When it is recommended that I should keep my back straight, does it mean that my back should be vertical, like perpendicular to the floor?
Or if can I keep my back straight, but slightly leaning forward? I tried to keep my torso perpendicular to the floor, but I always feel like I'm in danger of keeling over backwards
Or if can I keep my back straight, but slightly leaning forward? I tried to keep my torso perpendicular to the floor, but I always feel like I'm in danger of keeling over backwards