The phrase "proud chest" refers to someone standing tall and confidently, with their chest pushed out. It represents a sense of pride and self-assurance in oneself. Full definition
When training, think about maintaining a «proud chest posture,» meaning elevating the chest somewhat. (onnit.com)
Maintaining that rotated bent arm position, squat with a tall spine and forward oriented proud chest as you tuck the tailbone back slightly. (onnit.com)
Anyway, as I have said so many times in the past few months of 215 - proud chest beatings, Philly is on an unstoppable wave fueled by passion and Yuengling and it's coming to a city near you. (sbnation.com)