Going the Distance C

While others engage in ""thrusting and twisting like frenzied disco dancers,'' Lawrence and Rosenzweig's (he specializes in sports medicine; she is a medical writer) proteges will be cycling, swimming, skiing and kayaking, absorbed in ``the exhilaration of moving.'' This encouraging guide to midlife exercise tartly rejects Jane Fonda-type calisthenics as drudging and of inferior aerobic quality. Readers can learn how to weather the elements and ailments (arthritis, asthma, diabetes), as well as how to select beneficial indoor and outdoor sports, and test and buy the appropriate equipment. There are lucid five-minute exercise lessons with schedules that regulate the beginner's progress and first-aid tips. But this otherwise sensible and informative guide is spiked with feeble wit and profiles of born-again athletes, and provides a simplistic explanation of the mechanisms by which aerobic exercise is allegedly a boon to heart, complexion and taut nerves, etc. Illustrations not seen by PW. (March 23)