Once dismissed as a gimmick, vibration machines have gained popularity with pro athletes and ­celebrities; and now, with new research about potential health benefits, they are making their way into health clubs and mainstream retailers. The latest generation has platforms that vibrate 25 to 50 times a second, which stimulates rapid muscle contraction. As a result, you expend more energy, and the ­intensity of any weight-bearing exercise or stretch is amplified. This fall, ­researchers found that mice placed on low-frequency vibration platforms not only developed greater bone density but also had less body fat than a control group. Juvent, a small ­company in Somerset, New Jersey, already markets a low-intensity platform called the Juvent 1000, which is undergoing F.D.A. trials as a treatment for ­osteoporosis. Meanwhile, two home-gym versions, which vibrate more frequently and with greater force, have developed a cult following among athletes like Curt Schilling, Alex Rodriguez, and LeBron James.

VibraFlex Home Edition

Price: $4,950

Key feature: A metal platform that teeters back and forth across a fulcrum. The New England Patriots train with a commercial version of this machine.

Downside: Capable of generating forces of up to 11 G’s, it will rattle the fillings in your teeth.

Power Plate My5

Price: $4,500

Key feature: Vibration in three dimensions, at varying speeds. Madonna is reportedly a fan.

Downside: Moving the 200-pound machine is a workout in itself.

Battle Creek Flashback

Dr. John Kellogg's sanitarium was an early innovator of gym equipment in the 1920s.

With such celebrity clients as Eleanor Roosevelt and Amelia Earhart, Battle Creek Sanitarium was like an old-school Canyon Ranch. Modern-day breakfast cereal was invented there, along with some less successful products, like the Battle Creek Health Builder (pictured above, left). “Exercise without effort,” promised a 1928 ad campaign for the machine, which resembles an industrial KitchenAid mixer with a belt attachment. Look for antique models on eBay.