Muscle loss is inevitable with age. After age 30, most people lose about 3 to 5 percent of their muscle mass each decade, with the most significant losses occurring in inactive people. At around age 60, muscle loss accelerates. Research indicates that after age 80, 11 to 50 percent of people have sarcopenia, the significant loss of skeletal muscle mass, muscle strength, and function that occurs during advancing age.
Lean body mass is primarily made up of skeletal muscle. Reduced skeletal muscle mass and function in adults are associated with chronic diseases, poor quality of life, physical disability, increased risk of fractures, and risk for frailty. Muscle loss becomes a vicious cycle since it promotes injury, contributing to a more sedentary phase of life, leading to muscle loss.
Causes of muscle atrophy
The leading cause of muscle atrophy (sarcopenia) is aging itself. Several things happening in the body during this time can lead to muscle loss. These include:
• Reduced activity in nerve cells responsible for coordinating movement
• Lower levels of growth hormones, testosterone, and insulin-like growth factors
• A reduced ability to convert protein into energy
• Elevated inflammation
• Anabolic resistance, the age-related suppression of muscle protein synthesis after a dose of protein/amino acids
In addition to aging, muscle atrophy can also be caused by disuse, such as when patients are sedentary for long periods.
Diagnosing muscle atrophy
Muscle atrophy is usually diagnosed by measuring loss of muscle mass, strength, and other factors related to muscle loss. A hand grip test to measure grip strength is also an effective tool. In addition, symptoms are evaluated:
• Muscle weakness
• Loss of stamina during activity
• Difficulty performing daily activities
• Walking slowly
• Difficulty climbing stairs
• Balance issues
• Increased incidence of falls and
• Shrinking muscles.
Muscle loss is a risk of weight loss
Maintaining muscle while losing fat is critical to successful weight loss efforts. This is one of the challenges of the popular GLP-1 agonist drugs, which lead to rapid weight loss and results in both fat loss and muscle loss during long-term treatment. Muscle is involved in weight loss in many health-sustaining processes:
• Regulating metabolism: As metabolically active tissue, muscle burns more calories at rest than fat tissue. The preservation of muscles leads to a higher basal metabolic rate, essential for keeping the extra weight off in the long term.
• Preserving physical function and strength: Maintaining muscle mass helps patients stay active as they age.
• Maintaining insulin sensitivity and blood sugar: Muscles are involved in glucose metabolism and insulin sensitivity. On the other hand, muscle loss can lead to disrupted glycemic control, even in patients who are losing fat.
• Maintaining weight over time: Keeping the pounds off over time is more difficult if muscle is lost while on a weight-loss diet. The lower metabolic rate accompanying reduced muscle mass makes patients more prone to regain the lost weight.
Therefore, sustaining muscle during weight loss is critical to maintaining a healthy weight over time.
The solution: Inhibiting myostatin
Much research around therapeutic interventions to prevent, slow, or reverse sarcopenia spotlights elevated levels of myostatin, which suppresses muscle growth and is found primarily in skeletal muscle, which reduces protein synthesis.
Evidence suggests that myostatin levels rise during aging. In a study of younger, middle-aged, and older men and women, serum myostatin levels increased with age. The study also indicated that myostatin levels are the highest in physically frail older women and that the higher the skeletal muscle mass, the lower the myostatin levels.
In rodent models, animals with a mutated or deleted myostatin gene experience beneficial effects such as resistance to obesity, hepatic steatosis, atherogenesis, and macrophage infiltration/activation in skeletal muscle and adipose tissue. Myostatin-null mice also experienced increased bone mineral density.
According to researchers writing in the journal Gerontology, “Myostatin inhibition provides a promising means to attenuate or reverse skeletal muscle loss in the context of sarcopenia as well as cachexia (disease-associated muscle loss), and to enhance skeletal muscle regeneration in the context of congenital disease (i.e., muscular dystrophies) and injury.”
The first way to decrease myostatin also builds muscle: resistance exercise. Try body-weight exercises, such as push ups, squats, planks and lunges; weight machines at the gym; or hand weights and resistance bands. Aim to work any muscle group (legs, arms, back) every other day and gradually increase the challenge.
Supplementation may also help. Studies suggest a supplement derived from fertilized egg yolk (Fortetropin) increases lean body mass, reduces markers of protein breakdown, and is associated with muscle growth.
Additional factors
Additionally, I test for diabetes, altered cortisol levels, and suboptimal levels of key hormones like DHEA, growth hormone, and testosterone in both men and women, as these can impact muscle health. Finally, I prioritize good sleep hygiene, including both quality and quantity, and assess sleep apnea, as restful sleep is crucial for the body’s recovery and healing processes.
