Skeletal muscle, which constitutes 30% to 40% of your total body mass, is a fundamental tissue responsible for a wide range of bodily functions. These muscles are attached to bones by tendons and are under voluntary control, allowing for conscious movement. Beyond enabling physical actions like walking, chewing, and breathing, skeletal muscles also play a role in maintaining posture, stabilizing joints, regulating body temperature, and storing nutrients. Maintaining adequate skeletal muscle mass is a significant aspect of overall health.
Understanding Low Skeletal Muscle
Low skeletal muscle mass refers to having less muscle than is typical for an individual’s age and gender. This reduction can affect daily physical function, leading to diminished strength and endurance.
A common condition associated with low skeletal muscle is sarcopenia, defined as the progressive loss of muscle mass and function, often linked with aging. This condition can lead to a decline in physical ability, an increased risk of falls, and fractures. Another related term is muscle atrophy, which describes the loss or thinning of muscle tissue, resulting in a decrease in muscle mass and strength. While often associated with aging, sarcopenia and muscle atrophy can significantly impact mobility, balance, and overall quality of life, extending beyond mere physical strength.
Factors Contributing to Muscle Loss
Several factors contribute to the reduction of skeletal muscle mass over time. Aging is a primary driver, with muscle mass typically peaking around age 30 and then decreasing by 3% to 8% per decade afterward. This age-related muscle loss, known as sarcopenia, can accelerate after age 60, making daily activities more challenging. The body’s production of proteins necessary for muscle growth also diminishes with age, causing muscle cells to shrink.
Physical inactivity and a sedentary lifestyle also play a substantial role in muscle loss. Prolonged periods of immobility, such as bed rest or a desk-bound job, can cause muscles to break down as the body conserves energy. Even just five days of single-leg disuse can lead to a marked decrease in muscle cross-section area and strength.
Inadequate nutrition, particularly insufficient protein intake, impairs muscle growth and maintenance. Diets lacking in lean protein, fruits, and vegetables can lead to muscle atrophy. Chronic diseases also contribute to muscle wasting. Conditions like diabetes, heart failure, kidney disease, cancer, and HIV can all accelerate muscle loss. Finally, chronic low-grade inflammation, which increases with age, can negatively affect skeletal muscle metabolism and contribute to reduced muscle mass and strength.
Rebuilding and Maintaining Muscle Mass
Reversing and preventing low skeletal muscle involves a multi-faceted approach, with resistance training being an effective strategy. This type of exercise, which includes activities like weightlifting, resistance bands, or bodyweight exercises (e.g., push-ups, squats), increases muscle strength by working muscles against a force. For optimal muscle growth, it is generally recommended to perform 3-4 sets of 8-12 repetitions per exercise, aiming to fatigue the muscles. Beginners can start with two or three sessions per week, allowing at least 48 hours of rest for each muscle group to recover and grow.
Adequate protein intake is another foundational element for muscle repair and growth. While a recommended dietary allowance exists, active individuals or those aiming to build muscle may benefit from higher intakes, ranging from 1.2 to 2.0 grams per kilogram of body weight daily. Spreading protein intake throughout the day can help maximize muscle-building benefits. Good dietary sources include lean protein from animal-based foods like fish, chicken, and eggs, as well as plant-based options like beans, lentils, nuts, seeds, and quinoa.
Beyond protein, a balanced diet providing adequate calories, vitamins, and minerals supports overall muscle health. Vitamin D, for instance, is important for skeletal muscle and bone health. While sunlight is a primary source, dietary supplements or fortified foods can help ensure sufficient levels, especially during months with less sun exposure. Maintaining an active lifestyle, even through light physical activity like walking or gardening, contributes to muscle maintenance. Consulting healthcare professionals or dietitians can provide personalized advice, especially for individuals with underlying health conditions.