On another thread, a question about the technique for Mach Bs was made. Mach Bs can be performed various ways depending on the goal (dynamic flexibility enhancement, sprint cue development, hip strength, etc.) but here’s the way that is probably the closest simulation of what happens in sprinting: hit a Mach A position and then rapidly accelerate the thigh down. This rapid and forceful acceleration will result in the lower leg “opening up” at the knee joint. Ground contact should be made close to under the center of mass.