The Bottom Line On Exercise

The Bottom Line on Exerciseeven as Jane Fonda and other gurus of sweat were imprinting their leotarded images on the national consciousness, even as the home fitness business was beginning to rival the arms industry in annual sales, even as joggers were shouldering automobiles off the roads, even as more and more seemingly sane people engaged in such seemingly masochistic pursuits as the Ironman Trithlon, the rumblings were starting: Does this stuff really do any good?And then, in the summer of...