Muscle Mass Can Predict How You Age: Here’s Why (and How) To Build It

That’s because muscle tissue is in a constant state of turnover. New muscle tissue is generated through muscle protein synthesis (MPS), alongside muscle protein breakdown. As you age, the rate of MPS slows, which makes building new muscle more challenging. So, it takes more concerted effort to stimulate MPS. [5]  

Pro tips:  

2. Hormonal changes impact muscle and bone mass 

Both men and women experience hormonal changes with age that impact the ability to hang on to muscle and bone – together, called lean mass.  

For women, estrogen is a protective hormone. Estrogen levels fluctuate and then decline during perimenopause, which can accelerate age-related muscle and bone loss. [6] 

Men aren’t immune to hormonal changes, either. Testosterone levels, a hormone that helps build muscle, gradually decline with age. So, declining testosterone levels can make maintaining and building muscle more challenging. [7]  

Since hormonal changes make muscle building more challenging, resistance exercises become even more critical in your 40s.  

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3. A slowed metabolism 

The loss of lean mass (muscle and bone) that accompany aging can actually slow your metabolism.  

Because muscle tissue is more metabolically active than fat, individuals with more muscle mass tend to have higher resting energy expenditure, meaning they burn more calories throughout the day (even when not exercising). [8]  

Lean mass isn’t the only thing that impacts metabolism, sex, age, and hormones also influence your resting energy expenditure.  

However, maintaining and building muscle is one of the biggest lifestyle levers you can pull that keeps your metabolism active with age. 

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4. Reduced cardiovascular function 

The heart is also a muscle. It becomes less efficient with age, working harder to circulate blood, oxygen, and nutrients throughout your body. It can make everyday activities feel more tiring than they used to. [9] 

Fortunately, cardiovascular exercise (like walking, running, and biking) can train your heart and improve your cardiovascular fitness. [10]  

Cardiorespiratory fitness (typically measured by VO₂ max, or the maximum amount of oxygen your body can use during intense exercise) is a strong predictor of overall health and longevity. [11] 

A higher VO₂ max means your body is better at delivering and using oxygen, which supports stamina, recovery, and resilience. [11] You can get an estimate of your VO₂ max through certain smartwatches, fitness apps, or more precise lab-based fitness testing. 

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5. Joint stiffness and reduced mobility  

As we age, maintaining mobility (the ability to move freely and easily) becomes increasingly important for quality of life. Reduced mobility can make everyday tasks harder, increase the risk of falls, and limit independence.  

One common contributor to joint stiffness and restricted movement is a change in connective tissue, including fascia — the thin layer of tissue that surrounds muscles, bones, and joints. Over time, fascia can become thicker and less elastic, which may limit your range of motion, reduce blood flow, and slow down recovery. [12] 

Regular physical activity and mobility-focused exercises can help keep joints lubricated and moving well. [13] 

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How strength training can counter these changes 

Incorporating a mix of cardio and strength training can help counter age-related muscle loss. There are numerous researched benefits to adding this type of training to your routine in your 40s and beyond: 

• Improved strength, balance, and endurance: One systematic review and meta-analysis found that exercise programs significantly improved muscle strength, balance, and endurance in people aged 40-65 years. [14]
• Improved bone mineral density: Consistent strength training has been shown to improve bone mineral density, especially in postmenopausal women. [15] A study published in 2023 even found that six weeks of training with dumbbells improved bone mineral content and age-adjusted bone health scores in people in their 60s and 70s.  [16] 
• Metabolic health: Studies show that strength training can help lower blood pressure, improve insulin sensitivity (lowering the risk of type 2 diabetes), and improve the composition of lean mass to fat mass. [17, 18, 19] 
• Reduce the risk for falls: Strength training helps maintain functional independence by preserving or improving strength, power, mobility, and balance. This translates into lower risks of falls, injuries, frailty. [19, 20] 
• Quality of life: A 2023 study reviewed data from 21 studies and 1,610 older adults to see how resistance training impacted muscle strength, mental health, and quality of life. Results showed that there was a significant improvement in social function, depression, and pain. [21] 

How much physical activity do you need?  

Getting the health benefits of exercise doesn’t have to mean spending hours a day at the gym. 

The Physical Activity Guidelines for Americans recommend that all adults get at least 150 minutes of moderate-intensity aerobic (cardio) activity per week or 75 minutes of vigorous-intensity activity per week. [22] 

This includes activities like hiking, jogging, walking, and climbing up and down stairs. 

The guidelines also recommend that all adults participate in muscle-strengthening activities two or more days per week that activate all major muscle groups (including your legs, hips, back, abdomen, chest, shoulders, and arms).  

These activities include bodyweight exercises, weightlifting, carrying heavy groceries, and even some forms of Pilates.  

For older adults, the guidelines also recommend including exercises that improve your balance and coordination, like single-legged movements, to help reduce the risk of falls. 

How to start strength training to build muscle 

So, the question becomes: How do you incorporate, and stay consistent with, this level of physical activity?  

Here’s what the American College of Sports Medicine recommends: [23] 

Check out this article for 10 tips on maintaining a consistent activity regimen that you actually look forward to. 

 Key takeaways   

References