Managing Muscle Loss For Life—Causes, Types & Treatment
Managing Muscle Loss For Life—Causes, Types & Treatment
The human body, with all of its intricacies and complexities would cease to function without the support of fibrous tissue, known as muscle. Each day, the cardiac muscle, responsible for the contraction of the heart pumps 2000 gallons of blood throughout the body. Smooth muscles create the blood vessel walls of our circulatory system, and skeletal muscles allow our bodies to move.
With more than 650 separate muscles to maintain, the risk for muscle loss, and diminished strength is high over a lifetime.
When we are young, approximately 50% of our body weight is made up of lean muscle mass. By the time we reach age 75 however, muscle has been reduced to only 25% of our total body weight.
Where does it all go? Why We Lose Muscle
Muscles atrophy, meaning muscle tissue wastes away.
Types of muscle atrophy include:
- Physiologic Atrophy
- Pathologic Atrophy
- Neurogenic Atrophy
Causes of Muscle Loss
Physiologic atrophy occurs because of lack of activity. Muscle tissue becomes unhealthy without exercise.
Who is most affected by physiologic atrophy?
- Individuals who sit while at work
- Individuals with limited mobility
- Individuals who are bedridden
- Those who have suffered a stroke or other brain disease that affects their ability to move their limbs
- The few who experience space flight (low/no gravity)
This type of muscle loss has several causes including:
- Cushing Disease
- Overuse of corticosteroids
Neurogenic atrophy is considered the most severe form of muscle atrophy.
Neurogenic atrophy may be caused by a number of medical conditions including injury to a nerve that is connected to the muscle. A disease involving nerves connected to muscle may also be to blame.
Features of Neurogenic atrophy
This type of muscle atrophy usually occurs more suddenly than physiologic atrophy.
The following diseases or conditions may negatively affect nerves used to control muscles.
- Amyotrophic lateral sclerosis, also known as Lou Gehrig disease, or ALS
- Single nerve damage, as in the case of carpal tunnel
- Guillain-Barre syndrome
- Nerve Damage due to serious injury, diabetes, alcoholism
- Injury to the spinal cord
- Corticosteroid use long-term
- Rheumatoid arthritis
- Severe lack of nutrition
- Muscular Dystrophy
Sarcopenia, Muscle Loss in Aging
Beyond the age of 30, individuals lose between 3-8% of muscle mass for every decade thereafter.
How common is sarcopenia?
In the U.S., about 20% of (community dwelling) adults under age 70 have sarcopenia. And 50% of adults over age 80 are considered sarcopenic.
Sarcopenia involves the loss of both muscle mass, and muscle function and strength. The term, “sarcopenia” has been used to describe loss of muscle. The actual term is rooted in the Greek words referring to “loss of flesh”. As we age, the number and size of muscle fibers decreases as infiltration of adipose tissue into skeletal muscle increases.
Age-related sarcopenia often involves decline in one or more areas including:
- Neurological decline
- Hormonal changes
- Inflammatory pathway activation
- Declining activity
- Chronic illness
- Fatty infiltration
- Poor nutrition
Diabetes, Obesity, and Muscle Loss
Studies suggest that impaired gait, and slow walking speed in connection with diabetes will further decrease muscle tissue in adults, age 65 and older. Wasting of muscles in the shoulders and hip area, known as limb girdle wasting also contribute to a diagnosis of diabetic amyotrophy.
Obesity can accelerate muscle loss due to inactivity as well. A diet high in fat, and low in protein, a reduction in energy expenditure, and possible hormone changes as a result of excess fat/weight can all contribute to muscle loss.
Other reasons for muscle loss may include:
Hypogonadism in Men—Loss of Testosterone
Many hormone levels change with age. In men, the loss of total testosterone occurs at about 1% every year after age 30. By the time a man reaches 70-80 years old, dhea (precursor to testosterone) levels are about 20% of what they were at age 20. This loss of male androgen hormone ultimately leads to decreased muscle and lean tissue, and greater fat mass in males. Mobility may be more limited in older men as well.
Vitamin D Deficiency
A deficiency in vitamin D can cause muscle weakness, muscle fiber atrophy, and an increase in intramuscular fat. Vitamin D deficiency is more common in older adults than in younger individuals.
