Starting Position: Kneel on an exercise mat or floor with your feet together behind you; toes tucked under to prepare for push up position. Slowly bend forward and place your palms on the sides of a medicine ball. Carefully shift your weight forward until your shoulders are positioned directly over your hands and the medicine ball, coming to a full plank position. Reposition your feet as needed to help achieve a rigid bodyline from head to toe. Do not allow your body to sag downward or hips to hike upward. Keep the torso rigid by contracting your core and abdominal muscles. Your head should be aligned with your spine.
Downward Phase: Slowly lower your chest toward the ball. Keep the torso rigid and head aligned with your spine. Do not allow your body to sag or your hips to hike upward. Contract your glutes (butt) and quadriceps (thigh) muscles to help maintain stability. Continue to lower yourself until your chest nears or lightly touches the ball. Your elbows should either remain close to the sides of your body or flare outwards slightly.
Upward Phase: Press upwards through your arms. Keep the torso rigid and head aligned with your spine. Do not allow your body to sag or your hips to hike upwards. Continue pressing until the arms are fully extended at the elbows.
An alternate ball with handles can be substituted, which reduces the pressure on your wrists. When using this type of ball, maintain a neutral wrist position throughout the exercise.
As the ball adds instability to this exercise, your movements need to be slow and controlled to reduce the chance of injury.