The Older You Get the More Protein to Stave off Muscle Loss: Part 1 – What Is Skeletal Muscle?
What Are Skeletal Muscles?
Skeletal muscles are made up of two types of tissue; connective tissues (muscle fibers) and bone. Bone is found in your bones (osteoporosis). There are three main kinds of skeletal muscle fibers: type I, IIa, and IIx. Type I skeletal muscle fibers are slow twitch or slow contractile fibers. They have short, fast acting contraction times. These are the most common type of skeletal muscle fiber. Type IIa skeletal muscle fibers are characterized by their ability to produce large amounts of force at low speeds and high intensities. Type IIb skeletal muscle fibers increase both these characteristics but they also require higher levels of oxygen than other types of skeletal muscles due to their greater size and number of mitochondria (the “powerhouses” of cells). Type IIx skeletal muscle fibers are characterized by their ability to produce small amounts of force at low speeds and high intensities. They also have very long contraction times. However, unlike other types of skeletal muscle fibers, they do not require a large amount of oxygen because they contain many mitochondria.
Skeletal muscles are attached to bones by tendons. The skeletal muscles contractions cause the bone to move and by themselves can’t produce movement or action. They can only cause a movement at a joint which is then used for other purposeful actions such as using a knife and fork to eat food. Some examples of skeletal muscle are the muscles in your forearm, head, neck, eyelids, fingers, toes, feet, and chest.
Skeletal muscles work in coordination with the central nervous system (CNS). When your brain gives a command to the skeletal muscle, the stimulus is sent from the CNS to the muscle via nerve cells or neurons. The stimulus causes a release of chemicals called neurotransmitters which stimulate the skeletal muscle to contract.
Some diseases and disorders can affect skeletal muscle movement and action. For example, if there is damage to the neurons or muscles themselves then there can be problems with both voluntary and involuntary actions. Other diseases such as muscular dystrophy and multiple sclerosis are autoimmune disorders which means the body’s natural defenses (in this case antibodies) attacks and destroys the body’s own cells i.e.
in this case the skeletal muscles.
Part 2 What Happens to Our Muscles as We Age?
As we age, there are a number of changes that can occur in our bodies. One of these changes is the loss of skeletal muscle mass and strength. This is referred to as sarcopenia. Sarcopenia can be caused by a number of factors such as: age-related changes in anabolic hormones, sedentary lifestyles, disuse, and poor nutrient intake. The best way to combat age-related changes in anabolic hormones, disuse, and poor nutrient intake is by following the advice given in the Big Three of Exercise: Resistance Training, Cardiovascular Training, and Stretching. The following is advice to combat a sedentary lifestyle.
Even if you follow the Big Three of Exercise, a sedentary lifestyle can cause sarcopenia. It is important to note that inactivity doesn’t just mean that you spend the majority of your day sitting down. Even if you exercise on a daily basis, but spend most of the rest of the day sitting (such as at a desk or in a car) then you are still being sedentary. In addition to the Big Three of Exercise, it is also important to break up periods of sitting or reduce the amount of time spent sitting.
Breaking up sitting time can be as easy as getting up and moving around every 30-60 minutes. Other ways to reduce sitting time is to park further away in the parking lot, taking the stairs, and walking around while talking on the phone.
Another age related factor that can cause sarcopenia is disuse. Disuse is also known as a muscle atrophying due to lack of stimulation. This means that if you are used to using a particular muscle or group of muscles on a regular basis and you stop using that muscle then the muscle will start to waste away or atrophy. For example, people who use wheelchairs will experience atrophy in their leg muscles if they don’t do their prescribed exercises.
As a result, it is important for those who use wheelchairs, crutches, or any other mobility aid to continue their prescribed exercises and routines.
Something that can cause both disuse and poor nutrient intake is a poor diet. It is important to have a balanced diet in order to combat sarcopenia. A diet deficient in calories, protein, or certain vitamins and minerals can lead to sarcopenia. Eating a balanced diet and supplementing as needed can help to slow the effects of sarcopenia.
In addition to diet and exercise, it is also important to get adequate sleep. Sleep deprivation has been linked to a decrease in muscle mass. Adequate sleep is defined as 6-8 hours per night for adults.
It is also important that you maintain a positive attitude and have a good sense of humor. Studies have shown that depression can contribute to sarcopenia due to a decrease in physical activity as well as changes in the hormonal profile.
Lastly, it is important to make sure that you get the right amount of nutrients through your diet. A lack of certain nutrients can cause health issues that can contribute to sarcopenia. The following are some nutrients that should be monitored depending on your age and activity level: Calcium, Vitamin D, Protein, and Vitamin B12.
Also, it is important to keep in mind that certain medications can also increase your risk of sarcopenia. Some drugs used to treat diabetes can lead to peripheral nerve damage and a loss of muscle mass. Other drugs, such as statins, inhibit the body’s ability to synthesize cholesterol and this inhibits the production of steroid hormones (such as testosterone). It is very important to keep a list of all your medications and any side effects that they may have.
This list should be brought with you whenever you see your doctor and should be taken into consideration whenever you have a physical or lab work is being done.
As mentioned before, sarcopenia can be caused by a number of factors and this can lead to a vicious cycle. The following are some common issues that can cause sarcopenia or make it worse:
Using a walker, wheelchair, or any other mobility aid on a regular basis.
Previous history of an illness or condition that affected your ability to move around or walk such as: Polio, Arthritis, Stroke, or Accidental Injury.
Significant Muscle Wasting Due to Lack of Nutrients, Poor Diet, or Lack of Blood Supply.
Lack of Use or Disuse. This is more commonly seen in the elderly and can be combated with regular exercise.
Certain Medications and their Side Effects such as: Statins and their inhibition of cholesterol synthesis, Diabetes Medications and their negative effects on nerves, Endocrine Medications and their effects on hormonal levels.
Sources & references used in this article:
Keeping older muscle “young” through dietary protein and physical activity by DR Moore – Advances in nutrition, 2014 – academic.oup.com
Dietary implications on mechanisms of sarcopenia: roles of protein, amino acids and antioxidants by JS Kim, JM Wilson, SR Lee – The Journal of nutritional biochemistry, 2010 – Elsevier
Apoptosis, autophagy, and more by RA Lockshin, Z Zakeri – The international journal of biochemistry & cell …, 2004 – Elsevier
No longer going to waste by K Garber – 2016 – nature.com