You can try smoothing the plot using maybe gaussian smoothing and then use the smoothed values to determine the local minimums. That would cause only heel strikes to appear. Alternatively, you could parse the mouse input pixel from the graph (see documentation for ginput) and search the closest heel strike point to it in another MATLAB script.
clicked_point = ginput(1);
closest_point = [NaN, NaN];
minDist = Inf;
for idx = 1:length(heel_strike_points)
if dist(clicked_point, heel_strike_point(idx)) < minDist
minDist = dist(clicked_point, heel_strike_point(idx));
closest_point = clicked_point;
end
end
