Many clinicians treating Medicare patients come to expect to see various telltale characteristics of aging, including sarcopenia. This condition is characterized by loss of muscle mass and strength, visceral fat gain, tight muscles, slowed metabolic rate, osteoporosis, slowed nerve conduction, and slowed reflexes.
Starting With the Basics
Sarcopenia is the term used to refer to age-associated loss of muscle mass and function leading to a host of negative health outcomes such as reduced functional capacity, falling, fractures and all-cause mortality.1 Primary sarcopenia is caused by aging itself, whereas secondary sarcopenia describes sarcopenia that is caused by disuse (immobility or physical inactivity), and by conditions out of a person's control – think advanced organ failure, malignancy and neurodegenerative disease.2
Sarcopenic obesity (SO) is the coexistence of sarcopenia and obesity. It's much more dangerous than sarcopenia or obesity occurring separately.
Assessment and Physical Function Testing: Three Criteria
Muscle mass, muscle strength and physical function should all be considered when assessing the degree of sarcopenia. An advanced approach to measure muscle mass (and fat mass) can be best acquired from computed tomography (CT), magnetic resonance imaging (MRI), or whole body dual-energy X-ray absorptiometry (DXA), but this is not always practical due to high cost and limitations in availability.
Muscle strength is best measured by handgrip strength using a handheld dynamometer. This isometric grip strength test has been widely used due to its simplicity, low cost, ease of use, and strong predictability of all-cause mortality.3 An additional cost-effective and simple approach, used to test functional leg strength, is the 30-second chair stand test. All that is needed is a 17-inch-high chair without arm rests and a stopwatch to record the number of times the patient can sit and rise to a full standing position in 30 seconds.
Although there are a wide range of tests to gauge physical function, gait speed appears to be ideal due to simplicity, ease of measurement and high predictability of mobility limitations and all-cause mortality.4 This test simply assesses comfortable walking speed measured in meters per second over a short distance.
Pathogenesis
There is strong evidence of a causal association between fat gain and diminishing strength. Based on my years in clinical practice, I have observed that obesity and poor muscle mass are more likely to be co-occurring than expected by chance alone. An increase in fat mass and decrease in muscle mass at a rate of 3-8 percent per decade after the age of 30 years contributes to a steady decline in physical function.5 As expected, when someone advances in age, the quantity of visceral fat and intramuscular fat infiltration increases, contributing to impaired muscle function.
Copious ectopic fat has been shown to clinically upregulate pro-inflammatory cytokines and adipokines.6 This chronic inflammatory response then perpetuates metabolic complications including poor glycemic control and insulin resistance that interfere with muscle function. In addition, hormones such as GH, testosterone and IGF-1 decline (as one ages and gains peritoneal fat), leading to a loss of protein muscle synthesis. Inadequate nutrition, primarily insufficient protein, can contribute to depressed muscle mass and strength.
When I conduct 24-hour food recalls on patients, I notice more people (regardless of age) relying on high-carbohydrate, high-calorie, low-nutrient convenience foods for their meals and neglecting good-quality protein that is vital for optimizing muscle protein synthesis.
"Yo-yo" or "crash" dieting is the practice of repeatedly losing weight by caloric restriction and subsequently regaining it.7 This is a detrimental approach to losing weight for many reasons, most notably because of the muscle loss that occurs with each successive weight-loss phase. Yo-yo dieting also impairs metabolism, interfering with the body's ability to stay at a healthy and manageable weight.
Another lifestyle contributor commonly found in a Westernized society is physical inactivity. A sedentary lifestyle increases the risk of developing a plethora of chronic diseases, especially sarcopenia.
Lifestyle Interventions
The primary prescription to prevent and slow down sarcopenia is increased physical activity, particularly weight-bearing exercises; and increased protein consumption from whole-food sources.
Exercise Essentials: The ideal fitness plan consists of activities that incorporate strength training with resistance, endurance, flexibility, balance and coordination. I have referred many patients who just started to exercise to facilities that offer beginner fitness programs such as Curves, YMCA and SilverSneakers (for those ages 65 and older).
The main component of any effective program is circuit training, which can be customizable to any fitness level and physical limitation. Recommended weight-bearing exercises that can be easily demonstrated and prescribed include the following, subject to any patient functional limitations/restrictions:
- Lifting weights in a circuit format
- Walking / sprinting intervals
- Hiking
- Climbing stairs
- Dancing
- Jumping rope
- Step aerobics with ankle / wrist weights
Nutritional Considerations: Dietary protein and essential amino acid ingestion increase muscle protein synthesis rates and inhibit protein breakdown. High-quality protein sources include: whey protein shakes (when convenient), whole eggs, lentils, chickpeas, chicken, turkey, fish, dairy and lean meats. Spreading the protein intake throughout the day in 4-6-ounce servings per meal, combined with other macronutrients (25-30 grams), is a good strategy.
The current recommended dietary allowance for protein is 0.8g/Kg/day; for example, a 150-pound person would need to consume 56 grams of protein per day. However, this guideline is less than optimal for maintaining muscle mass and strength, especially in those at risk for sarcopenia.
There are many nutritional supplements that claim to aid in muscle protein synthesis. Creatine monohydrate (CM) appears to be the most studied, safe and efficacious. Creatine is a compound made naturally in the body (from amino acids, arginine, methionine and glycine) that provides and replenishes ATP for energy. Food sources such as dairy, meat and fish are rich in creatine; however, supplementing with CM can maximize the amount our muscles can store, resulting in greater muscle growth and repair.
When older adults supplement with CM while engaging in higher-intensity intervals of weight-bearing and/or endurance exercising, muscle protein synthesis is enhanced. The beneficial effects of increased muscle strength, muscle mass and power from CM make it an ideal supplement for those at increased risk of developing sarcopenia.
References
- Stenholm S, Harris TB, Rantanen T, et al. Sarcopenic obesity: definition, cause and consequences. Curr Opin Clin Nutr Metab Care, 2008 Nov;11(6):693-700.
- Choi KM. Sarcopenia and sarcopenic obesity. Korean J Intern Med, 2016 Nov;31(6):1054-1060.
- Bouchonville MF, Villareal DT. Sarcopenic obesity – how do we treat it? Curr Opin Endocrin, Diabetes, and Obesity, 2013;20(5):412-419.
- Goisser S, Kemmler W, Porzel S, et al. Sarcopenic obesity and complex interventions with nutrition and exercise in community-dwelling older persons--a narrative review. Clin Interv Aging, 2015 Aug 6;10:1267-82.
- Lutz CT, Quinn LS. Sarcopenia, obesity, and natural killer cell immune senescence in aging: altered cytokine levels as a common mechanism. Aging, 2012 Aug;4(8):535-46.
- Bano G, Trevisan C, Carraro S, et al. Inflammation and sarcopenia: a systematic review and meta-analysis. Maturitas, 2017 Feb;96:10-15.
- Lee DC, Shook RP, Drenowatz C, Blair SN. Physical activity and sarcopenic obesity: definition, assessment, prevalence and mechanism. Future Sci OA, 2016 Jul 14;2(3):FSO127.
Dr. Louis Miller, a 2000 graduate of New York Chiro-practic College, also attained an MS in applied clinical nutrition. He is the owner / operator of Advanced Chiropractic of South Florida and Healthy Weight Solutions.