We do cross punch for 30 seconds, followed by jump ropes for 30 seconds and we do the same routine twice over. Let's go. For a cross punch take a wide feet stance and punch fists side to side with energy. Holding the abdominal muscles in, twisting the torso, keeping a very solid lower body every time you punch. Keep in mind not to lock your elbows while punching. This could lead to an injury. Punching is a very strong exercise. We are using it as a cardiovascular exercise by doing it fast so it increases stamina, power and speed. This particular exercise works on the abdominal muscles, mainly the obliques and the punching action tones the arms..