Kilpatrick, Marcus W. Ph.D., FACSM,; Rodriguez, Carlos M.D.
Recent data indicate that about one half of all Americans use a prescription (Rx) drug monthly, with one fifth of adults reporting taking three or more Rx drugs (2). These numbers represent significant increases from 20 years ago (2) and do not include the use of over-the-counter (OTC) medications, in which sales have ballooned to about $15 billion dollars annually (1). These figures coincide with increased efforts to “prescribe” exercise as a means of maintaining and improving health. Specifically, the American College of Sports Medicine and the American Medical Association teamed to launch the “Exercise is Medicine®” initiative. This initiative calls on patients and physicians to discuss the role of physical activity in disease prevention and medical treatment. The need for increased physical activity among all Americans and especially those individuals regularly taking medications is clear, and health fitness professionals will play an important role in making certain that exercise is safe and effective for Rx and OTC users. Therefore, the purpose of this article is to introduce pharmacological concepts and provide health fitness practitioners a guide to the impact of medications on the exercise response.
BASIC PHARMACOLOGICAL PRINCIPLES
Given the intricacies of drugs and how they impact human physiology, the abundance of terms with technical descriptions is not surprising. Although a high level of understanding is not a requirement for health fitness practitioners, a basic understanding of terms like those provided within Table 1 and the sections that follow empower the practitioner to access this important information more comfortably.
TABLE 1: Terminology...Image Tools
The control of pharmacological agents within the United States is managed by the Drug Enforcement Administration (DEA) and the Food and Drug Administration (FDA). The DEA is primarily concerned with the control of substances with a high potential for abuse and addiction. In contrast, the FDA functions to ensure the safety and efficacy of medications. The FDA also serves important roles in regulating which drugs are available by Rx only (or available OTC) and approves the development of generic drugs. Importantly, the FDA oversees drug approval and monitors drug-related side effects to ensure consumer safety. Collectively, these two agencies have authority and responsibility in promoting public safety and health with respect to pharmacological agents.
Formal administration of the pharmaceutical relates to how the medication enters the body. The most common delivery methods are listed and briefly described in Table 2. Routes of administration vary dependent on the characteristics of the medication. Some medications must be delivered through specific routes to achieve the desired effect because administration through alternative routes may result in drug metabolism and lessened drug potency, whereas other treatments can be achieved by using multiple methods. For example, pain may be treated via OTC oral medications such as ibuprofen, Rx cream medications such as naproxen, prescribed transdermal pain patches such as lidocaine, and intravenous medications such as hydromorphone. This example makes clear that medications come in a variety of forms, which provides numerous options for pain management, including new versions that can be delivered via lollipops! As such, delivery method is influenced by desired onset, speed of absorption, and other factors.
TABLE 2: Common Rout...Image Tools
The appropriateness of a pharmaceutical agent significantly depends on safety and effectiveness. Medications are described as being “indicated” when use is considered safe, appropriate, and effective. In contrast, medications are “contraindicated” when use is not recommended because of safety or other concerns. For example, angiotensin converting enzyme (ACE) inhibitors are indicated in the treatment of hypertension, but their use is contraindicated in women who are pregnant. Importantly, many drugs are approved for specific medical conditions but used in an “off-label” manner at the discretion of the clinician for the treatment of other conditions. Migraine sufferers, for example, are sometimes prescribed a variety of FDA-approved medications, including beta-blockers, diuretics, and antidepressants for the prevention of headaches. An issue closely related to safety is the presence of adverse effects, which are harmful and undesirable side effects of medical treatment. Increased awareness of common adverse effects from medications in general and specific medications represents a great opportunity for health fitness practitioners to better serve their clients and patients.
CATEGORIES OF PHARMACEUTICALS
Although the division and organization of pharmaceutical drug categories might be of some interest to health and fitness professionals, the focus within this article is the presentation of classes of drugs (some Rx and some OTC) that commonly are encountered by practitioners promoting physical activity. Special attention will be given to medications that alter the exercise response in ways that could impact fitness assessments and exercise prescriptions. The sections that follow provide a brief introduction to the various drug classes, whereas Table 3 serves as a quick reference for information related to their impact on important physiological responses.
