A demanding guide to physical fitness for children, which covers not just exercise but diet as well, and recognizes that girls--whose needs have been slighted in the past--require as much regular activity as boys. Dr. Lorin, a pediatrician, maintains that all children need some form of aerobic exercise. He recommends running (even two year olds can do it) but admits that sports such as swimming or tennis are generally more enjoyable. He also indicates which sports have virtually no fitness value (bowling) or surprisingly little: the training for football is superior to football itself. Most parents will find more here than they anticipate: Dr. Lorin advises them to design a complete program around their children's current interests and activities. It's not an Olympics regimen, but the standards are high. Also included: essentials on food components, vitamins, fiber, and the par. ticular needs of--and most serious dangers to--specific age groups. One minor criticism: the chapter on additives could be more comprehensive. Only nitrates and PCBs--whose hazards are well publicized--are named; the consequences of lesser known substances might have also appeared. Otherwise, a dependable reference.