The man who stoops is the man with no energy. The woman who puts her hands on her hips is too aggressive for the audience. The person who stands straight and walks with the head held high is the one who is seen as confident.
What you just read are examples of postures in presentations. If you are speaking in front of an audience, your posture speaks louder than your words. A posture that communicates confidence, enthusiasm and energy, will keep the audience focused on you. No one likes to watch a tired and low energy person giving a presentation or talk.
Observe yourself in the mirror and try different postures. You will understand to a large extent which postures communicate what meaning. Take this seriously as this would create an important part of your image as a speaker.
Are you displaying the right postures during your presentations?