Dear Allan,
Based on your valuable comment I think the best method to extract peak values of kinematic and kinetic measures of my study will be using the vertical position of the heel and toe markers, so is it correct to assume that the period between HS frame and the first frame which has the lowest vertical position (zero z value I think) for both Rt heel marker and Lt toe marker is the first Double limb support, the period between the second frame with lowest z value for Rt toe marker and Lt heel marker and the TO frame is the second double limb support and the remaining frames will belong to single limb support?

I really appreciate your time and consideration