Effects of sustained moderate exercise on cholesterol, growth hormone and cortisol blood levels in three age groups of women

Abstract

Objective: The objective of this study was to determine the effects of sustained moderate exercise on cholesterol, cortisol, and growth hormone blood levels in women of three age groups.

Design: A four-week exercise program followed by one week of no exercise. The exercise program consisted of 20 minutes of moderate exercise three times a week for four weeks. Venipuncture was performed weekly.

Setting: The exercise and venipunctures took place in a large room with phone access and ample space to move.

Participants: A convenience sample of five pre-menopausal (20 to 30 years), 11 peri-menopausal (40 to 50 years), and 9 post-menopausal (60 to 85 years) healthy women participated in the study.

Main outcome measures: Paired samples t-tests were used to compare changes in cholesterol, growth hormone, and cortisol of individuals from week zero (pre-exercise) to week four (last exercise) to week five (one week post exercise).

Results: There were no significant differences between pre-exercise and post-exercise growth hormone levels for post-menopausal women, however, there appeared to be a trend in growth hormone increase over time. There were no significant differences between pre-exercise and post-exercise cholesterol levels for any of the three age groups of women but trends for decreased cholesterol levels were observed in the peri-menopausal and post-menopausal women. Cortisol levels did not appreciably change in response to regular exercise.

Conclusion: Although this study did not generate definitive data there were trends toward the proposed hypotheses. Future studies may include increasing the number of participants, implementing a longer test period to validate exercise-induced increases in growth hormone and decreases in cholesterol levels, and employing insulin-like growth factor (IGF-1) as an indicator of growth hormone levels.