Influence of Estradiol Status on Physical Activity in Premenopausal Women

ABSTRACTPurposeTo determine the effects of 5 months of ovarian hormone suppression in pre-menopausal women on objectively measured physical activity (PA).MethodsParticipants (age = 35±8 yr; body mass index = 27±6 kg.m-2) received monthly intramuscular injections of gonadotropin releasing hormone agonist therapy (GnRHAG) which suppresses pituitary gonadotropins and results in suppression of ovarian sex hormones. Women were randomized to receive concurrent transdermal E2 (GnRHAG+E2; n=30) or placebo (GnRHAG+PL, n=31). PA was assessed for 1 week before and during each month of the 5-month intervention using a hip-worn accelerometer (Actical, Mini Mitter Co., Inc., Bend, OR). Estimates of time spent in sedentary, light, and moderate-to-vigorous physical activity (MVPA) were derived using a previously published equation. Subsets of participants in each group were also randomized to a supervised progressive resistance exercise training program.ResultsTotal MVPA tended towards being higher (p=0.08) in the GnRHAG+E2 group at month 4. There were no significant effects of intervention or time in sedentary or light PA. In the subset of women who did not participate in structured exercise training for which Actical data were obtained (N=16 in each group), total MVPA was higher at month 4 (p=0.01).ConclusionPhysical activity levels appear to be maintained at a higher level in women undergoing pharmacological suppression of ovarian function with E2 add back when compared with women treated with placebo. These data provide proof of concept data that E2 contributes to the regulation of PA in humans. However, given the exploratory nature of this study, future confirmatory investigations will be necessary. Purpose To determine the effects of 5 months of ovarian hormone suppression in pre-menopausal women on objectively measured physical activity (PA). Methods Participants (age = 35±8 yr; body mass index = 27±6 kg.m-2) received monthly intramuscular injections of gonadotropin releasing hormone agonist therapy (GnRHAG) which suppresses pituitary gonadotropins and results in suppression of ovarian sex hormones. Women were randomized to receive concurrent transdermal E2 (GnRHAG+E2; n=30) or placebo (GnRHAG+PL, n=31). PA was assessed for 1 week before and during each month of the 5-month intervention using a hip-worn accelerometer (Actical, Mini Mitter Co., Inc., Bend, OR). Estimates of time spent in sedentary, light, and moderate-to-vigorous physical activity (MVPA) were derived using a previously published equation. Subsets of participants in each group were also randomized to a supervised progressive resistance exercise training program. Results Total MVPA tended towards being higher (p=0.08) in the GnRHAG+E2 group at month 4. There were no significant effects of intervention or time in sedentary or light PA. In the subset of women who did not participate in structured exercise training for which Actical data were obtained (N=16 in each group), total MVPA was higher at month 4 (p=0.01). Conclusion Physical activity levels appear to be maintained at a higher level in women undergoing pharmacological suppression of ovarian function with E2 add back when compared with women treated with placebo. These data provide proof of concept data that E2 contributes to the regulation of PA in humans. However, given the exploratory nature of this study, future confirmatory investigations will be necessary. Corresponding Author: Edward L. Melanson, Ph.D. (Ed.melanson@ucdenver.edu)MS 8106, 12801 East 17th Ave, RC1 South RM 7103, University of Colorado Anschutz Medical Campus, Aurora, CO 80045 Grant support: Supported by NIH grants P50 HD073063, R01 AG018198, P30 DK048520, UL1 TR001082, and K01 DK109053. Drs. Melanson, Kohrt, and Schwartz are also supported by resources from the Geriatric Research, Education, and Clinical Center at the Denver VA Medical Center Conflict of Interest: The authors have no conflicts to declare Accepted for Publication: 22 February 2018 © 2018 American College of Sports Medicine

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