Unless you are suffering a prolonged midlife crisis, life really does get better after 40—we can start to enjoy the fruits of our labour, care less about what people think, and (hopefully) have life worked out. Physically, things are still okay. But the average person would have lost 3-8% muscle mass since turning 30, and this trend will continue each decade.
Nearly half of our body weight consists of muscles—over 600 different types. Muscles are made of fibres, and more fibres mean greater muscle strength. They all stretch and contract, but distinct muscle groups have very different functions.
Smooth muscles keep organs working behind the scenes (e.g. digesting food, expelling the solid and fluid by-products, maintaining blood flow, delivering babies, and even helping eyes see), and cardiac muscle works 24/7 to keep the heart beating.
Skeletal muscle contains the most tissue and is the body’s largest protein store. Skeletal muscle gives bodies their shape, maintains posture, moves the body on command and generates heat. It even mediates insulin production, supporting evidence that improved muscle tone can help control blood sugar levels.
Severe muscle loss affects 5-13% of people by 60-70 years, increasing to 11-50% of people over 80. As skeletal muscle mass declines with age, so does muscle strength, power and balance. Professor Irwin Rosenberg, of the Jean Mayer USDA Human Nutrition Research Center on Aging, proclaimed, “no decline with age is more dramatic or potentially more functionally significant than the decline in muscle mass.”
Lost muscle mass can increase risk of sudden falls, fractures and mortality. Sarcopenia—age-related loss of lean tissue mass and function—is a serious, multifactorial condition that can creep up unexpectedly. It affects an estimated 29% and 33% of older people living in the community and in long-term care, respectively—and this is likely to increase with our aging population.
Forced hospital rest can worsen sarcopenia. Some older adults may never recover from extra muscle mass lost from injury and hospitalisation, leading to accelerated breakdown of body tissues, poor clinical outcomes and increased hospital costs. When severe, sarcopenia results in 79% increased risk of disability.
Lifestyle behaviours make up much of the difference between healthy and unhealthy aging: most notably diet quality and exercise. Age-related and severe loss of muscle mass can be reduced with physical activity (especially resistance training) and nutrition.
Protein and amino acids (protein building blocks) from absorbable sources like whey are key nutritional targets for improving muscle mass, strength and physical performance. Adults with protein-energy malnutrition and unintended weight loss also need extra calories from food to prevent their body breaking down muscle protein for energy.
Vitamin D may improve muscle strength, especially in patients over 65 with low Vitamin D (<30 nmol/L). Creatine supplementation, combined with resistance training, might increase upper body strength and reduce muscle aging, and one study reports possible benefits of leucine (an amino acid that stimulates muscle protein synthesis). A recent review further identified a potential role for minerals (particularly magnesium, selenium and zinc) in preventing and treating sarcopenia.
Increased muscle strength can not only enhance treatment outcomes, morbidity and blood sugar control, it may also improve sleep and mental health—hence better quality of life with aging.