Larger muscles or muscle mass improves our chances of living longer, happier lives.  Muscle mass correlates with longevity.  Muscle mass correlates with improved recovery following injury or surgery.  Larger muscle mass improves our metabolic machinery which decreases the burden of chronic diseases like obesity, hyperinsulinemia, and type 2 diabetes.

It is time for us to prioritize activities and optimize our lifestyle to improve our quality of life, and longevity.  The more targeted and easier these discussions are to understand, the better the chance that you might adopt lifestyle modifications that could directly impact your chance of living a longer, healthier life, more active life.  No one wants to spend their last decade as a frail shell of the person they used to be.  Your actions today will influence your risk of frailty in the future.  

Why is an Orthopedic Surgeon talking about muscle mass? 

As a middle-aged Orthopedic Surgeon and Sports Medicine specialist, I have spent the last few years combing through an enormous amount of data.  I have done so to optimize my own lifestyle strategies, and to prioritize my health.  2019 witnessed a distinct change to the subject matters I have chosen to write about on this blog.  I have done so so that you may benefit from everything that I am learning along the way.  Think of me as a primary care sports doc. 

I want to emphasize strategies that you can adopt now to lessen the chances that you will suffer from many chronic diseases and an early demise.  I have plenty of articles on this site that go into detail about meniscus tears, rotator cuff injuries, and other maladies that affect us… but my goal now is to improve your understanding of simple life-prolonging strategies that are presented in a simple actionable manner.  Hopefully, that improves your chance of success.  I am in the best shape of my life… I would love to hear you say the same thing.  

The online healthcare world is loud, confusing and sometimes wrong

In many online circles, there is a multitude of people who are discussing approaches to improve our chances of living longer, healthier lives. We are all too easily fooled into drinking alkaline water, trying highly restrictive and unsustainable diets,  or trying supplements to improve our strength and lifespan.  Yes, a longer lifespan, and a healthier life or improved healthspan is achievable. We can achieve these things with very simple straightforward advice, backed by science. 

Over the last year, I have spent a lot of time talking about the importance of proper sleep, proper exercise, and a proper diet.  As we have discussed, nearly 40% of dementia cases each year are likely preventable if we improve our sleep, and exercise regimen.  And we are not talking about drastic changes.  Walking even 5000 steps per day matters.  Sleeping 7+ hours a night and bodyweight resistance exercise is quite often all you need.  

We are tethered to our phones. We are rushing to get the kids off to this activity or that activity.  The ultra-processed foods which are omnipresent and eaten to enable our busy lifestyle are all contributing to the fact that for the first time in history we are not living longer than the generation before us.  These online folks get into very heated, very detailed discussions about their preferred diets, exercise patterns, and sleep patterns.  Their vocal, paternalistic, and aggressive manner turns many people off.  There are alternatives to the noise.  

How does our muscle mass affect our health?

Muscle tissue is highly metabolic.  That means that your muscles are metabolic machines that are always looking to burn fuel. By burning glucose or fat, our muscle decreases the caloric burden that our other tissues need to contend with.  The larger and more active your muscles are the fewer fatty acids and glucose molecules you have floating around inside of you.  The fewer energy precursors floating around our blood,  the less the chances are that those molecules will contribute to the visceral fat burden you have.  Visceral fat is not only unsightly… it can directly contribute to illness.  

Visceral fat is the fat around your belly.  It is also the fat around the organs inside your body.  Visceral fat, as opposed to subcutaneous fat which is the fat under your skin, is also highly metabolically active.  But the metabolic activity of visceral fat produces far more of an inflammatory and toxic cadre of molecules that lead to chronic disease states.  Visceral fat does than simply store excess energy. Visceral fat cells produce inflammatory markers, such as IL-6, and TNF-α.  These substances increase your risk of chronic diseases associated with low-grade chronic inflammation. For example, heart disease requires both elevated LDL cholesterol and chronic inflammation to cause a block in your arteries.  As we discussed here before, chronic low-grade inflammation also increases your risk of developing dementia.

It should now be fairly clear why we want to optimize for an increase in our muscle mass over visceral fat.  The larger our muscles are the more overall metabolic activity is taking place.  Muscle burns energy and does not pollute our bloodstream with toxic inflammatory chemicals.  So the more muscle tissue you have the more energy it will burn. That means you will burn more calories simply by having larger muscles.  So to optimize our health and longevity we would prefer to have more metabolically active muscle than active visceral fat.

How much weight should I use and how many reps should I do? 

