Do you remember Face-o-Metrics? How about FloMotion? Or kitchen calisthenics? Me neither. But The Times recorded these and many, many other modern fitness fads, an exhausting and often poignant chronicle of pain, gain and some very peculiar practices. Taken as a whole, the papers coverage of the last half-century of exercise recalls the old joke, Samuel Johnson by way of Oscar Wilde, about second marriages: a triumph of hope over experience.