A simultaneous development further broadened the appeal of swimming. Urban Americans became increasingly conscious of the virtues of physical fitness during the mid-nineteenth century. Many commentators concluded that city life and sedentary occupations were eroding the health and weakening the strength of the nation’s urban population, especially middle-class men. To cure their frailty, doctors and even preachers prescribed weight lifting, calisthenics, gymnastics, and swimming. “For this once,” Thomas Wentworth Higginson encouraged Atlantic Monthly readers in 1861, “lock your brains into your safe, at nightfall, with your other valuables; don’t go to the Chess-Club; come with me to the gymnasium.” Termed “muscular Christianity,” the midcentury fitness movement also had a spiritual dimension, which helped overcome earlier associations of physical stimulation with sin. Devotees linked exercise with postmillennialism, believing that strengthening the body was a prerequisite of progress and human perfection. “The soul is made healthier, larger, freer, stronger,” Higginson claimed, “by hours and days of manly exercise.” Exponents of muscular Christianity identified swimming as a particularly beneficial form of exercise. Higginson referenced swimming throughout a series of Atlantic Monthly articles, suggesting at one point that it was the best form of outdoor exercise. Unlike most activities, he explained, swimming strengthened the entire body.
Jeff Wiltse, Contested Waters.