Epidemiological, mechanistic, and practical bases for assessment of cardiorespiratory fitness and muscle status in adults in healthcare settings

Abstract

Given their importance in predicting clinical outcomes, cardiorespiratory fitness (CRF) and muscle status can be considered new vital signs. However, they are not routinely evaluated in healthcare settings. Here, we present a comprehensive review of the epidemiological, mechanistic, and practical bases of the evaluation of CRF and muscle status in adults in primary healthcare settings. We highlight the importance of CRF and muscle status as predictors of morbidity and mortality, focusing on their association with cardiovascular and metabolic outcomes. Notably, adults in the best quartile of CRF and muscle status have as low as one-fourth the risk of developing some of the most common chronic metabolic and cardiovascular diseases than those in the poorest quartile. The physiological mechanisms that underlie these epidemiological associations are addressed. These mechanisms include the fact that both CRF and muscle status reflect an integrative response to the body function. Indeed, muscle plays an active role in the development of many diseases by regulating the body’s metabolic rate and releasing myokines, which modulate metabolic and cardiovascular functions. We also go over the most relevant techniques for assessing peak oxygen uptake as a surrogate of CRF and muscle strength, mass, and quality as surrogates of muscle status in adults. Finally, a clinical case of a middle-aged adult is discussed to integrate and summarize the practical aspects of the information presented throughout. Their clinical importance, the ease with which we can assess CRF and muscle status using affordable techniques, and the availability of reference values, justify their routine evaluation in adults across primary healthcare settings.

Serum Levels of Myonectin Are Lower in Adults with Metabolic Syndrome and Are Negatively Correlated with Android Fat Mass

“…Skeletal muscle secretes myokines with autocrine, paracrine or endocrine action on multiple physiological processes, such as metabolism, inflammation, and muscle development [ 1 , 2 , 3 ]. Serum levels of myokines are affected by conditions such as exercise and diet, and likewise, their levels influence the state of health and disease [ 2 , 4 ].…”

Independent and joint associations of cardiorespiratory fitness and lower-limb muscle strength with cardiometabolic risk in older adults

“…We believe that some aspects could partially explain the disagreement between ours and previous findings. Although grip strength and chair stand tests are valid and reliable measures of muscle strength [ 9 , 21 , 49 ] there is poor agreement using grip strength and chair stand tests to identify older adults with low muscle strength [ 50 , 51 ]. These differences between the assessment methods and their implications for muscle strength may also account for some of the discrepancies between the results from our study and previous investigations.…”

“…As limitations, this is cross-sectional study, which precludes to establish a cause-effect relationship of cardiorespiratory fitness and muscle strength with cardiometabolic risk. Although we have used validated tests to assess cardiorespiratory fitness and muscle strength [ 9 , 18 , 22 , 23 , 49 ], they are not considered “gold-standard”. In addition, 30-s chair stand test is a specific proxy of lower-limb muscle strength.…”

“…In addition to CVD risk algorithms such as MetS and ICH, physical fitness is a strong predictor of cardiometabolic health [ 9 ]. Aging reduces cardiorespiratory fitness and muscle strength [ 10 , 11 ] and both low cardiorespiratory fitness and muscle strength are independently associated with increased cardiometabolic risk in older adults [ 12 , 13 ].…”

What Can One Minute of the Day Tell about Physical Activity?

“…CRF reflects the integrated ability of the body to transport oxygen from the atmosphere to the mitochondria in cells of skeletal muscles to perform physical work [6]. Higher CRF levels are associated with better cardiovascular function, including increased cardiac output, improved blood flow, and better oxygen delivery to working muscles [6]. This allows the body to efficiently meet the increased demand for oxygen during strenuous activity [7].…”