'For a wager a hundred yards': Sir John Floyer's controlled trial of the effect of cold water upon athleticism (1702).

Sir John Floyer (1649-1734) was an English physician and author, notable for developing the pulse watch, advancing understanding of asthma pathophysiology, the first pathological description of emphysema and as an advocate of coldwater bathing. In 1702, he published a book with Edward Baynard MD (c1641-1717) on coldwater bathing. Therein, a postscript to a letter by Baynard describes a controlled trial of water therapy using two boys of 'near of a Speed and Strength' to race 100 yards. After immersing the loser in cold water, the race should be re-run. Now the immersed loser emerges as victor. Textual evidence suggests that its author was Floyer rather than Baynard. That the experiment took place is implied by Floyer's certainty in its outcome. It may have served as an 'exhibition' to promote his coldwater treatment. Floyer does not appear to repeat his controlled trial in his other books. He does, however, record basic observational comparisons of the effects of age, sex, diet, and month upon pulse rate. He also places data in basic tables and recognises normal variability ('latitude') in pulse rate. By linking ranges of pulse rate to clinical outcome, Floyer's work envisions modern clinical decision-making tools.