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Writer's pictureDr Em Wong

The Secret Life of Muscles



Robust. Mixed media on paper. Discovery Bay, 2024.

Muscles are so integral to our daily lives that we don’t even think of them as being separate from our limbs. We know that muscles are required for us to walk, run and climb, as well as to carry, twist, and lift things. But most of us will only pay attention to muscles when doing focused exercises like stretching hamstrings, or when they are injured or fail to perform as expected.  








The rise and decline of muscles over the lifespan


You probably know that weight-bearing and resistance exercises can help to preserve bone density as you get older, slowing the process of bone loss seen in osteoporosis. But did you know that muscle loss follows a similar trajectory of loss over the course of natural ageing?


Fig A - Sarcopenia: revised European consensus on definition and diagnosis (Age Ageing, 2019 Jan 1;48(1): 16-31)

It turns out that like bone, our muscle mass peaks at around the age of 30. And then muscle tissue is lost through an extremely gradual process called sarcopenia. 


Sarcopenia is a normal and natural part of the life cycle for humans—and even some mammals. Most people will lose about half a pound of muscle per year, which means that by the age of 60, we will have lost about 15lbs of muscle mass. Much of that muscle is replaced by fat or adipose tissue—shifting our body composition towards conditions that favour the development of diabetes, high blood pressure, stroke, and heart disease. 


We are able to retain more muscle mass when we are more physically active

The good news is that you can absolutely prevent this decline. 


In fact, the reason that some people are able to retain more muscle mass is because they are, you guessed it…more physically active. Whether they have been cleaning the house, gardening or going to the gym, it all helps to maintain muscle mass and strength.


The bad news is that sarcopenia is often accelerated by periods of hospitalization, protein malnutrition, or immobility (due to injury or sedentary lifestyle). The average elder can lose more than 50% of their lean muscle mass by their 80th birthday. Even short term conditions—like a sprained ankle or stomach flu—can accelerate muscle loss. 


Fig B - Sarcopenia (Image credit: https://mobile.hksh.com/en/physio-our-services/what-is-sarcopenia)

So it becomes imperative to build and maintain a strong reserve capacity of muscle to draw on when needed. And while it’s possible to proactively build back muscle through strength training, changes in hormones and growth factors makes it harder and harder to do so as we get older. 


Just as with retirement savings, the sooner that you start investing (in your lean muscle mass), the better your chances of building and maintaining your strength and health for the future.


Muscles as brain and hormone modulators


We know that movement is good for both current cognitive function, as well as protecting against brain ageing diseases—like dementia or Parkinson’s disease. Many such benefits are attributable to global physiological changes like improved blood flow, lowered blood pressure, and better sleep. But many of the positive impacts of exercise on brain health are actually directly attributable to muscles. 


Fig C - Your muscles’ secret superpowers. (Canva graphic) 

Muscle tissues have a host of invisible superpowers which include:


  • Stimulating neural connections through movement, thereby activating neurochemical signaling in moving, sensing, and coordinating parts of the brain

  • Activating storage and metabolism of sugars and fats, which boosts crucial energy management functions of the pancreas and liver

  • Enhancing energy production through mitochondrial activation and proliferation

  • Facilitating active circulation of blood in our veins, which regulates fluid balance and removal of metabolic byproducts

  • Inducing the release of feel-good chemicals like endorphins and hormones like dopamine that reward and motivate us to keep moving


When we exercise, muscles produce multiple signaling molecules called myokines that communicate with the brain, pancreas, liver, and other organ systems in a rich dialogue that serves to regulate inflammation, reduce insulin resistance, and enhance immune function. 


Myokines are also known as “hope molecules,” because they have been shown to protect against mood disorders

Perhaps the best known myokine is irisin, which has been shown to reduce inflammation and regulate our metabolism. 


Irisin can also boost levels of brain derived neurotrophic factor (or BDNF), which is thought to act like a kind of Miracle-Gro for brain cells, because it helps to maintain brain cell mass and function, and to promote neuroplasticity. 


Myokines are also known as “hope molecules” because they have been shown to protect against mood disorders like depression and anxiety—known risk factors for future dementia.


Through the process of sarcopenia, we are losing more and more of our muscles' invisible superpowers as we grow older. In fact, it’s fair to say that our muscles are key to being able to halt or even reverse the drift and decline of passive ageing. 


Lean muscle strength has been linked to lower risk for cardiovascular disease and correlates with improved cognitive function. Muscles don’t need to be bulky, they just need to be strong.   


Strengthen to age powerfully


Sometimes when we haven’t seen our elder relatives or friends in a while, it can seem like they are noticeably shrinking. Actually, this process is happening constantly, but changes tend to be so subtle that we don’t notice it in ourselves or our partners. We all lose a few millimeters in height as our vertebrae and intervertebral discs age, but visible ageing is more often due to postural changes.   


Postural changes aren’t just unattractive, they can affect our balance, making it more likely for us to fall as we get older. For example, most of us tend to spend too much time leaning forward to peer at our computers or phones. This leads to stooped necks and rounded shoulders. 


Muscles are key to halting (or even reversing) the drift and decline of passive ageing

Muscles in the chest and neck get too tight and shorten, and underused muscles in the back get overly stretched out and can even atrophy or die. That’s why postural imbalances become more and more difficult to correct with advancing years.


Working to build strength not only corrects postural imbalance, but also improves your speed and agility, so that you can catch yourself on uneven terrain.



Fig D - Postural imbalance. (Image credit: Canva)

Another aspect of modern life that contributes to poor balance comes from sitting and wearing shoes. 


We tend to lose the use of all those tiny muscles in our feet and ankles when they are cooped up in shoes, and our backs and bottoms can get lazy from too much sitting. 


What would it be like to challenge yourself to take a 5-10 min break in your work day to do a couple sets of ankle lifts or air squats during the day? 


We don’t have to allow our muscles to melt away gradually like glaciers. We actually have the ability to work on slowing or even reversing the course of Nature. 


It’s work that no one else can do for us. We must each choose to invest the effort for ourselves individually.  


Strength training becomes an ever more important component of exercise as we age. Resistance exercises build physical strength, stamina and stability, plus we get to gain back the powerful metabolic and physiologic benefits that accrue with more lean muscle.


Dr Em coaching tips


The muscles of our feet and legs work together with our vision and position sense, inner ear balance, and spatial sensing apparatus. Some simple home balance assessments can help us to appreciate how many moving parts are required for balance: 


1. Start by holding on to a countertop at home, simply standing in your bare feet with your feet together. Close your eyes and let go of the countertop for at least 30 seconds. 


  • On a scale of 1 to 10, how stable or wobbly do you feel (where 1 is “I’m gonna fall” and 10 is “Rock solid”)?


2. Next, try holding on while placing your feet in a tandem heel-to-toe stance. If that feels comfortable, close your eyes while holding on and then try letting go of the countertop for 10, 20, or 30 seconds. 

  • Any wobbliness or shaking is a good sign that your muscles are working for you.

  • If you feel unsteady at this stage, keep practicing this exercise for at least 5-10 mins daily for one week before moving on. 


3. Stand on one foot while holding on, and then let go, staying close to the countertop (in case you need to grab hold). 

  • It’s a good idea to keep your eyes open and focused on a point on the wall in front of you the entire time for this one. 

  • Notice any differences between the right and left foot.




 


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