For a deeper understanding of why we should lift a certain number of repetitions, etc just keep on reading.  For a better understanding and a list of the 6 reasons why you should exercise your legs today, just skip this next section :-). 

This is a very interesting area to explore.  There is a lot of confusion, even in the scientific world with respect to this topic.  It turns out that “time under tension” might be a very important parameter when it comes to increasing the amount of new muscle protein that your body manufactures.  Consider this… your one-rep maximum (1RM) is the highest amount of weight that you could lift only once.  Many papers discuss lifting weights at 70% of your 1RM- and doing approximately 5-7 reps until volitional failure.  That might not be the best way to go about exercising for muscle growth and sarcopenia prevention or treatment. 

Time under tension is how long your muscle is being exposed to a heavy weight.  So if it took 5 seconds to push your 1RM weight then your muscles were under tension for only 5 seconds.  If you exercised with a weight that is equivalent to 30% of your 1RM and was able to do 20 reps until volitional failure and it took 5 seconds to do each rep then your muscles were under tension for significantly longer than 1 rep at your maximum weight- despite the fact that both exercises were done to volitional failure.  So… doing less weight and more reps increase your time under tension, probably decreases your risk of injury, adds an aerobic component to the exercise regimen, and results in higher and more longstanding muscle protein synthesis.

Diving deeper, Dr. Stuart Phillips has found that manipulating different resistance exercise variables impacts both the acute and chronic anabolic (muscle building) response. For example, when young, resistance-trained (recreationally weight-training ≥2 times per week for ≥2 years) men received 20 g of whey protein after exercise, those who lifted with increased time under tensions (12 s per repetition) had elevated muscle protein synthesis (MPS) when compared to a repetition-matched control (2 s per repetition) (Burd et al., 2012). Various experiments on thigh muscles have shown that the group exercising with longer time under tension had increased muscle activity, and presumably muscle fatigue, toward the end of set completion (Burd et al., 2012).

Dr. Phillips speculates that the “elevated MPS response to the longer time under tension is a result of increased motor unit recruitment which may be linked to muscle damage/remodeling (Proske and Morgan, 2001).” What he is referring to is how many of your muscle cells are actually firing, or active to help you resist the load that you are working out with. If you are lifting a lighter weight you do not need all the different muscle fibers to fire or be active at one time.  By increasing the time under tension you will be recruiting more muscle cells to become active as the muscle fibers which became active first start to become fatigued.   I hope that makes sense.  The more muscle cells you have working, the more muscle protein you will make, the larger your muscles will be.  

The above argument is one of the reasons why we recommend weight lifting until volitional failure.  If you simply do 10 repetitions of a light weight that you find easy to lift, then you have not recruited many muscle cells/fibers to participate in your efforts.  By lifting to failure you will recruit more muscle cells to contract or fire.  That will in turn lead to more gains in muscle mass.  The key issue here is the concept that you do not need to lift heavy weights just a few times to failure.  That thought scares many people.  Instead, you can lift slightly lighter weights with more repetitions—as long as you go to failure.  

People like counting the number of repetitions they do.  The reps that are easy shouldn’t be counted… you count the ones that are challenging.  Challenge yourself.  Do so wisely and with training to minimize your risk of injury.  Keep reading to get to the 6 reasons why you should exercise your legs today.  

Dr. Phillips has also reported that when recreationally-active participants performed leg extensions at either 30 or 90% of their one-repetition max (1RM) to contractile failure there was an equal increase in new muscle protein synthesis (Burd et al., 2010).

Therefore,  it appears that reaching volitional failure is required for maximizing muscle protein synthesis and thus muscle growth. This can be achieved regardless of the amount of weight that you are lifting.  By manipulating the time under tension or the amount that you lift you can reach a point of contractile failure by increasing muscle fatigue and thus enhancing the rate of motor unit recruitment. 

Dr. Phillips concludes by saying that in contrast to current recommendations (American College of Sports Medicine, 2009), he proposes that “an important variable to consider in regards to the optimization of muscle protein synthesis and the subsequent hypertrophic response is to ensure, regardless of the load lifted, that loads are lifted to the point of contractile failure.” 

