ASA
Description
Analysis of anticipatory synergy index and Anticipatory synergy onset time according to UCM hypothesis. 20 trials of forehand stroke in both fast and slow stimulus were performed by 10 novice participants and 10 skilled athletes. and muscle modes covariance that stabilize cop performance calculated in ASA time interval before action onset time. up to the forth folder, only the data of two representative participants are added (according to numerous files) including 1. skilled participant perform fast, 2. skilled participant perform slow, 3. novice participant perform fast, 4. novice participant perform slow. however from folder number 5 up to the end, the cumulative data of all participants are included.
Files
Steps to reproduce
Acceleration and EMG signals were filtered (50 Hz second-order low-pass Butterworth) in MATLAB and rectified to full waveform. The acceleration value >=0.01 of the peak acceleration was selected as the onset time (t0). The equivalent of this moment was found in the EMG and the data of -500 ms before the t0 was selected and divided into: the steady-state phase (-500 to -300 ms), and the ASA phase (-300 ms to t0). COP data were filtered (20 Hz low-pass second-order Butterworth) and smoothed. The time-varying COP coordinates in the AP direction are calculated: COPAP= (-MY + (FX.dZ))/ FZ Then calculate the net COPAP from each of the right leg (R) and left leg (L): COPNET-AP = [COPL-AP× (FZ-L / FZ-L+FZ-R)] + [COPR-AP× (FZ-R / FZ-L+FZ-R)] Principal component analysis (PCA) was performed with varimax rotation and factor extraction. The factor loading in PCA was > ±0.5. The first four components were selected as the PC. To calculate the amplitude of muscle modes, the eigenvectors were multiplied by the equivalent IEMG data. (M-mode) ̅ = M-mode × IEMGC-N The regression equation for changes in the COP due to changes in muscle modes was obtained: ΔCOPAP = (K1× ΔM1) + (K2× ΔM2) + (K3× ΔM3) + (K4× ΔM4) The Jacobian matrix of the unstandardized coefficients is written: J = [K1 K2 K3 K4] T The null space of the Jacobian matrix is calculated. The null space is spanned by the basis eigenvectors (iε). Demeaned time vector calculated: ΔMdemeaned = ΔM – (M-modes) ̅ projection of the demeaned muscle modes vector parallel and orthogonal to the null space is calculated. fucm = ∑_(i=1)^(n-d)▒ (εiT× ΔMdemeaned)T × εiT fort = ΔMdemeaned – (fucm)T trial-by-trial variance of each of subspaces (VUCM, VORT) and the total variance (VTOT) normalized by the number of degrees of freedom: VUCM = σ2UCM = 1/(n-d)N ∑_(i=1)^N▒ |fUCM|2 VORT = σ2ORT = 1/dN ∑_(i=1)^N▒ |fORT|2 VTOT = σ2TOT = 1/(n+d)N ∑_(i=1)^N▒ |ΔMdemeaned| Calculate VΔ as an index of synergy: ΔV = (VUCM – VORT) / VTOT To normalize the synergy index, Fisher's z equation according to the ΔV bounds: ΔVZ = 1/2 × Log [(4+ΔV )/(1.33-ΔV )] When the difference in ΔVZ (ΔΔVZ) is > 1 SD from the mean of this value over the ASA time is considered as tASA
Institutions
- University of Tehran