Estrogen, Progesterone, and Exercise Metabolism: A Review
By: Emily Caruso, DO
Editor’s Note: Happy 2023 from our FACTS Team! It’s an exciting time as we have officially become our own independent organization, FACTS about Fertility, Inc. Stay tuned for important updates about how to renew your FACTS membership and support our mission in 2023!
Also, as we embrace the new year and create lifestyle resolutions for the months ahead, we are highlighting a review of an article published by Oosthyuse et al. in Sports Medicine. [1] The article, “The effect of the menstrual cycle on exercise metabolism: implications for exercise performance in eumenorrheic women,” discusses the effects of estrogen and progesterone on metabolism, and provides information that can be applied by athletes and non-athletes alike in the new year. Dr. Emily Caruso summarized the article while taking the FACTS elective on fertility awareness and women’s health.
Introduction
Many female athletes may notice their exercise performance seems to vary from week to week. For instance, this week’s two-mile run might have been much harder and slower than last week’s five-mile run. Although various factors likely contribute to such differences in performance, the effect of ovarian hormones on exercise metabolism warrants further exploration.
Ovarian hormones fluctuate throughout the menstrual cycle. Progesterone is at its lowest concentration in the first half of the cycle, the follicular phase. A surge of estrogen ensues late in the follicular phase, just before ovulation and the start of the luteal phase. At this point, progesterone and estrogen both begin to rise and reach the highest estrogen/progesterone (E/P) ratio during the mid-luteal phase. While the primary roles of estrogen and progesterone are reproductive, they also influence many other physiologic processes, including those involved in exercise metabolism.
Exercise Capacity & Performance
Numerous studies have examined the effects of ovarian hormones on exercise performance in short-duration, high-intensity interval training (HIIT) workouts. Some evidence shows performance in all out sprints may be best during menstruation, but other studies show the menstrual phase only impacts performance occasionally. Of note, progesterone increases respiratory drive during the luteal phase and lowers lactate accumulation, which may affect performance during HIIT exercises. Endurance capacity improves immensely with increasing estrogen levels, according to studies of time to exhaustion at submaximal exercise intensity. Time to exhaustion is doubled in the mid-luteal phase when E/P ratios are higher, as compared with the mid-follicular phase. This coincides with lower blood lactate levels in the mid-luteal phase. [2]
“Endurance capacity improves immensely with increasing estrogen levels.”
Exercise performance was measured with time trials during different phases of the menstrual cycle. Researchers Oosthyuse et al. found that estrogen promotes carbohydrate use through contraction-stimulated glucose uptake and hepatic glycogenolysis, so performance without carbohydrate supplementation was improved during the mid-luteal phase. [1] Estrogen also promotes fat-use while sparing glycogen stores, which is ideal for performance in ultra-endurance events. When using carbohydrate supplements during HIIT exercises, glucose metabolism was improved in all phases, making carbohydrates the fuel of choice for these workouts.
Carbohydrate Metabolism
Increased estrogen, relative to progesterone concentrations during the luteal phase, influences glucose uptake, glucose availability, and glycogen storage during exercise. Estrogen promotes insulin sensitivity, and therefore increases glucose utilization. It also increases the enzyme muscle glycogen synthase’s production of glycogen in skeletal muscles. Early in exercise, estrogen increases hepatic glycogen use for more glucose availability and uptake into type I, slow-twitch skeletal muscle fibers. Late in exercise, estrogen promotes hepatic glycogen sparing, which ensures adequate glycogen availability after a prolonged period of time. The propensity to spare muscle glycogen during the luteal phase leads to improved endurance performance.
Fat Metabolism
Estrogen has tissue-specific effects on lipid metabolism. In the liver and skeletal muscles, estrogen increases the activity of lipoprotein lipase (LPL), leaving more fatty acids available to use for energy. In adipose tissue, estrogen suppresses LPL activity, causing less uptake and storage of triglycerides in adipocytes. In this way, estrogen helps redistribute lipids from adipose to skeletal muscle. Estrogen also promotes leanness and decreases the size of adipocytes by stimulating lipolysis and suppressing lipogenesis. Research has found that more estrogen receptors are expressed in endurance athletes.
“Estrogen also promotes leanness and decreases the size of adipocytes by stimulating lipolysis and suppressing lipogenesis.”
Protein Metabolism
Studies indicate that ovarian hormones support the maintenance of normal protein turnover. Progesterone promotes protein oxidation, while estrogen antagonizes it. For this reason, further studies must be conducted to determine the extent to which dietary protein requirements change throughout the menstrual cycle. It can be assumed that dietary protein needs to be supplemented during the luteal phase when there is more circulating progesterone, but more research is needed in this area.
Discussion
In general, estrogen and progesterone have opposing influences on carbohydrate, lipid, and protein metabolism. The extent of their effects varies based on the menstrual phase and relative hormone concentrations. A greater E/P ratio improves basal metabolic rate and insulin sensitivity, regulates fat distribution, and promotes performance in sustained exercise. The interplay between the ovarian hormones and exercise metabolism is complex, and more research is warranted to more fully understand their impact. Helping female athletes understand their own kinetics can enhance their training and nutrition and optimize their performance.
“A greater estradiol / progesterone ratio improves basal metabolic rate and insulin sensitivity, regulates fat distribution, and promotes performance in sustained exercise.”
Furthermore, female athletes interested in optimizing their exercise endurance and performance would benefit from learning to chart their cycles using fertility awareness-based methods (FABMs). These methods track biomarkers throughout the different phases of the cycle. By using methods such as the Creighton Model, the Marquette Model or FEMM, among others, they would gain day-to-day awareness of their individual hormonal fluctuations in each phase of the cycle and learn to identify physical signs of ovulation, an important marker of health and vitality. Tracking the female cycle using FABMs should become a standard practice for female athletes.
Sources
[1] Oosthuyse T, Bosch AN. The effect of the menstrual cycle on exercise metabolism: implications for exercise performance in eumenorrhoeic women. Sports Med. 2010;40(3):207-227. doi:10.2165/11317090-000000000-00000.
[2] Jurkowski JEH, Jones NL, Toews CJ, et al. Effects of menstrual cycle on blood lactate, O2 delivery, and performance during exercise. J Appl Physiol. 1981;51:1439-99.
ABOUT THE AUTHOR
Emily Caruso, DO
Emily Caruso, DO, is a family medicine resident at Jamaica Hospital Medical Center in Queens, New York. She wrote this summary as a fourth-year medical student at Lake Erie College of Osteopathic Medicine – Bradenton campus. Dr. Caruso plans to complete the Creighton Model medical consultant training and hopes to bring awareness about FABMs to both physicians and patients.
