A pushup plank is a body-weight exercise that works your core muscles, abs and lower back. The pushup plank is an isometric exercise, meaning your muscles don't actively contract like during a crunch. The pushup plank has several variations. It is held for a length of time, rather than performed repeatedly, and resembles the top position of a pushup.
Kneel on a mat and place your palms flat on the floor, shoulder-width apart. Lift your knees off the mat and support your weight on your hands and toes. Make sure your hips are not sagging or lifting; keep them in line with your body. Shift your body weight, if necessary, so your shoulders are stacked above your wrists, not in front of or behind your wrists. Hold this pose and breathe normally. This is the pushup plank; it does not involve any active movement once you get into position.
The pushup plank mainly targets your rectus abdominis, your most visible ab muscle, your transverse abdominis, which lies under your main ab muscle, and your erector spinae, the muscles of your low back. However, several other muscle groups assist in holding the pushup plank, including your shoulders, quadriceps and upper back muscles. To properly activate your abdominal muscles during a plank, you need to perform an "abdominal brace." Pull your belly button up to your spine. This activates your abs without any actual movement of the muscle.
Although the pushup plank is typically done with your arms fully extended, you can perform this exercise on your forearms. This releases the pressure on your wrists. Place your feet on a stability ball and your hands flat on the ground to do a more unstable version of the pushup plank. You can also integrate pushups with the plank. Hold the plank for 30 to 60 seconds then perform three to five pushups. Continue for five to 10 reps.
Keep your body in a straight line when doing the pushup plank. If you allow your hips to sag, this places undue stress on your low back. The American Council on Exercise cautions you to immediately stop the exercise if you feel any pain in your low back. Keeping your body rigid and activating your abdominal muscles with the abdominal brace technique helps protect your low back during the pushup plank exercise.