Role of Muscle in Metabolic Health and Longevity

Beyond its role in movement and posture, muscle is well established as an endocrine organ playing a central role in metabolic health and longevity. Skeletal muscle is the largest organ system in the body by weight and plays a vital role in glucose homeostasis and metabolism regulation.

Muscle as a Metabolic Powerhouse

Muscle is a metabolically active organ system that plays a central role in regulating blood sugar and is responsible for up to 80% of glucose uptake after meals.

Dietary carbohydrates are digested into glucose and absorbed into the bloodstream. To maintain stable blood sugar levels, the body releases insulin, which acts like a key that allows glucose to enter cells. Glucose is stored as glycogen in the liver and muscles for short-term energy needs. Any excess glucose is converted into fat, primarily triglycerides, and stored in adipose tissue. Therefore, having greater muscle mass increases the body’s capacity for glucose storage and minimizes the amount of glucose that is converted into fat for storage in adipose tissue. This is the mechanism by which muscle supports metabolic health.

Muscle as an Endocrine Organ

Skeletal muscle is well established as an endocrine organ that both secrets and responds to hormone messaging. Muscle receives messages from metabolic hormones (insulin and growth hormones) as well as thyroid and sex hormones. Muscle cells release a class of hormone called myokines in response to muscular contractions during movement and exercise. Myokines have far reaching positive effects throughout the body. Myokines positively influence metabolism, blood sugar balance, immune function, bone and brain health. Myokines improve insulin sensitivity, promote mitochondrial health, reduce inflammation and have neuroprotective effects in the brain.

Muscle’s role in Longevity

Muscle is sometimes referred to as the “organ of longevity.”

Beyond the cellular and biochemical changes that occur with age, visually decreased muscle mass with reduced strength, flexibility and stamina as common characteristics of old age. These physical changes increase frailty and underscore risk factors for falls, fractures and overall mortality. Increased skeletal muscle strength and power help prevent falls and fractures by improving one’s ability to react quickly and catch oneself after loss of balance. 

Studies show higher skeletal muscle mass is associated with greater strength, independence, and vitality into later years of life helping people live longer and age better.

Why We Lose Muscle with Age

Skeletal muscle mass and strength peaks in our 30s from which time it decreases, slowly at first, progressively accelerating with age. Sedentary lifestyle, hormonal changes, impaired digestion and poor diet all compound the biological processes the contribute to reduction of skeletal muscle mass affecting strength, stamina, balance and flexibility.

To slow down this trajectory, exercise is paramount, adequate protein intake is essential and new research points to the importance of cellular hydration to maintain muscle strength and function.

Building and Protecting Muscle

1. Exercise is paramount – Both endurance and resistance training are non-negotiable.Endurance training improves cardiovascular health, oxygen uptake, and cellular respiration (mitochondrial health) while resistance training improves strength and muscle mass. Intensity depends on current health status. For some endurance training means a 45-minute run or bike ride, for others starting with a 10-minute walk is enough and build from there. The same principle applies to resistance/strength training.
   Beyond what we think of exercise training, simple daily movement is essential and an important part of ensuring long term musculoskeletal health. So stay active all day by taking ‘sitting breaks’ throughout the day. Get up from your desk to walk around the block, climb stairs, carry groceries, dance in your kitchen. Every bit of movement reinforces muscle function and keeps metabolism humming.

2. Prioritise Protein - Protein provides the building blocks for muscle growth and repair. Current guidelines recommend 0.8g per kg of target body weight per day. However, to build and protect muscle in midlife and beyond, target 1-1.2g of protein per kilogram of body weight per day spread across three meals. Such levels support muscle protein synthesis and avoid muscle protein breakdown.

3. Cellular hydration – Cellular hydration has been demonstrated as an important component for maintaining musculoskeletal health and function. Hydration extends beyond fluid intake. Mineral balance is essential for optimising cellular hydration. Electrolytes, namely sodium, potassium and magnesium, regulate movement of water across cell membranes supporting nerve signalling, muscle contraction and cellular communication, essential for muscle function.
   A balanced diet that includes half a plate of vegetables at every meal will supply essential minerals of electrolyte balance. Fluid intake depends on exercise, respiration, and fluid content from meals, but a general guideline is to aim for about 25-40ml per kg of body weight from water, herbal teas and soups.

The Bottom Line

Muscle is a metabolic regulator, a protector of health, and a cornerstone of longevity. Building and maintaining muscle is one of the most powerful investments you can make for your long-term metabolic and overall health. If you want to age well, protect your metabolism, and live vibrantly into your later decades, it is essential to prioritise muscle.