James Pieratt - History’s Best Physical & Mental Training on Instagram: "Jack Dempsey’s savage knockout power and unbreakable cardio both came from his INSANE workout routine: His training went beyond the standard calisthenics and roadwork with brutal methods: •running alongside trains to build endurance •punching trees without gloves to build strength in his hands •submission wrestling in the ‘catch wrestling’ style (Dempsey was accomplished striker and grappler, known then as a ‘Combination Ma