If your goal is to strengthen your abdominal core and arms, without a doubt, the plank exercise is the one that targets both areas the best. As with many other types of exercises, there are several variations with each one targeting a specific area. Because our focus is the core and arms, the forward and side plank exercises target these two areas specifically.
Beginners should start out with the Forearm Plank and then move into the Straight Arm.
Start out by laying on the floor face-down with feet shoulder-width apart. Raise yourself so you are supported on your forearms. Now by pulling in your abdominal core, raise up the rest of your body so your body is in a straight line from your head to heels (straight like a plank of wood). Hold for 60 seconds or longer if you can. This plank tends to work the core more so than the arms.
This one starts out basically the same, but instead of supporting yourself on your forearms, your arms are straight and fully extended – like at the top of the push-up position. Your body should still be in a straight line. This one works both arms and core, but may be too demanding in the beginning. In that case, start out with the Forearm and work up to this one. Also hold for 60 seconds or as long as you can.
The Side Plank starts out with the Straight Arm, but then you turn your body so you are supporting it with just one arm and leg, with the rest of your body in a straight line from your shoulders to your feet. If turned to the right side, your left foot should rest on the inside of your right foot; left arm should be extended with your hand pointing up. Hold for 60 seconds or longer; do three reps. Rest and then do the same exercise again, but use your other arm and leg.
If looking for a challenge, this one will test you to the max. Start out in the Straight Arm and move into the Side. But instead of holding it go back to the Straight Arm and do a Side Plank on your other side. Return back to the Straight Arm. That is one rep. Try doing 12 reps. Because of the constant movement, this one ultimately works both arms and core the best because the shifting weight targets both arms and the abdominal core muscles used in the process. This is one exercise that you will want to work up to by first doing the Straight Arms and Side Planks individually until you have first worked your abs and arms to gain some strength.
While all of these planks are performed just using bodyweight, small dumbbells can be held while doing Side Planks and resistance bands around your ankles and/or wrists while doing the Forward Planks to make these exercises more demanding.
As with other plank exercises, keep your body in a straight line; no sagging, slooping or arching of the back! Think of your body as a solid rigid plank of wood.