10 Innovations That Changed the Way We Exercise

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Personal Trainers

Before personal trainers rose to their current level of ubiquity, weightlifters who'd watched Ah-nold at Gold's Gym in the 1977 film Pumping Iron would ask gym employees—or the guy in the best shape—for help. Today's trainers "trick" muscles through periodization—changing up a workout so the body doesn't have time to adapt—while also providing accountability, injury prevention, and general guidance. Some exercises involve complex movement patterns, says Mike Fantigrassi, a specialist with the National Academy of Sports Medicine. As with a sport like golf, "it takes coaching to do something right if you haven't done it before," he says.