Muscle Matters: The Surprising Key to Longevity, Metabolic and Cognitive Health

Physical strength is linked to healthy aging. Higher cardio-respiratory fitness is linked to greater life expectancy. This means we need to have and maintain strong muscles throughout life if we want to have an enhanced quality of life allowing us to enjoy life to the fullest.

But to think of skeletal muscles as only good for moving our bones is like claiming that the internet’s sole purpose is to share cat videos. This is far from the whole picture.

Even if we are not all body builders our muscles occupy a large part of our bodies, around 40% of our total body weight. Since skeletal muscle plays a large role in our metabolism, heat and blood flow regulation as well as secreting substances that communicate with our immune system and brain, technically it is an organ, arguably the largest in our body. 

Meet Sarcopenia: The New Disease on the Block 

Sadly, we now have identified a new enemy: Sarcopenia.

Sarcopenia is the age-related loss of muscle size, strength and function. It is not pretty on the outside or on the inside at the cellular level.

The average decline from peak muscle strength by age 40 years is 16% and reaches 40.9% for people aged 60+ years. Muscle mass decreases by approximately 3-8% per decade after 30 years of age and accelerates after age 60. By 80 years, if the trend is not reversed, we can expect to be hobbling along with 50% of our youthful muscle.

Sarcopenia leads to not only to reduced muscle performance and function but increased frailty, disability, loss of independence, morbidity and mortality.

Aging is associated with a decline in important hormones, including Insulin-like growth factor-1, human growth hormone and testosterone all of which supports muscle health and growth.

As we age, we lose motor neurons in the spinal cord that travel to our muscle fibers. As these nerve connections are lost, our muscles weaken. 

The combination of disuse, reduced hormones, injury, inflammation, disruption of neuronal connection and poor absorption of dietary protein leads to the loss of our precious muscle and the replacement with fat.

From Metabolism to Immunity: 7 Ways Skeletal Muscle Powers Our Health

1.   Impacts Metabolic Health: Healthy skeletal muscle is essential for clearing glucose from the blood stream after eating to keep our blood glucose at normal levels. It accounts for 80% of the glucose uptake. Insulin resistance which leads to Type 2 Diabetes and a whole cascade of chronic diseases begins in aging skeletal muscle.

Building more muscle will improve how your body uses glucose so less insulin, our fat storage hormone, is needed. More muscle means more mitochondria to take up and utilizes glucose boosting our metabolic health.

2.   Enhances Cognition: Research suggest that sarcopenia and cognitive decline share the same root cause. Loss of muscle strength (not muscle mass) and gait speed are well documented as being associated with cognitive decline. There are studies indicating that improving muscle strength improves cognitive function in some areas.

The potential mechanisms linking poor brain and skeletal muscle health include low circulating Vitamin D, inflammation, oxidative stress and certain lifestyle risk factors.

Inflammation and oxidative stress are well recognized players in accelerated aging and chronic disease. Increased body fat is an inflammatory state. Biomarkers of inflammation namely Interluekin 6 (IL-6), and Tissue Necrosis Factor alpha have been associated with muscle atrophy and age-related cognitive decline in humans.

It is well known that exercise reduces inflammation in the body and is an effective strategy for insulin resistance. When healthy skeletal muscle contracts it releases anti-inflammatory compounds one of which is Brain-Derived Neurotrophic Factor (BDNF) which protects the health of neurons in the brain. It plays an important role in learning and memory. Low levels of BDNF are associated with neuro-degenerative diseases like Alzheimer’s Disease, Parkinson’s disease and multiple sclerosis.

Lifestyle risk factors including physical inactivity, poor diet and smoking are also part of the association between loss of muscle and cognitive decline.

3.   Calms Mood: One large study in adults found that a lower hand grip strength was associated with a higher incidence of anxiety and depression. Chronic low-grade inflammation and low BDNF has been consistently shown to be associated with mood disorders.

By lowering inflammation and raising BDNF, strength training to maintain healthy skeletal muscle then is a great way to enhance mood.

4.   Fortifies Immunity: Glutamine, an amino acid produced by active skeletal muscle is the main source of energy for our immune cells. Skeletal muscle being an essential source of IL-6 has been shown to have anti-inflammatory and anti-oxidants properties helping to modulate the immune system.

5.   Reduces Fall Risk: Strong muscles, particularly our quadriceps, are critical for balance and coordination dramatically reducing the risks of falls.

6.   Improves Survivability and Longevity: Skeletal muscle is the organ of longevity. It serves as a reservoir for amino acids when needed and not immediately available from the diet.  These amino acids are used make new proteins, enzymes, neurotransmitters and to optimize our digestion, immune function and brain health. The more skeletal muscle we have the more survivability for the storms of life like COVID or cancer treatments.

7.   Enhanced Quality of Life and Independence: Better muscular health means more mobility, energy, and less chronic illness allowing us to engage more fully with the world around us. It also allows us to enjoy and cherish our independence and vitality.

3 Essential Steps to Combat Sarcopenia: 

•  Dietary Protein: In order to maintain optimal skeletal muscle, we need to eat MORE protein, not less as we age. We need to double the current, outdated RDA recommendations of .8 gm/kg.

  To prevent and reverse sarcopenia, experts in the field are advising 1 gram protein/lb of ideal body weight (1.6- 1.8 gm/kg).

  To improve the efficiency of skeletal muscle growth it is best to bolus it with 30-50 grams per meal per day. This prompts the nutrient sensing pathways to lay down new muscle protein.

  This minimum of 30 grams of high-quality animal protein or whey protein will contain adequate levels of leucine, the very important essential amino acid needed to trigger protein synthesis. This leucine threshold is 2.5 gms.

  For vegans, this is more difficult due to lower leucine content in plants, lower absorption from plant foods and the need to eat higher volumes to achieve sufficient protein from these sources. To help this process, tofu or beans (black, pinto or lentil) can be consumed along with a scoop of powered branched chain amino acids which contains leucine.

       Rough Guide to What 30 grams of Protein Looks Like:

                Red Meat: 4 Ounces

                Chicken: 4 Ounces

                Fish: 6 ounces

                Whey Protein: 1-2 scoops

                Eggs: 5

                Cottage Cheese 2%: 1 cup

                Tofu cooked: 1 and ½ cups

                Black/Pinto/Lentils: 2 cups

                Quinoa cooked: 4 cups

•  Resistance Training: Research suggests that resistance exercise has a bigger impact on metabolism and body composition than nutrition.

  It is well established that weight or resistance training plays a profound role in increasing muscle strength, size and function in older people. The goal is not how heavy the weight but the level of exertion or going to “fatigue”.

  A well-designed, progressive resistance exercise training program with adaptations to any physical limitations will have positive effects on both the nervous and muscular systems while enhancing muscle mass, strength, balance and coordination. It also reduces inflammation and improves metabolic health.

•  Omega 3 Fatty Acids: There is mounting evidence for the beneficial effects of omega 3 fatty acid supplementation for the prevention and treatment of sarcopenia. Previous randomized control trials have shown that omega 3 supplementation stimulates muscle protein synthesis in older adults.

  The significant anti-inflammatory effects of omega 3 fatty acids along with the effects of improving insulin sensitivity have also been positively associated with improved muscle mass, strength and physical performance.

Learning these steps, let us embrace a lifestyle that strengthens our muscles for a longer, healthier, active life.