How to determine muscle activation timing of an emg signal?

Are there any matlab toolboxes to determine onset and offset of an emg signal in order to evaluate muscle activation timing?

[H W]

Biceps = [10 : 35];

Triceps = [100 : 200];

figure;

polarplot(Biceps*pi/180, 0.7*ones(size(Biceps)), 'y', 'LineWidth',1.5);

hold on;

polarplot(Triceps*pi/180, 0.5*ones(size(Triceps)), 'g', 'LineWidth',1.5);

hold off;

set(gca,'ThetaZeroLocation','bottom', 'RLim',[0 1]);

legend('Biceps', 'Triceps', 'Location','NorthEastOutside');

Answer 1

[MarKf]

You can use Fieldtrip or something like below (code needs testing/cleaning)

% emg = timeseries;
% Fs = sampling frequency
% Fn = Nyquist frequency, Fs/2;
% filter, hilbert and boxcar 
[B, A]      = butter(6, 10/Fn, 'high');                 % 6th order butterw 10hz highpassfilter
emgflt      = filtfilt(B, A, emg);                      % twopass
emghlb      = abs(hilbert(emgflt));                     % hilbert transform
emgcnv      = conv2([1], ones(1,Fs), emghlb, 'same');   % smooth using convolution
emgstd      = (emgcnv - repmat(mean(emgcnv), 1, length(emgcnv))) ./ ...
            repmat(std(emgcnv), 1, length(emgcnv));     % z-transform
emgtrl      = emgstd>0;                                 % detect the muscle activity
emgtrl      = diff(emgtrl, [], 2);
emgon       = find(emgtrl(:)== 1);
emgoff      = find(emgtrl(:)==-1);