Growing old gracefully is not for the faint hearted, the brittle boned or the weak. Brittle bones due to osteoporosis, in combination with muscle loss (sarcopenia), can result in falls and broken bones. Muscle mass and strength, in particular, are very important to the elderly, as they need muscle strength for mobility and balance.
Aging-related muscle atrophy (loss of muscle tissue) is the most common type of muscle atrophy and is linked to significant impairment of muscle function, such as muscle weakness and slowing of movement. This probably represents the most dramatic and significant of all the changes that are experienced during the aging process, and is referred to as sarcopenia.
What is sarcopenia?
Sarcopenia refers to the aging related involuntary loss of skeletal muscle mass and strength, as well as muscle function. The decline in muscle strength gradually takes place in a linear fashion, starting in the 4th decade of life, with a dramatic decline during the 8th decade of life, with up to 50% of muscle mass and strength lost by then. Muscle degeneration is a common condition in elderly people and is associated with disability, functional decline, frailty and fall related injuries. It is estimated that about half of those over the age of 80 are impaired with sarcopenia, literally meaning “lack of flesh”.
Effects on the body
Cell growth processes in the body are called anabolism, while the teardown processes are called catabolism. There is normally a balance in the body between growth and teardown signals, allowing muscle to keep its strength over time. However, during normal aging processes, the body becomes resistant to the anabolism related growth signals and an imbalance towards the catabolism related teardown processes starts to develop, resulting in the degenerative condition of sarcopenia.
A number of other factors also play a role in age related muscle loss, such as:
• Disuse of muscles, either through a sedentary lifestyle, or immobility due to illness, can lead to faster muscle loss and is one of the strongest triggers of sarcopenia.
• Decreases in walking and other regular activities lead to decreases in muscle mass and strength, which can become a vicious circle as you are more prone to experience fatigue, which in turn makes it difficult to return to normal levels of activities.
• A diet that is unbalanced and lacking in the building blocks needed for muscle growth, such as an insufficient intake of calories and protein, can result in diminished muscle mass. Scientist recommend that older people consume 25-30 grams of protein at each meal, in order to prevent sarcopenia.
• Inflammation caused by chronic diseases and health conditions can result in muscle loss, as long-term inflammation tends to disrupt the normal balance of muscle teardown and growth.
• Health conditions that place great stress on the body can lead to muscle loss and accelerate sarcopenia, for example, conditions such as chronic liver or kidney disease, chronic heart failure, cancer and cancer treatments can all increase stress on the body.
• Muscle function decline during aging is largely due to the progressive loss of motor neurons, affecting neuromuscular junctions and muscle fibers. (A neuromuscular junction is a chemical synapse formed by the contact between a motor neuron and a muscle fiber, where signals are transmitted to the muscle fiber, causing muscle contraction.)
• Hormones play an important role in muscle mass maintenance. Growth hormone is one of the hormones that usually decrease with aging, along with other hormones, such as testosterone and estrogen.
• Obesity and fat in skeletal muscle also play a role in the development of sarcopenia, as research has shown that increased fat mass is associated with lower muscle quality.
• Skeletal muscle stem cells, which are crucial to the regeneration of skeletal muscle, appear to be compromised in older people.
• Losing muscle mass decreases insulin sensitivity, as the muscle tissue acts as a reservoir for the disposal of glucose.
Interventions to prevent or slow down sarcopenia
While some of the causes of sarcopenia are inevitable consequences of aging, some are preventable by following a healthy diet and doing regular exercises. As muscle loss takes place much quicker than it is built, it is important to continuously promote and maintain muscle mass and strength as you get older. The best way to fight sarcopenia is to keep the muscles active through a comprehensive training program that combines resistance (weight) training and aerobic exercise.
• Resistance training includes moving the body against gravity (walking, jogging, push-ups), weightlifting, and pulling against resistance bands. Resistance training has an beneficial effect on the neuromuscular system, on protein synthesis, and relevant hormones. Tension on muscle fibers results in growth signals, which leads to increased strength, while also increasing the action of growth-promoting hormones. These signals cause muscle cells to grow and repair themselves by making new proteins and turning on muscle stem cells. Regular resistance training is the most direct way to prevent muscle loss and increase muscle mass and strength.
• Aerobic exercise and endurance training are forms of sustained exercise that increases the heart rate and can help to control sarcopenia. Daily walking, in particular, is an easy way to prevent and reverse sarcopenia, as it is an activity that you can do anywhere and at a time that suits you. Best of all, it is free. Aerobic exercise has been shown to increase muscle protein synthesis, which is an important function in maintaining muscle mass and strength.
• Effective exercise against sarcopenia includes at least 150 minutes of aerobic exercise and two strength training sessions per week. Both types of exercise are needed to combat sarcopenia.
There is important synergy between exercise and nutrition for muscle maintenance. Amino acids, which are the building blocks of protein, are important components for muscle building and maintenance, as they also act as signaling molecules that trigger muscle growth. Higher doses of some key nutrients can help to prevent or curb sarcopenia and improve muscle growth (in response to exercise), such as:
• Protein in the diet signals the muscle tissues to build and strengthen, but with aging the muscles become resistant to this signal, which means larger quantities of protein is needed in the diet to increase muscle growth.
• The amino acid leucine in particular helps to regulate muscle growth and is found in foods such as whey protein, eggs, fish and meat.
• Vitamin D deficiency has been linked to sarcopenia.
• Omega-3 fatty acids, either from fatty fish or supplements, can signal muscle growth directly, in addition to the anti-inflammatory benefits of omega-3.
• Creatine is a protein that is normally made in the liver in sufficient quantities to prevent a deficiency, but in the elderly, additional creatine in the diet from meat or supplements, can benefit muscle growth.
Conclusion:
Apart from aging, sarcopenia is driven by low levels of physical activity, poor nutrition with low protein intake, in particular; chronic inflammation, and stress. It can be beaten with interventions that target these complex biological processes through a less sedentary lifestyle, optimal nutrition, as well as interventions to reduce the individual’s chronic inflammation and stress factors. The sooner these interventions start, the easier to grow old gracefully with mobility and agility!
Sources:
The importance of muscle in healthy aging. Published 14 March 2020. Dr Mercola. (www.mercola.com)
How to fight sarcopenia (muscle loss due to aging). Published 25 May 2017. Healthline. (www.healthline.com)
Sarcopenia: Aging-related loss of muscle mass and function. Published 14 November 2018. Physiological Reviews, journal of the American Physiological Society. (www.journals.physiology.org)
Sarcopenia in older adults. Published November 2012. HHS Public Access – Author Manuscript, PMC. National Center for Biotechnology Information. US National Library of Medicine. National Institutes of Health. (USA). (www.ncbi.nlm.nih.gov)
Preventing sarcopenia. Published online. International Osteoporosis Foundation. (www.iofbonehealth.org)
Aging changes in hormone production. Published online. MedlinePlus. US National Library of Medicine. (www.medlineplus.gov)
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