The data in the paper states that the relative risk of stroke suffered by men is 0.84 for each 5cm increase in height; and the corresponding risk for women is 0.73.
Thus, for each 1m increase in height, the relative risk is raised to the 20th power. For men, it is 0.03; and for women, it is 0.002.
To normalize the relative risk, so that the average man or woman would have a relative risk of 1, the final relative risk for men is thus adjusted to 0.03^(Height-Mean Height of Males); and the final relative risk for women to 0.002^(Height-Mean Height of Females)
This final relative risk is multiplied to the lambda value for stroke at all ages to get the new lambda value for stroke.