Estrogen Effects

Dr. Marieta Buse BSC ND & Dr. Katherine Ahokas BSc ND CISSN

Estrogen is one of the primary hormones crucial for sexual and reproductive development in women. Within the medical community, this hormone is well known to improve bone mass and density. However, scientific literature has recently explored the effects of estrogen on muscle, tendons and ligaments. This research is complex to conduct because many hormones – beyond just estrogen – must be assessed as to determine the cause and effect relationships between the menstrual cycle, exercise and injuries1,2. In this article, you will find 3 main take-aways from the newest research!

#1 Estrogen is Necessary for Optimal Performance and Injury Prevention

Firstly, estrogen – like any hormone – must be at an optimal level: not too high nor too low. In fact, this hormone must also be at certain levels during specific points of the menstrual cycle. Estrogen is part of your intricate endocrine system, which is in charge of ensuring all sorts of hormones in the body are secreted in the right amounts at the right times in relation to each other. Moreover, this endocrine system responds differently to life events in women, such as puberty, pregnancy, and menopause, by altering levels of many hormones, including estrogen4.

Interestingly, female hormones, like estrogen, improve muscle mass and, consequently, strength3. When athletes are training and performing in their sport, muscle breaks down as a result of the forces applied. Estrogen counteracts loss of muscle mass by decreasing muscle degeneration4. In addition, estrogen increases collagen within ligaments and tendons3,5, which is crucial for the strength of these structures, which ultimately support joints.

#2 Too Much Estrogen Can Decrease Performance and Lead to Injury

While testosterone can only reach abnormally high levels through steroid use, estrogens can reach high levels in many different ways4. In particular, the intake of birth control pills, specific foods and/or toxins contributes significantly to abnormally high levels of estrogen. When estrogen reaches levels that are too high, athletes can run into significant problems.

Not only do high levels of estrogen decrease power, but also overall performance3. At the same, high levels of estrogen increase the laxity of joints1,4,5, which makes the athlete more prone to ligament injuries3. Ensuring your joints are healthy has significant merit, given that injuries contribute to more than 70% of the time athletes spend away from training6.

#3 Your Menstrual Cycle Can Support Your Performance

The natural menstrual cycle is usually 28 days. Your cycle starts with the first day of your period, which lasts 5 days in most women. Estrogen is at its lowest level here. Ovulation, on the other hand, is typically halfway through the cycle. Estrogen increases after menses and peaks on this ovulation day. This hormone will peak a second time one week after ovulation. Estrogen then declines until the next period.

This cycle can be synched with training to theoretically optimize performance. Firstly, because estrogen is at its lowest, training during the period should focus on lighter conditioning at the gym and general athletic skills8. Furthermore, the highest peak of estrogen around ovulation provides the most benefit to strength training2,8,9. Women can then take advantage of the second peak of estrogen after ovulation by focusing on resistance and power training8,9,10. Lastly, to reduce risk of injury at the end of the cycle, athletes can focus on tissue regeneration using methods of recovery8.

Last Take-Aways

As discussed in the RED-S article (, athletic performance requires a multi-systems approach to sports medicine and injury prevention. If you are looking to optimize performance, your support team needs to include not only coaches who know your sport but also medical practitioners who know the intricacies of the body. Ultimately, optimization requires turning the right key to unlock your full performance potential. Female hormones are one way within a multi-systems approach to reach an athlete’s full potential.

1 Burgess KE, Pearson SJ, and Onambélé GL. (2010) Patellar tendon properties with fluctuating menstrual cycle hormones. J Strength Cond Res. 24:2088–95.

2 Frankovich RJ and Lebrun CM. (2000) Menstrual cycle, contraception, and performance. Clin Sports Med. 19:251–71.

3 Chidi-Ogbolu N and Baar K. (2019) Effect of estrogen on musculoskeletal performance and injury risk. Front Physiol. 9:1834.

4 Hansen M. (2018) Female hormones: do they influence muscle and tendon protein metabolism? Proc Nutr Soc. 77(1):32-41.

5 Hansen M and Kjaer M. (2016) Sex Hormones and Tendon. Adv Exp Med Biol. 920:139-49.

6 Baar K. (2017) Minimizing Injury and Maximizing Return to Play: Lessons from Engineered Ligaments. Sports Med. 47(1):5-11.

7 Janse de Jonge XA, Boot CR, Thom JM, et al. (2001) The influence of menstrual cycle phase on skeletal muscle contractile characteristics in humans. J Physiol. 530:161–66.

8 Reilly T. (2000) The menstrual cycle and human performance: An overview. Biol Rhythm Res. 31:29–40.

9 Janse de Jonge XA, Boot CR, Thom JM, et al. (2001) The influence of menstrual cycle phase on skeletal muscle contractile characteristics in humans. J Physiol. 530:161–66.

10 Phillips SK, Sanderson AG, Birch K, et al. (1996) Changes in maximal voluntary force of human adductor pollicis muscle during the menstrual cycle. J Physiol. 496:551–7.

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