Fitness as we now understand it became fashionable then too, as Jürgen Martschukat’s fascinating history shows. By 1915 the expression “keep fit” was in widespread use, a US sports magazine reported. Especially in America, Martschukat argues (in Alex Skinner’s translation), “the activation of the body, and especially the white male body”, was the necessary response to the threat to white supremacy represented by increasing immigration to the US. This equation of physical exercise with national purity, of course, reached its apex in Nazi Germany, as the author describes. But that does not mean our modern concept of fitness is ideologically neutral, or indeed freely chosen.