorithm (e.g., principal components analysis, factor analysis, independent component analysis, and non-negative matrix factorization) to extract spatiotemporal, temporal, and spatial features from EMG signal of the muscles mainly involved in the task | [70] | ||
Co-contraction index | x | R | Percentage of overlapping activity of EMG linear envelopes between the agonist and the antagonist muscle involved in the task | [71] | ||
Intermuscular coherence | x | R | Square of the cross-spectra normalized with auto-spectra derived from the EMG signal from the agonist and the antagonist muscles involved in the task | [72] | ||
Movement amplitude | Joint range of motion | x | M | Range of the anatomical joints angles between movement onset and end | [73] | |
Maximum reached distance | x | R | Maximum distance reached from the starting position | [74] | ||
Trunk displacement | x | R | Euclidean distance covered by the trunk between movement onset and end | [75] | ||
Normalized reaching area | x | R | Maximally reached or reachable position during a movement or task divided by the length of the user’s arm | [76] | ||
Muscular effort | Integrated EMG | x | R | Summation of rectified EMG signal amplitude obtained from the ith-muscle | [55] | |
Root Mean Square | x | R | Square root of the mean square of the EMG signal amplitude obtained from the ith-muscle | [55] | ||
Activation level | x | M | Average of the absolute value of the EMG signal amplitude obtained from the ith-muscle in a segment | [77] | ||
Variance of EMG | x | R | Average of squared EMG signal amplitude obtained from the ith-muscle | [67] | ||
Mean absolute value slope | x | R | Differences between mean absolute values of the EMG signal amplitude obtained from the ith-muscle of the adjacent segments | [55] | ||
Planning predictability | Time to peak velocity | x | R | Time to reach peak velocity relative to the duration of the movement | [78] | |
Reaction time/Response latency | x | M | Time between the “Go” cue (as indicated by visual/acoustic feedback or any other channel) of a movement and the actual onset of the movement (e.g., 10% of peak velocity) | [62] | ||
Muscle onset | x | R | Time between the “Go” cue and the onset (e.g., detected by the Teager–Kaiser energy operator) of the EMG signal amplitude obtained from the ith-muscle | [79] | ||
Initial movement direction error | x | R | Distance between ideal and actual trajectory at an initial time point right after movement onset (e.g., 10% of peak velocity) | [62] | ||
Aiming angle | x | R | Angular difference between target direction and direction of travel calculated from starting point up to peak speed point | [80] | ||
Power | Mean frequency | x | R | Sum of the product of the power spectrum of the EMG signal from the ith-muscle and the frequency divided by the total sum of the spectrum intensity | [56] | |
Median frequency | x | R | Frequency at which the power spectrum of the EMG signal from the ith-muscle is divided into two regions with equal amplitude | [56] | ||
Mean power | x | R | Average power of the power spectrum of the EMG signal from the ith-muscle | [55] | ||
Power spectral density | x | R | Amount of power per frequency interval of the power spectrum of the EMG signal from the ith-muscle | [56] | ||
Frequency ratio | x | R | Ratio between the low-frequency components and the high-frequency components of the power spectrum of the EMG signal from the ith-muscle | [55] | ||
Power spectrum ratio | x | R | Ratio between the energy which is nearby the maximum value of the power spectrum of the EMG signal from the ith-muscle, and the energy which is the whole energy of the power spectrum | [55] | ||
Smoothness | Number of velocity peaks | x | M | Number of peaks (i.e., maxima above a certain threshold) in the velocity profile between movement onset and end | [81] | |
Speed correlation to idealized profile | x | R | Correlation between actual speed profile and idealized normal velocity profile (e.g., straight line) | [82] | ||
Movement Arrest Period Ratio | x | R | Proportion of time that movement speed exceeds a given percentage of peak speed | [83] | ||
Peak Speed Ratio | x | R | Mean speed divided by the peak speed | [83] | ||
Normalized dimensionless jerk | x | R | Time-integral of the squared jerk (i.e., third time-derivative of position) between movement onset and end normalized with respect to movement duration to the power of five and movement length to the power of two | [84] | ||
Spectral arc length | x | R | Length of the spectral trajectory (i.e., in the frequency domain) of the velocity profile between movement onset and end | [85] | ||
Mean acceleration | x | R | Mean value of the acceleration profile between movement onset and end | [86] | ||
EMG Zero Crossing | x | R | Number of times that amplitude values of the EMG signal from the ith-muscle crosses zero amplitude level | [55] | ||
Slope sign change | x | R | Number of times that slope of the EMG signal from the ith-muscle changes sign | [55] | ||
Speed | Peak velocity | x | R | Maximal value of the velocity profile between movement onset and end | [87] | |
Mean velocity | x | M | Mean value of the velocity profile between movement onset and end | [83] | ||
Mean velocity variability | x | R | Difference between the velocity profile of the participant’s reaching trajectory and the ideal velocity profile for each movement | [80] |