TABLE 3: Quick Refer...Image Tools
A variety of drug classes are available to treat hypertension by regulation of contractile force and electrical activity of the heart, dilatation of the vasculature, and vascular blood volume. Importantly, many of these medications significantly impact heart rate (HR) and blood pressure (BP) and therefore require the attention of the health fitness practitioner. Four important types of medications within this category are diuretics, beta-blockers, calcium-channel blockers, nitrates, and ACE inhibitors. The best and perhaps most powerful example is provided by way of beta-blockers. These drugs function to reduce the activity of the sympathetic nervous system so as to reduce the stress on the heart. Utilization of beta-blockers significantly reduces both HR (20 to 30 BPM on average) and BP (reductions are variable) during exercise, which requires an adjustment to HR-based exercise prescriptions and increases the utility of ratings of perceived exertion in monitoring exercise intensity. Importantly, beta-blockers tend to increase exercise capacity in cardiovascular disease patients by way of reducing ischemia and subsequent chest pain. Such reductions in angina-related symptoms is in fact a primary goal of many cardiovascular medications, including calcium-channel blockers and nitrates, whereas ACE inhibitors and diuretics provide cardiovascular benefit by reducing plasma volume and overall cardiac stress.
Medications designed to lower blood lipids are among the most commonly prescribed drugs in medicine. Importantly, there are a variety of blood lipids that impact health including low-density lipoproteins (LDLs), high-density lipoproteins (HDLs), and triglycerides. LDLs and triglycerides are associated with increased cardiovascular risk and intravascular plaque formation whereas HDL is considered to be cardioprotective. One class of lipid medications commonly prescribed is the group referred to as “statins.” These drugs function to block an enzyme linked to the production of cholesterol. Importantly, the impact of statins on the physiologic response to exercise generally is limited and therefore not a major consideration for exercise prescription. One notable exception is that some patients taking statins experience occasional or persistent muscle soreness, discomfort, or weakness that could lead to a severe condition known as rhabdomyolysis. Patients who complain of unusual persistent muscle soreness should follow-up with a physician because these specific symptoms serve as contraindications for intense muscular activity.
Many pulmonary medications are classified as bronchodilators and function to open up the bronchial tubes within the lungs to allow for better flow of air. Beta-agonists are among the most common types of bronchodilators. These drugs bind to receptors in smooth muscle of the lungs, causing bronchodilation, and are formulated in both short-acting and long-acting versions. Short-acting versions take effect in minutes but dissipate quickly, whereas long-acting versions take longer to take effect but last for hours. As such, short-acting versions are considered “rescue” medications and used as needed before or during exercise, whereas long-acting medications are for prophylaxis (or prevention) and used daily. Asthmatics with mild symptoms typically use a short-acting bronchodilator approximately 15 to 20 minutes before initiating exercise to prevent more severe asthma symptoms during exercise, referred to as exercise-induced asthma or EIA. Anticholinergic medications cause bronchodilation by blocking chemicals that cause bronchial constriction. Notably, many contemporary pulmonary medications are combination drugs that include two agents from different pulmonary drug categories. These medications can have a significant impact on the ability to exercise, especially in asthmatics. In both asthmatics and nonasthmatics, beta-agonists and anticholinergics potentially can enhance athletic performance and their use in competition is restricted by many sanctioning organizations. With respect to normal exercise participation, individuals with asthma also are encouraged to include more purposeful warm-ups and cooldowns, limit or avoid exercise when cold-related symptoms are present, and to stop exercise immediately and use a short-acting bronchodilator (like albuterol) if asthma symptoms develop during exercise.
