Chapter 3 Section 4 Exercise as Medicine

Section 3 

Exercise as Medicine

Exercise is Medicine®

Exercise is Medicine® is a global health initiative, managed by the American College of Sports Medicine, with the objective to make physical activity assessment and promotion the standard of clinical care. Resources for clinicians can be found at https://www.exerciseismedicine.org/eim-in-action/health-care/health-care-providers, including action guides for health care professionals and patient handouts. The safety of exercise, screening for exercise risk, and behavioral strategies are addressed as well. Foundational exercise prescriptions, recommendations for thirty specific medical conditions, and guidance for returning to exercise after COVID-19 infection can be found at the Exercise is MedicineÒ website.

Why does exercise impart such a wide range of health benefits to the human body?

Exercise has pleiotropic effects on the human body – the cardiovascular, pulmonary, musculoskeletal, endocrine, neurologic, metabolic, and immune systems respond to exercise in an integrated manner. If stimulated regularly, adaptations in these systems lead to, for example, improved cardiorespiratory fitness, increased muscle mass, decreased adipose tissue mass, improved glucose regulation, reduced cancer risk, and increased resilience, to name a few (https://www.nhlbi.nih.gov/events/2020/nhlbi-and-niddk-workshop-exerkines-health-resilience-and-diseases-executive-summary). One could conduct a literature search using the keywords “exercise” or “physical activity” with a clinical condition or disease prevention topic, and population and likely hit on a number of publications.

For example, a search in PubMed (https://pubmed.ncbi.nlm.nih.gov/ accessed June 18, 2023) using “exercise” or “physical activity” AND “chronic kidney disease” AND “adult” yielded 105 publications in the past year alone. How is it that physical movement can have such wide-ranging effects? There is no simple answer to this important question. One potential explanation lies with the exerkines, signaling molecules that are released by tissues in response to acute exercise or exercise training (i.e., chronic regular exercise) that may explain tissue-to-tissue communication (Chow et al., 2022; Safdar et al., 2016) as well as individual differences in the responses to exercise (Sarzynski et al., 2022).

Some exerkines are known to originate from skeletal muscle, white adipose tissue, brown adipose tissue, blood vessels, liver, brain, bone, and immune cells (Chow et al., 2022; Robbins & Gerszten, 2023). More exerkines, their source(s), and target tissues will be discovered. Exerkines may be cytokines, peptides, nucleic acids, lipids, or metabolites that exert autocrine, paracrine, or endocrine effects (Safdar et al., 2016). Examples of exerkines include interleukin-6 (IL-6) released from skeletal muscle, adiponectin from white adipose tissue, nitric oxide within the endothelium, and brain-derived neurotrophic factor (BDNF) within the brain and skeletal muscle (Chow et al., 2022). New exerkines and their functions are identified using molecular-level analytical tools such as metabolomics, proteomics, and RNA sequencing in human and pre-clinical models.

Although some experts challenge the importance of exerkines, this research is a shift in exercise science from a single outcome measure to inter-organ markers that induce an integrated response to exercise (https://www.nhlbi.nih.gov/events/2020/nhlbi-and-niddk-workshop-exerkines-health-resilience-and-diseases-executive-summary; (Chow et al., 2022; Robbins & Gerszten, 2023)). The on-going Molecular Transducers of Physical Activity Consortium (MoTrPAC) study (https://motrpac.org), funded by the National Institutes of Health (NCT03960827), is a multi-site study to discover and begin to characterize the cellular and molecular changes that occur in response to acute exercise and exercise training (resistance or aerobic) in sedentary, otherwise healthy, adults, acute exercise responses in highly active adults, and in children with low or high physical activity habits (Sanford et al., 2020). The findings of the MoTrPAC study will advance understanding of the mechanisms underlying the health benefits of exercise and launch a new era of exercise research.

Summary

The nurse practitioner in primary care has the opportunity to encourage sedentary patients to become physically active, to affirm the exercise habits of physically active patients, and to act as a proponent of aerobic and resistance exercise to all patients. This chapter is an introduction to exercise science and the epidemiology of exercise and physical activity.