It doesn’t get any more “Old School” than De Arte Gymnastica by Hieronimus Mercurialis. Published in 1569, this is the oldest book ever written on physical training. It describes exercises as practiced by the classical Greeks and Romans: the value of walking, throwing the discus, climbing ropes, training with heavy balls (i.e. Medicine Balls) and, as seen in the wood cut above, dumbbells and heavy stone tablets called “plummets” — history’s first odd object lifting!