The class of drugs known as stimulants is characterized by their actions on the body that increase psychomotor activities such as wakefulness and alertness. These drugs typically are referred to in a general way as “uppers” because of the produced effects. Drugs categorized as stimulants include caffeine, nicotine, amphetamines, cocaine, and ecstasy. Given the illicit nature of many stimulant drugs, only caffeine, nicotine, and amphetamine-like medications used to treat attention-related disorders such as attention deficit-hyperactivity disorder (ADHD) will be considered here. Caffeine is a naturally occurring stimulant found primarily in food items such as coffee, tea, and cocoa but also is processed as an additive for products such as soft drinks and energy drinks. Similarly, nicotine is found naturally in most tobacco products and has been synthesized for inclusion in smoking cessation aids such as patches, gums, and electronic cigarettes. Unlike caffeine and nicotine, ADHD medications (e.g., Adderall, Ritalin) are available by Rx only but are taken widely by adults and function as powerful central nervous system stimulants. Each of these agents has significant addictive potential and can increase resting HR and BP acutely. One consideration related to caffeine consumption is that relatively large intakes can produce a variety of symptoms that could impact exercise participation, namely, feeling jittery (sometimes to the point of feeling panicked), dehydration, and emotional fatigue.
The pharmacological treatment of diabetes is varied and dependent on the specific type of diabetes mellitus that is present. Those with type 1 diabetes are insulin dependent and therefore receive some form of insulin therapy to help maintain their blood glucose within a normal range. Importantly, insulin can be administered using a variety of methods, and modern approaches tend to be less invasive and center on providing a plan that will maximize the ability of the patient to regulate blood glucose levels. Importantly, diabetics should avoid injecting insulin into the limbs before initiating an exercise session and should instead administer the injection to the abdominal region and limit abdominal or core-related exercise in the period after injection. Likewise, significant physical activity should be avoided during the time frame associated with peak insulin activity, which would be dependent on the preparation of insulin being used. It is clear, therefore, that patients with type 1 diabetes have much to consider, and informed health fitness specialists can be an invaluable resource for these individuals. In contrast to type 1 diabetes, most people with type 2 diabetes are not insulin dependent and instead tend to use a variety of oral medications to reduce and regulate blood glucose. These medications include subclasses such as sulfonylureas, biguanides, meglitinides, and thiazolidinediones. Each functions to increase insulin production, insulin sensitivity, and/or reduce formation of glucose in the blood but also have the potential side effect of inducing hypoglycemia. Practitioners working with diabetic patients are encouraged to be mindful of potential symptoms of hypoglycemia, including hunger, dizziness, confusion, nervousness, and weakness. Such symptoms are possible for any diabetic medication but more likely with insulin therapy and sulfonylureas. In addition, although diabetic medications tend to have a limited impact on the exercise response, patients with diabetes must plan the onset, duration, and intensity of exercise carefully because of the insulin-like effect of exercise.
Weight Loss Medications
Drugs designed to combat obesity are available both by Rx and OTC. These medications work through a variety of mechanisms but typically exert their effects by reducing appetite, increasing metabolism, or reducing caloric absorption from food. Among the most popular weight loss drugs is orlistat, which is available OTC as Alli and by Rx as Xenical. Recently, the FDA approved two new Rx weight loss drugs, Qsymia (phentermine/topiramate) and Belviq (lorcaserin). Clinical evidence suggests that each of these drugs produces at least modestly beneficial results but do so with a range of side effects, most of which arerelatively mild. Similarly, a wide range of OTC nutritional supplements are available and represent big business for health food and supplement stores, but there are ongoing concerns related to the efficacy and safety of these products. Importantly, practitioners should ask clients and patients to report their use ofany weight-regulation medication so that prescription of exercise can be handled in the safest manner possible because some of these agents can impact the cardiovascular response modestly.
