Midlife, Muscle, and the 5 Myths We’ve Been Told
What no one is telling women about their midlife muscle
I saw an influencer’s Instagram post about a woman doing F-45 workouts. Because she isn’t building muscle due to a lack of progressive overload, this influencer frowned upon this exercise.
This prominent message is that if you’re not building muscle, the exercise at hand is not at all beneficial to muscle.
This is a complete lie. Not an on-purpose type of lie, but one that is missing key information.
No doubt, muscle is having its day as the saving grace not only for midlife women, but for longevity.
We’re told—like the Instagram post — that because we are losing muscle mass every decade, we need to build muscle with strength training.
Yeah, that’s part of it, but there’s more to it than that. Knowing the whole story can help women avoid common mistakes, make smart decisions, and live healthier lives.
But first, let’s start with some basics.
Muscle 101
The human body has over 600 skeletal muscles, consisting of 40% of the body’s weight. The name “skeletal muscle” comes from the muscle’s attachment to bone and its role in all our purposeful movement.
Skeletal muscle works with bones and joints to create levers for the everyday movement. They contain fibers that give it a striated appearance and perform specific jobs.
Type 1 fibers are slow and precise in how they contract and are resistant to fatigue because they use aerobic respiration. They are also important for endurance and proper poster control.
Type 2 fibers are stronger and faster than type 1, but they do not have the same endurance.
Hormones aid the maintenance and growth of skeletal muscle, including growth hormone, insulin, testosterone and estrogen.
After 30, with biological aging and changes in growth hormone, muscle mass is at risk for declining, something that speeds up after 50 and with menopause. Aging also causes a greater loss of type 2 fibers.
There’s more to the story
What I’ve just mentioned is nothing new to most health-conscious women.
Women also need to know that blood vessels nourish and support muscle fibers, motor neurons innervate them, satellite (stem) cells repair and regenerate them, and mitochondria provide them with energy in the form of ATP.
Compromising one or more of these factors, also compromises muscle health.
Take the difference between men and women. Although both estrogen and testosterone play important roles in muscle maintenance, testosterone plays a larger role in hypertrophy.
Before puberty, males and females have about 80% lean tissue. After puberty, boys increase lean mass to about 90% while girls add more fat resulting in 70-75% lean tissue.
Because men have 20 times the testosterone than women, they have higher levels of skeletal muscle and strength. Biopsies taken since the 70s show that men also have more type 2 muscle fibers than women.
Women have a higher percentage of type 1 fibers and muscle endurance, which makes them better at resisting fatigue.
Even though building muscle is a well-known health hack, guys having more muscle doesn’t equate to better heart health or blood sugar when they’re young.
Why is that?
Because it’s not just about muscle quantity but quality. These 5 myths help explain it.
Myth #1: Muscles = Strength
When people talk about muscles, they often focus only on muscle tissue. But did you know the nervous system is just as important as the muscle tissue itself?
When you lift weights, your body doesn’t just change your muscles—it also changes how your nerves work. Specifically, it improves how motor units work.
A motor unit includes a nerve cell, its long fiber (called an axon), and the muscle fibers it controls or innervates. One nerve can control several muscle fibers at once, and when it sends a signal, all those fibers in the motor unit contract together.
Imagine a light switch connected to several light bulbs. The switch is like the motor neuron, and the light bulbs are like the muscle fibers. When you flip the switch (send a signal from the neuron), all the bulbs light up at the same time (all the muscle fibers contract together).
Different switches (motor neurons) control different bulbs (motor units), and as you train, your body gets better at flipping the right switches more quickly and efficiently.
It’s pretty amazing when you think about it—your brain and spinal cord are just as important as your muscles for getting stronger.
For muscles to produce forces, central nervous system has to recruit them.
- Alix-Fages, Eur J Appl Physiol, 2022
Myth #2. Heavy lifting and protein are all that muscles need
While challenging muscles with weights and ensuring adequate protein are important, there is something vital that’s missing.
Unlike other tissues, muscles cells don’t completely replace themselves. Instead, special stem cells called satellite cells repair them. Satellite cells fuse in new fibers, repairing damage from exercise and stimulating muscle protein synthesis.
With biological aging and lower level of estrogen (Aging Pause), the satellite cell pool decreases, impairing regeneration of muscle.
