Graphic analogies have been drawn between human coitus and other forms of energetic activity, such as riding a bicycle or running a sprint. In all such cases various physiological effects can be noted, one of which is the more rapid circulation of blood. In the 1950's Kinsey pointed out that "precise measurements on the increase in pulse rate during arousal are few," a circumstance which - to a degree Masters and Johnson have rectified. Mendelsohn produced graphs showing maximum pulse rate for men and women before, during and after coitus: a maximum pulse rate of 150 was recorded. Boas and Goldschmidt recorded maximums of 146 in four consecutive orgasms in a woman. And Klumbies and Kleinsorge noted a maximum pulse rate of 142 in a man at orgasm. In violent exercise boys have been known to reach a rate of 200; and young men running to a treadmill have reached 208.