Pushups are a fundamental upper body exercise commonly done in gyms, boot camps and military workouts. Pushups work several muscle groups in the upper body and don't require any extra equipment. They have numerous variations that you can do to make the exercise easier or harder. Knee pushups are a modification of the standard pushup that are easier to perform.
A standard pushup has a medium difficulty level compared to other pushup variations. Start with your palms flat on the ground and extend your legs behind you so your weight is on your toes. Make sure your body is in a straight line from your neck to your ankles. Position your hands so your wrists are stacked directly below your shoulders. Lower your body by bending your elbows keeping your body rigid and moving it as one unit. Lower until your upper arms are about parallel to the ground, then press back up, straightening your elbows.
Kneel on the floor on your hands and knees. Walk your hands forward until you can drop your hips. Stop when your body is in a straight line from your shoulders to your knees. Your wrists are lined up beneath your shoulders. You can rest your feet on the floor or cross your ankles and have your feet in the air. Knee pushup are performed in the same manner as the standard pushup except you are on your knees instead of your feet.
The knee pushup exercise is an easier modification of a standard pushup. During a standard pushup, you press up your entire bodyweight as one unit. The knee pushup variation reduces the resistance of the exercise since you are on your knees and don't have to push the weight of your lower legs. There is also less of your body fighting gravity when doing push ups from the knees. You can also push your hips back during a knee pushup, making the exercise even easier. This results in you only pressing up your chest and shoulder area and takes the weight of your hips out of the exercise.
If you can't perform a standard pushup with good form, start with knee pushups. Work your way up until you complete 20 to 25 repetitions with good form. This means keeping your hips in line with your body and not letting the hips sag towards the floor or push your butt up towards the ceiling. Once you can do at least 20 good knee pushups, move to standard pushups. Start with as many repetitions as you can with good form, then move to bent knee pushups to do a total of about 20 pushups. Gradually increase the number of standard pushups you do until you can complete an entire set.