Beyond its role in movement and posture, muscle is now 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 metabolic 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 blood sugar regulation and 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 for blood sugar regulation and growth hormones for protein synthesis). Muscle also responds to 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.”
Decreased muscle mass, alongside reduced strength, flexibility and stamina are common characteristics of old age. These physical changes increase frailty and underscore risk factors for falls, fractures and overall mortality. Conversely, 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 that higher skeletal muscle mass is associated with greater strength, independence, and vitality into later years of life helping people live longer and age better.
Muscle health is intrinsically tied to mitochondrial health. More and more, science is demonstrating the mitochondrial health lie at the centre of age related chronic diseases and metabolic dysfunction.
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 the reduction of skeletal muscle mass.
To slow 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
Exercise – Both endurance and resistance training are essential. Endurance training improves cardiovascular health, oxygen uptake, and cellular respiration (mitochondrial health) while resistance training builds and maintains muscle mass, thereby improving strength.
Beyond traditional exercise training, simple daily movement is an important part of ensuring long term musculoskeletal health.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. These levels, combine with resistance training, support muscle protein synthesis and avoid muscle protein breakdown.
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 signaling, 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.
Muscle is a metabolic regulator, a protector of health, and a cornerstone of longevity. Building and maintaining muscle is one of the most powerful tools for supporting long-term metabolic and overall health.