Managing Age-Related Muscle Loss in Primary Care

Scene 1: Exercise Medicine Clinic, Rio de Janeiro, Brazil 
I just finished one evaluation on physical fitness and health and looked at my schedule. My next patient would be a 65-year-old man. How fit will he be? Will he have evident age-related muscle loss? I gave myself a short break and my mind went to the late 1970s. 
Once upon a time, the practice of medicine was based primarily on the skill of your physical examination, previous experiences, and your ability to reason logically and make solid deductions. In 1979, the stethoscope was part of my dress code. After one elective semester as a research fellow at the Ambrose Cardiorespiratory Unit at McMaster University Medical Centre, in Hamilton, Canada, where I was honored to witness the dawn of evidence-based medicine, I graduated from Federal University of Rio de Janeiro. I still remember being introduced to some promising novelties in cardiology, such as M-mode echocardiograms and myocardial scintigraphy. Radiology was primarily centered on x-rays, and lab testing was basic and poorly automatized.
Over the following decades, medical practice changed dramatically with the incorporation of new technologies. Recent advances in diagnostic tools, genetics, artificial intelligence, and sophisticated statistical analyses, along with well-collected scientific data, have molded how clinicians should think and work.
At the same time, clinical profiles also changed. Internists and primary care physicians are regularly managing patients who are, on average, older and have or are on the way to having potentially life-threatening chronic diseases, accompanied by poor lifestyle habits, and, highly important, often some degree of disability, frailty, and loss of independence. Many of them exhibit age-related muscle loss. 
Scene 2: Exercise Medicine Clinic, Rio de Janeiro, Brazil 
Conscious of the benefits of interrupting my sitting time with activity, I left my office and walked to meet my patient in the waiting room. I called his name and introduced myself. I watched how he listened and reacted to my speech, and how easy or hard it was for him to rise from the chair — readiness, velocity, and number of supports required: none, one, or two hands. I offered my own hand to him, and when we shook, I gauged the strength of his grip. 
I invited him into my office and took note of his somatotype and body composition, and whether he had any central obesity. Of course, and I should by no means miss this chance, I carefully observed how he walked in — his gait, speed, balance, posture — how he pulled up the chair, and how he managed to lower himself into his seat. Before I even sat in my own chair, I asked him if he remembered what his body weight was 5 years ago and what it was today. Before we got started in earnest, I had already managed to collect several pieces of relevant information. 
Muscle activity depends on muscle mass and function, and peaks somewhere between ages 25 and 35 before declining. The drop is slow in the early stages but accelerates rapidly after age 60 or 65.
Two of the most relevant variables in muscle function are strength and power. As a product of force and velocity, muscle power could be a more crucial factor than strength for many daily activities that demand movement against gravity or inertia, such as placing carry-on baggage in the overhead bin of an airplane or rising from the floor or chair.
The association between muscle mass and muscle strength or power is moderate, and physiologic data have indicated that the decline of muscle power with aging is faster and larger than that of muscle strength.
The term “sarcopenia” has become definitively incorporated into the medical glossary. From the Greek (“sark” and “penia”), sarcopenia was defined as reduced muscle mass, but more recently it has encompassed muscle strength in its definition. However, a recent consensus paper from the Global Leadership Initiative in Sarcopenia, using a Delphi approach, rejected the inclusion of muscle power in the concept of sarcopenia. On the other hand, a long time ago, some authors coined and advocated the use the term “dynapenia” to more precisely reflect the reduced levels of muscle strength and power that often accompany aging.
The best available intervention to counteract age-related deterioration of muscle activity is resistance exercise. The types of resistance exercises vary widely — by number of sets and repetitions, intervals between sets, speed of execution of movement, and percentage of maximal weight/load.
We recently proposed that, after an evaluation to identify the main muscle variable requiring attention, the resistance exercise program should be individually tailored and prescribed according to the objective to counteract sarcopenia or dynapenia.
What is more important for autonomy and better daily living conditions in old and very old individuals: muscle mass, muscle strength, or muscle power? More likely the response is muscle power — in practical terms, dynapenia rather than sarcopenia. This short video presents practical tips for obtaining optimal results in fighting dynapenia. The first choice should be power training or high velocity–based training, emphasizing two to three sets of six to eight repetitions performed as fast as possible (on the concentric or shortening phase of muscle contraction) with relatively high loads.
Internists and primary care physicians are most likely satisfied with the information they obtain by simple observation, and already can superficially grade the magnitude of a patient’s age-related muscle loss and its consequences to daily living.
However, those who want more objective information on nonaerobic physical fitness can add one to three simple tests to their consultation: the sitting-rising test (SRT); the 10-second one-legged test (10sOLS test); and the Flexitest. Poor performance on each of these — and particularly all three — is strongly associated with an increased risk for premature death in middle-aged and older individuals. These tests require no extra equipment and can be performed rapidly, and interpreting the results takes only a few moments using published reference values.
Age-related muscle loss profoundly affects our ability to sit and rise from the floor, so if time is limited, the SRT is the best assessment, as it measures all nonaerobic components of physical fitness. For a quick interpretation, consider that SRT scores vary from 0 to 10, do not substantially differ by sex, and that a composite score equal to or greater than 8 will reflect a minimum age-adjusted percentile of 61, most likely indicating relevant age-related muscle loss is not yet occurring.