6 Reasons Why You Should Exercise Your Legs Today 

1. Which muscles should I prioritize? The muscle you choose to exercise should be those that will have the greatest protective effects.  It’s quite intuitive.  Your leg muscles are larger.  The larger the muscle the more metabolically active it will be.  This will decrease your caloric burden and decrease the amount of energy your other organs and visceral fat need to store.  In addition, exercising your legs will improve your ability to prevent a fall, decrease the chance of injury from a fall, and improve your recovery time after a fall.    
2. Muscle mass matters.  Your muscle mass… or how large your muscles are will directly correlate with longevity.  Muscle mass protects your metabolism, enhances glucose uptake and energy expenditure. That decreases the number of excess calories that our body needs to store as fat. The less visceral fat you have, the lower your risk of developing worsening chronic disease. Hyperinsulinemia is a leading cause of disease in our modern society.  Most of you only consider type 2 diabetes to be a burden.  Hyperinsulinemia or a situation where your body requires more insulin to deal with a certain amount of glucose precedes the presence of type 2 diabetes by 5-10 years.  Therefore, the more muscle mass you have, the more you exercise, the lower the risk of having hyperinsulinemia and progression to type 2 diabetes.  
3. Dementia and Neurocognitive Decline:  Resistance exercise decreases your risk of neurocognitive decline.  Face it, many of us fear dementia more than we fear heart disease.  Neurocognitive decline or dementia is termed type 3 diabetes in some circles.  That is because up to 40-50% of cases of dementia may be due to our lifestyle! Our metabolism and activity level affects many hormones that directly influence the health of our brain.  Exercise induces changes in hormones like growth hormone and Insulin-like growth factor (IGF-1), both of which protect our brain tissue from degenerating.  
4. Improved Strength: This post is not about having bigger legs for looking better.  It is about improving your current quality of life and improving your chance of living a longer, disease-free life.  Improving your strength will decrease the risk of you falling. You will lift your legs better as you propel yourself upstairs, or walk downstairs.  Your confidence will increase as your fear decreases.  This may not sound like a great reason to workout your legs to a 40-something, but you should consider what your life will be like in your 60s and beyond.  Frailty is a very common cause of demise.  We should do everything we can to halt the progression of sarcopenia or age-related muscle loss.  Your future self will thank you.  
5. Decreased risk of injury: Larger muscle mass is not only a friend to your metabolic machinery, it is a protective mechanism for your skeleton.  As we age we also lose our balance more frequently.  In our 40’s and 50’s, we may simply note (or not) that we catch our feet on things more frequently or feel less stable when we stand or move abruptly.  That is also a terrible consequence of the aging process.  This loss of balance and control will ultimately lead to falls as we age further.  Having greater strength and muscle mass will not only limit our fall risk, but it will decrease the risk of injury associated with a fall.  This is not a meaningless issue.  While chronic disease makes us ill and frail, it is the injuries sustained after a fall which ultimately leads to further frailty and untimely demise.  Each fall requires recovery.  With poor strength and low muscle mass, each recovery never returns us back to baseline.  Each fall results in a little more loss of function.  This sets us up for yet another fall, and a vicious cycle ensues. 
6. Improved lipids and cardiovascular health: Many trials over the years have shown the benefits of exercise with regards to our cardiovascular health.  Aerobic and resistance exercise both have a dramatic effect on your cardiovascular risk profile.  Resistance exercise improves your lipid profile and many other determinants of your risk profile for heart disease.  By improving insulin resistance and glucose control you will have less chance of developing type 2 diabetes and other chronic diseases. Those of you who perform leg exercises will have less belly fat or visceral fat.  That will significantly decrease the chronic inflammatory mediators that are flowing through your bloodstream.  That will decrease your risk of hyperinsulinemia, fatty liver, and cardiovascular disease.  People who perform resistance exercise have lower LDLc and ApoB, both of which are likely responsible for atherosclerosis and blockage of your arteries.  Exercise will decrease your triglycerides and increase your HDLs.  We explored how our triglycerides affect your health and well being in a more detailed manner in this post.  

As you can see, exercises that emphasize lower extremity strength and muscle mass can have a significant impact on your current quality of life and your risk of dying prematurely from chronic disease or injuries from a fall.  As part of an overall longevity plan, resistance exercises have an equally important role as proper sleep and a proper diet.  

Of course, meet with your doctor if you are concerned that exercise may be too much for your heart.  Yes, injuries can occur by lifting weights, but the risks of injury are outweighed by the risks to your health of not exercising.  Life is a series of risk: benefit analyses.  Assess your risks and you will likely conclude that exercise should be a part of your normal weekly routine.  

Resistance exercises should be performed three days per week.  A balanced leg exercise program includes hip hinge exercises such as squats and deadlifts.  Before doing them you should make sure that you know how to perform them properly to avoid injury.  Calf raises are critical since the calf is one of the first muscles to succumb to sarcopenia.  Bridges, leg extensions, and leg curls help to round out a balanced leg exercise program.