Other diseases and conditions associated with muscle loss include:
- Rheumatoid arthritis
- Peripheral arterial disease
- Congestive heart failure
- Kidney disease
- Cirrhosis of the liver
Bed rest though necessary to recover from a number of illnesses and injuries can be detrimental to muscle health. Muscle loss due to inactivity primarily affects the lower body and is accelerated in the early days and weeks of inactivity, as in the case of complete bed rest at home or a prolonged hospitalization. This contributes to negative outcomes including an increase of readmission, and a reduction in the ability to perform everyday tasks for living.
Living and working with even minor muscle loss can negatively impact production and mobility, as well as increase the risk for fractures and falls. Quality of life, relationships, and overall health all suffer when muscle tissue degrades and disappears.
How is muscle loss diagnosed?
Muscle loss causes a loss of both power and strength. Often, individuals notice weakness or a size difference between one leg, arm, or hand, over another.
A clinical diagnosis for a specific type of muscle loss must be made by a medical practitioner, however. The term, “dynapenia” refers specifically to loss of muscle strength and may be included in the diagnosis.
To help determine if there is muscle loss, a physician will usually conduct a complete physical examination, gather a thorough medical history, and take measurements of muscles affected throughout the body for comparison.
Tests to help determine if muscle loss exists may include:
- Blood tests
- CT scan
- Electromyography (EMG)
- MRI scan
- Muscle biopsy
- Nerve biopsy
- Nerve conduction study
Prevention and Treatment of Muscle Loss, The Good News
While muscle loss may be an inevitable part of aging, disease or a physical condition, fortunately it can be rebuilt, and strength can be restored.
Turns out, protein synthesis and muscle growth are highly responsive to diet and exercise.
When protein is consumed in the diet or through natural supplementation, the body breaks it down and converts it to important amino acids. These acids are the foundation for healthy muscle growth and maintenance.
As we age, men especially experience what is known as “anabolic resistance”. This inhibits the body’s natural ability to not only breakdown, but to create necessary protein. To counteract this, nutritionists recommend 1-1.3 grams of protein per kilogram of body weight for aging individuals daily.
In older individuals diagnosed with sarcopenia, a diet supplemented with just 16 grams of essential amino acids daily, increased lean muscle mass after only 6 months, with further muscle mass at 18 months. Insulin sensitivity improved as well.
Best foods for high protein providing essential amino acids include meat, eggs, and milk. While red meat may be high in saturated fat, there are still healthy options available.
- 3.5 ounces of lean chicken or salmon (31 g and 24 g)
- 6 ounces of plain Greek yogurt (17 g)
- 1 cup of skim milk (9 g)
- 1 cup of cooked beans (about 18 g)
Protein powders can also be used to supplement a healthy diet, offering about 30 grams of protein per scoop.
Progressive Resistance Training (PRT) for Muscle Loss
PRT involves progressive exercises to gradually build muscle over time. Quick movements against resistance, like rapidly rising from a seated position or pushing off a step when taking the stairs are a healthy start to resistance training. As individuals become more fit they can progress toward a more structured and specific PRT program. In published studies involving men age 50-83, those who participated in progressive resistance training registered a 2.4 lb. increase in lean body mass alone.
PRT and Obesity Related Muscle Loss
In research trials, progressive resistance training, together with aerobic exercise resulted in gain in muscle mass, increased strength in muscles, and overall improvement with insulin resistance in obese individuals between 60 and 80 years old.
When developing an exercise regimen for PRT, it is important to consider load and repetitions, with built in adequate rest periods.
A sample workout might include:
- 8 to 10 exercises focusing on all major muscle groups
- Sets of 12 to 15 reps, medium difficulty
- 2-3 workouts/week
Workouts should get progressively more difficult either by adding a second set of exercises, etc., or reducing the number of reps and increasing weight.
Benefits of Strength Training
- Gentle yet powerful exercise regimen
- Can be done in a short amount of time
- Requires very little equipment
- Can usually be safely performed by individuals with health problems
- Boosts strength, energy, and vitality
Other Treatment for Muscle Atrophy
- Exercise in a pool
- Physical therapy
- Ultrasound therapy
- Physical therapy
While the loss of muscle will likely impact each of us at some point in our lives, the time to take steps to minimize its negative effects is now.
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4Kalyani, Rita Rastogi, et al. Advances in Pediatrics., U.S. National Library of Medicine, Oct. 2014, www.ncbi.nlm.nih.gov/pmc/articles/PMC4156923/.
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