The effect of ambient temperature on the growth hormone and prolactin response to exercise

The effect of a standardised exercise procedure on plasma growth hormone (HGH) and prolactin has been assessed in 10 normal human subjects. Each subject was tested in an ambient temperature of 40 degrees and on a subsequent day at a temperature of 10 degrees. At 40 degrees exercise produced an increase in HGH in all 10 subjects, while in the cold only 1 showed a rise in the hormone during exercise. An increase in prolactin with exercise at 40 degrees occurred in some of the subjects, but these changes were small in comparison with those of HGH. Prolactin levels did not increase during exercise in the cold.