Luckily there are many things we can do, starting off with both strength and aerobic exercise which stimulates muscles regeneration capacity.
Another vital aspect is the One Health Principle, which means keeping infla-stress down while maximizing nitric oxide (NO).
This matters because NO is a key messenger for satellite cells.
Additionally, contracting muscles in a variety of ways helps them secrete potent and anti-inflammatory myokines, which communicate with other organs like the brain, bone and fat tissue, enhancing their function.
In short, a variety of factors - not just lifting and protein - help us regenerate and repair muscle as we age. More on this in a future post.
Myth #3: Cardio breaks down muscle
We are told that strength training is the only way to build muscle, and even that cardio can hurt this process.
As I mention in my Case for Cardio post, “Although resistance exercise is the gold standard for increasing strength and skeletal muscle mass, aerobic exercise plays a complementary role.”
One vital way is ramping up mitochondria, the powerhouse of cells. Mitochondrial function can decrease with age, but aerobic exercise increases demand, keeping mitochondria in working order.
Researchers found that older lifelong endurance exercisers had higher mitochondrial volume and connectivity than their sedentary and less-trained peers.
Another perk of aerobic exercise is angiogenesis, which is the formation of new capillaries that reach muscle, enhancing microvascular health.
Last is aerobic exercise increases blood flow and V02 max, stimulating anabolic pathways via the more efficient delivery of amino acids, oxygen, and nutrients to muscle.
Myth #4. Quality matters more than quantity
Researchers have pointed out that muscle mass alone is not always responsible for muscle function, strength, and mobility. And the answer has to do with a key determinant of muscle quality, which is how dense muscles are.
When fat infiltrates muscle, it is called intermuscular fat infiltration (IMAT), which reduces muscle quality.
IMAT is when there is lipid storage deep in the muscle fascia, which becomes visible in muscle fibers and adipocytes.
Aging and inactivity increase fat deposition in muscle, increasing risk of poor mobility, reduced muscle function, balance problems and falls, decreased strength, insulin resistance/metabolic disease, and microvascular disease, which is higher in women. women.
READ: Women Have Been Mislead About Heart Disease
In a study of 1,219 women aged 75 and older, researchers found that having better muscle quality—meaning less fat in the muscles—was linked to better physical function independent of muscle mass. Those with high muscle quality were 26% less likely to have problems with movement and daily activities.
Muscle quality is increasingly being recognised as an important determinant of muscle function. Muscle size, fibre type, architecture, aerobic capacity, intermuscular adipose tissue, fibrosis and neuromuscular activation all potentially contribute to muscle quality.
McGregor, Longevity and Healthspan, 2014
Myth #5. Large muscle groups rule
While we’re being told to work our large muscles, we forget about other hidden muscles, including stabilizer muscles, breathing muscles, airway muscles and pelvic floor found deeper within the body.
Exercising these muscles may not build muscle mass or show up as toned muscles, but they are vital for health as we age.
Whether that’s avoiding injury and falls by strengthening stabilizer muscles or keeping inflammation down with a strong diaphragm and intercostal muscles, we undoubtedly benefit from working all our muscles, large and small.
The Midlife Muscle Series
This can be overwhelming, I know, which is why I’m going to dig into each of these areas in different posts for my midlife muscle series.
When I’m done, you’ll understand which exercises, and nutrition and lifestyle strategies help to keep your midlife muscle in tiptop shape.
It’s saddens me to see women giving up an exercise they love because they fear it will hurt their muscle.
It's time to challenge the outdated fitness advice that tells women there's only one "right" way to exercise. Muscle health is about more than just building muscle—it's about quality, function, and strength.
Please let me know if you have questions or topics you want me to cover.
Finally! An article dispelling the muscle myths! Between poor sleep and achy joints, some days it's hard enough to even make it to gym or get out for a walk, let alone worry about whether or not I'm actually exercising correctly.
Thank you for this! I've been trying to add more strength, heavy lifting, into my routine. But I LOVE pilates and barre class and have been trying to understand if I"m wasting my time with these. I won't give them up bc I feel better after doing them, my muscles get to the point of fatigue in classes too. I did see a weight lifting influencer say such exercise is pointless for muscle growth. It's confusing out there!