Scientists Have Discovered A Surprising Relationship Between Estrogen and Exercise - Women's Health

Scientists Have Discovered A Surprising Relationship Between Estrogen and Exercise

A study in mice has led researchers to further explore how hormones influence the brain and motivate the body to move, with women often becoming inactive after menopause, when estrogen fades.

In recent years, the impact of hormones on exercise has come to be a major topic of conversation around sport, exercise and female athletes especially. To ignore hormones when it comes to female athletes and training is to ignore vital opportunities for increased intensity and periods of rest, as the body adapts to hormone production. In a 2016 poolside interview, Olympic Bronze medal swimmer Fu Yuanhui opened up about how her period affected her performance at the Olympic Games, something that had rarely been spoken about in women’s sport of that level. Now, female athletes are speaking publicly about the impact of the menstrual cycle on performance, with scientific studies further illustrating how hormones can lead to different outcomes in training. 

Since a 1924 study involving rats, scientists have known that female mammals tend to be most physically active just before ovulation, which also coincides with when they are most sexually receptive. Researchers have since speculated that such a shift is down to estrogen, which acts as a driving factor in this behaviour. 

For Holly Ingraham, the Herzstein Endowed Professor of Physiology at the University of California, she wanted to look at how estrogen shapes genetic activity in the brain and what this means for exercise. Studies were conducted on healthy adult female mice, with some having their estrogen uptake chemically blocked as researchers tracked how much all of the animals moved. It was immediately apparent that those without estrogen became noticeably more sedentary than other females, suggesting that estrogen somehow affects physical activity. 

The study suggests that the timing of exercise could be fine-tuned for women to factor changing hormones. While the study needs to be confirmed in humans, the researchers have strong reason to believe such findings would be seen in women which could help to explain why inactivity is so common for women after menopause. As the New York Times suggests, “Increasing estrogen levels in older women, for instance, might, in theory, encourage more movement, though estrogen replacement therapy remains a complicated subject because of heightened cancer risks and other health concerns.”

As Paul Ansdel, a lecturer in exercise physiology at Northumbria University in England who was not involved in the study but has extensively studied menstruation and physical performance suggests, “This study has significant implications for human research studying the menstrual cycle and hormonal contraceptives and also menopause.” Ansdel added, “We know the importance of exercising in later life for promoting and maintaining health,” going on to add, “so the challenge for us now is to understand the best ways to stay active throughout the major hormonal transition that is menopause.”

Dr Ingraham hopes that such research can now be used to better understand how we move and why, with the intent of making our older years healthier. When it comes to training and your own cycle, several studies have shown that strength training in the follicular phase resulted in higher increases in muscle strength compared to training in the luteal phase, while women are 3 to 6 times more likely than men to have injuries to their ACL, with the risk highest in the days leading up to ovulation when estrogen is high. Ultimately, keeping track of your cycle is important and can do wonders for your athletic performance but more importantly, understanding it. It’s important to not judge the results of your training on your performance as in some instances, hormones play a significant part. 

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