There is a really nice thing about human hands: Almost everyone has them and they are impossible to drop, unlike pepper spray, a knife, or any other hand-held weapon. You also can’t forget them in your purse in a moment of attack. For this reason, they can be far more reliable than a hand-held weapon, especially with proper training.
Straight Punches can be made with either hand. It is common in Krav Maga (and other sports) to call the left punch a “Jab” and the right punch a “Cross.” Whether performing a Jab or a Cross, the basic principles of the punch are the same for either hand. In other forms of martial arts and fighting, the Jab is used as either a distraction punch (used in a quick tapping motion that does not have a lot of power behind it), or it is used to determine the distance between you and an opponent. In Krav Maga, students are taught to make every attack count. So a left Jab in Krav Maga is meant to do damage, not just distract or disturb your opponent. Keep this in mind during your training sessions.
A Straight Punch is a medium-range weapon, so be sure you are standing with enough distance from your target to extend your punch all the way out without jamming yourself. You should be a little more than one arms length from the target.
When performing a Straight Punch, as the hand travels forward it’s important to keep the elbow down as long as possible. This ensures the punch travels in one straight line, which is the shortest distance to the target. It also makes a smaller, less detectable movement and keeps the ribs protected for a longer period of time while delivering the strike. As you send the punch, the shoulder and hip rotate forward adding reach and power to the punch.
Contact is made with the first two knuckles, keeping the wrist straight. Recoil the hand quickly back to its starting position following the same path it was delivered on. Once you are comfortable with this movement you can tuck the chin and rotate the shoulder on the punching side up to protect the jaw.
The left Jab is usually not going to feel as strong as the right Cross. This is because the right Cross has a further distance to travel before making contact, and during that time it is able to gain velocity. You should still train with the purpose of making your left punch just as strong as your right punch.
Begin in a Fighting Stance, and as the left hand moves forward into the punch, use the legs by pushing off the ground and rotate the left shoulder and hip forward. Extend the punch all the way out and recoil back to your starting position.
One last thing to think about when sending a punch (or any attack) is to try to send your punch through the pad rather than tapping the surface of the pad. In order to do this well you have to have your weight behind your punch at the point of impact. It will make your punch have a great deal of power.