Lying flat, stretching or moving in a new way may look different from how your dog usually sees you. A bark alone does not tell you whether they are excited, startled or worried. Do not keep repeating the pose while they shake, rush your face or cannot settle.
Give the dog a comfortable place away from your exercise mat and let them leave the room. If they approach your face or mouth, pause and make space rather than pushing them away with a hand. The article on reading whether a dog wants play helps you look at the whole body and the ability to take a break, not infer an emotion from noise alone.
When nobody needs to exercise, try a mild part of the movement at a distance where the dog remains relaxed. Sit on the mat, reward calm observation, then stand up. Lying flat can come later if earlier movements are easy. If your dog trembles, hides or barks harder, stop and give more distance next time. A qualified reward-based trainer can help if the reaction is intense, and a new broad behavior change deserves a vet check.
Today, move your exercise area away from the dog's resting spot. You can keep working out without requiring them to share the mat.
Sources: Dogs Trust on barking triggers and calm alternatives, VCA on fear of unfamiliar people or movements, Dogs Trust on comfort-based handling.