Gabrielle Reece, the former model and professional volleyball player, springs up from a squat while hurling a dumbbell over her head.

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Gravity takes over when you perform most exercises, like a dumbbell curl or a kettle bell swing, giving the body a chance to relax, says Rowdy Yates, a certified personal trainer and fitness manager at Crunch gym in New York City.

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The PowerBuoy generates 150 kilowatts of electricity and resembles a giant vertical dumbbell anchored to the sea floor.

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There were some kettle bells lying around, like cannonballs with handles attached, and a clumsy-looking thing called a Thomas Inch dumbbell.

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His dumbbell, made of cast iron, weighed a hundred and seventy-two pounds and had a handle as thick as a tin can, difficult to grasp.

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Using his right arm only, he proceeded to lift a two-hundred-and-fifty-five-pound circus dumbbell above his head five times.

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