This pose is a strong pose for the upper body. What makes this pose different is slightly bending the elbows and pulling the floor towards the feet. This requires much more muscle than simply holding the pose.
This basic yoga pose can be very challenging. I recommend keeping the elbows slightly in towards your ribs. Not touching the ribs. Keep your legs firm and lower down. Try not to bend your back. Put your knees down if it is too hard to support your body weight without bending your lower back.. This leeds to Upward Dog Yoga pose. Watch Plank Yoga Pose and Upward Dog Yoga Posture below.