Most of us have heard about what happens when estrogen levels decrease after menopause in women. For example, women have an increased risk of developing osteoporosis and bone fractures as a result, and low estrogen levels can also cause hot flashes, night sweats, heart palpitations, headaches, and insomnia. But many might not know the link between menopause and muscles.
Estrogen and Our Muscles
We know that menopause is associated with a decline in estrogen, and that creates a decrease in muscle mass and strength. Low physical activity and low protein in the diet contribute to sarcopenia (loss of muscle mass) and the loss of strength after menopause too.
A new study published in Cell Reports shows how estrogen levels play a key role in muscle function, maintenance and as a result, overall strength. The researchers found that the loss of estrogen leads to a 30 to 60 percent drop in muscle stem cell numbers across five different muscles. Muscle stem cells are also known as “satellite cells”. These cells are usually in a dormant stage until they are called upon to help repair an “injury” when a muscle fiber is stressed, say, during weight lifting. The new study shows that the loss of estradiol (a well-known female sex hormone produced by the ovaries) has a negative effect on our very important satellite cells.
This is especially relevant in a strength-training program, as muscle “injury” or stress is what happens when we lift weights. Building strength is our body’s response to that stress or “injury.” We now know that how muscles rebuild themselves could be compromised in women after menopause.
It’s something to be aware of when we feel like we are doing the same amount of work without the same result after menopause.
Hormones and Muscle Recovery
As we age, estradiol decreases and that having less of that hormone “reduces skeletal muscles mass and force generation in women,” according to the study summary. This study proves that hormones help in “overall muscle regenerative capacity” also known as recovery. So now we see how estradiol is essential, too, for recovery because of its role in muscle stem cell maintenance and function.
An Alternative to Hormone Replacement Therapy
It has long been known that estrogen replacement therapy can help maintain muscle health. But for those who are afraid of increased cancer risks due to hormone replacement therapy (HRT), the researchers also showed that a new class of drug could interact with estrogen receptors and create the same outcome as estradiol in preventing the muscle stem cell decline after menopause.
Before this research study, the majority of studies focused on men, comparing muscle from old men to young men. But in this research study, they studied the satellite cells in women during the transition of menopause, taking biopsies from the same women at peri- and post-menopause. Finally, research that helps us understand how menopause affects muscle strength.
The study in Cell Reports was published by authors Down Lowe, PhD, Professor in the Department of Rehabilitation Medicine, Division of Physical Therapy and Rehabilitation Science Graduate Program, University of Minnesota Medical School and Michael Kyba, PhD, Professor of Pediatrics and Carrie Ramey/CCRF Endowed Professor in Pediatric Cancer Research, Department of Pediatrics, Division of Blood and Marrow Transplantation, University of Minnesota Medical School.