Can You Perform Muscle Control Feats! – Strength Magazine – April, 1927

Why do they go in for muscle control? Because they know that by acquiring the knack of controlling their muscles (which means contracting and relaxing a muscle or group of muscles at will and without moving the bones) they impart to their muscles a clean-cut appearance. Besides, such feats are used in muscular posing, and they cause an audience to marvel at the wonder of such posing.