Drugs used to treat pain and inflammation are diverse and used in a wide variety of settings for aches, pains, and arthritis-related symptoms. Primary pain medication classes are acetaminophen, nonsteroidal anti-inflammatory drugs (NSAIDs), steroids (or corticosteroids), and opioids. Although practitioners may encounter individuals treating pain by way of steroids and opioids, these individuals likely are dealing with pain intensities that prevent participation in regular aerobic exercise. In contrast, practitioners routinely will encounter individuals seeking professional help from individuals taking Rx or OTC medications. As such, the focus here will be on acetaminophen and NSAIDs. The primary distinction between these two drug classes is that acetaminophen helps to manage pain, whereas NSAIDS have the ability to combat both pain and inflammation. The most common NSAIDs available OTC include aspirin, ibuprofen, and naproxen. Likewise, both groups of medications also are available in higher dosages via Rx. Although these groups of medications are known to provide significant pain relief, they also are linked to many side effects including problems related to the kidneys, gastrointestinal tract, and blood clotting. One relatively new form of NSAID is a group of medications referred to as COX-2 inhibitors. One such drug is Celebrex (celecoxib), which is more selective in its location of action and therefore tends to produce fewer side effects in efforts to treat joint pain. Importantly, these medications do not tend to impact the exercise response but can impact the ability to exercise, and awareness regarding client and patient usage is advised.
SCOPE OF PRACTICE
An important consideration for health fitness professionals is recognition of the potential limitations related to their education, knowledge, credentials, and experiences in pharmacology. Practitioners are encouraged to engage in ongoing formal or informal education on this important issue that impacts patients and clients in part because the increasingly professional nature of employment linked to exercise science demands knowledge in this area. However, health fitness professionals are advised to seek the counsel of a physician or other appropriately trained clinician when the issue is complex or seems likely to have important health-related impacts. That is, practitioners should work within the scope of their training and make certain that their role within any organization is defined clearly. This structure allows practitioners to provide the best possible counsel and care to members, clients, and patients.
TREATMENT COMPLIANCE ADVOCACY
One additional consideration for health fitness practitioners is their role as an advocate for compliance with physician orders related to drug usage or other clinical recommendations. This issue is important given research data suggesting that patient compliance with physician recommendations related to filling and properly using Rx and OTC drugs is quite poor (3). The personal relationship that often exists between the practitioner and client or patient provides a unique opportunity to facilitate improved compliance with prescribed pharmacological therapies. These relationships are built primarily around practitioner expertise related to exercise and fitness, but the presence of a personal relationship allows the practitioner to be well positioned to provide social support and guidance that can generate great benefit. Practitioners with a base of knowledge related to pharmacology can engage their clients and patients on the extent of their use of Rx and OTC drug usage, which can create a significant pill burden or polypharmacy situation that increases the risk of adverse effects. More generally, practitioners with a measure of knowledge and competence related to pharmacology can assist the patient in recognizing signs, symptoms, and side effects linked to medication usage and noncompliance with drug therapy. Importantly, practitioners should consider their individual skill sets and existing employer guidelines when making decisions about their scope of practice with respect to discussing pharmacological topics with patients and clients. However, it is noteworthy that an encouraging word from a trusted professional to take medications according to labels and physician orders and to report any challenges related to medication compliance represents another avenue for health fitness professionals to make a difference in the life and health of the people they serve. As such, knowledge related to pharmacological concepts further demonstrates the importance of the health fitness practitioner in promoting health and fitness within our society.
A very clear reality is that the daily work of the health fitness practitioner is evolving toward the expectation that the practitioner is knowledgeable about clinical issues such as pharmacology. These changes are linked significantly to the increased professional profile within our field. Embracing these changes requires continued commitment on the part of our excellent practitioners to be involved proactively in the health and wellness of the patients and clients encountered on a daily basis. This article serves to continue movement toward the goal of healthier people and communities, a worthy goal that reflects our important profession.
Smart Phone Resources
A variety of smart phone applications designed to provide basic information about prescription drugs are now available through the iTunes App Store and the Android Market. Two popular low- and zero-cost options include PocketPharmacist and Epocrates Rx.
CONDENSED VERSION AND BOTTOM LINE
Health fitness practitioners routinely provide services to individuals taking a wide variety of prescription and over-the-counter medications. Increased knowledge regarding terminology, drug categories, and impacts on the exercise response is important to daily professional practice. This article aims to provide an overview that empowers practitioners with knowledge that will allow for improved skill in working with a wide range of populations.
© 2014 American College of Sports Medicine.