10 Innovations That Changed the Way We Exercise

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Plate-Loaded Barbell

Alan Calvert's Milo Barbell Company began to offer its adjustable barbells at the turn of the 20th century, giving rise to progressive resistance training. Before then, bodybuilders lifted fixed weights. "When people could change the plates and incrementally add weight, it made it easier for them to see their progress and train," says Jan Todd, a professor in the Kinesiology and Health Education department at the University of Texas at Austin. Today, plate-loading free weights and machines such as chest presses, shoulder presses, and leg curls save gym owners countless square feet of floor space.