Makers of popular exercise equipment, including Abflex and Lifecycle, agreed to settle federal charges that they made exaggerated weight-loss claims in advertisements. The Federal Trade Commission reached separate settlements with Franklin Park, Ill.-based Life Fitness Cos., maker of Lifecycle stationary bikes, and Logan, Utah-based Icon Health & Fitness Inc., maker of Cross Walk treadmills, prohibiting those companies from making unsubstantiated calorie-burning claims. The FTC also reached agreements with two California firms that market Abflex abdominal exercisers--Carlsbad-based Abflex U.S.A. and Culver City-based Kent & Spiegel Direct Inc.--banning them from making unproven claims about weight loss and spot reduction. Manufacturers sold $2.4 billion worth of exercise equipment in 1996, up 4.4% from 1995, the FTC said. Treadmill sales accounted for the largest bulk of that amount, and abdominal exercisers represented the fastest-growing category. A Life Fitness spokeswoman said the company agreed to the settlement to avoid "a protracted dispute with the government." The other companies weren't available for comment.