Little attention has been paid to the study of transient growth hormone (GH) responses to exercise in older women. We determined the effect of a single bout of exercise on GH in fit and unfit older (age 55 to 81 y; n = 19) and younger (age 18 to 25 y; n = 19) women.
Exercise consisted of five 15-min intervals of treadmill exercise at 75% VO2peak. Blood samples were taken before, during, and following exercise for determination of plasma GH and insulin concentrations.
GH responses to exercise were attenuated in older compared with younger women (P < 0.01); however, these age differences were minimized in older age by fitness level. Adjusted area under the curve for GH was 5.50 and 1.76 µg/L · 102 for fit and unfit older women (P < 0.01), and 8.46 and 8.46 µg/L · 102 for fit and unfit younger women.
Low levels of cardiorespiratory fitness in older women may require a greater relative exercise stimulus to augment meaningful GH responses.