Millions of Americans currently take prescribed medications to manage various chronic conditions making it imperative for personal trainers to understand the side effects of medication and exercise implications to guide our clients safely and effectively.

According to data released in 2012 by the National Center for Health Statistics, 30% of adults ages 65 and older are currently taking beta blockers for heart disease; over 40% regularly rely on cholesterol-lowering medications; 15% are medicated to keep diabetes under control. Trainers will inevitably encounter clients living with health conditions that require maintenance drugs.

Understanding the Bounds of Beta Blockers

The therapeutic effect provided by beta-blockers tends to create an altered physiological response to exercise. The mechanism of this medication blunts the usual increases in heart rate and blood pressure that accompany higher-intensity workloads.

The fact that beta-blockers attenuate the heart rate response to exercise means traditional methods for establishing target heart rate are likely to be invalid. Therefore, the most important program component for individuals taking a beta-blocker is the use of an alternative method for setting target intensity.

The rate of perceived exertion (RPE) scale is an excellent option. Likewise, because beta-blockers can mask the usual symptoms of hypoglycemia in individuals with diabetes, it is incumbent upon trainers to strongly encourage these clients to regularly check blood glucose values prior to beginning a workout session to ensure levels are in a safe range.

Diabetic clients may carry portable glucometers with them at the gym, checking blood sugar levels during and after training. These periodic readings can indicate how the client’s system is responding to the volume and intensity of the exercise program. Once you both get a feel for how much blood glucose values fluctuate depending on the format of the session, monitoring may not be required quite as often.

Paying Attention to Pain Management

Muscle relaxers are another commonly prescribed class of medications. Many individuals rely heavily upon these drugs to make conditions such as fibromyalgia and rheumatoid arthritis more manageable. Understanding how challenging it is for these clients to even attempt exercise while living with chronic pain is key when designing training programs.

While most of the medications in this category are highly effective for pain, muscle relaxers come with potentially serious side effects. Blurry vision, “brain fog”, and a very dry mouth are often reported. If a client seems more dehydrated than usual while exercising, he may find it challenging to push himself to the level of your expectations. Rather than allowing him to leave the gym feeling inadequate, knowledge of this potential pitfall can enable you to make time for frequent hydration breaks during the hour session.

Blurred vision can hamper coordination, an important consideration when performing lateral movement patterns or lifting weights. Periodically checking in with the client to assess his comfort level with the workout design allows the trainer to make any necessary on-the-spot alterations.

Hormones and Energy

Female clients who use birth control pills or hormone replacement therapy may be unaware of hidden side effects that interfere with the body’s response to exercise. Ongoing use of female hormones often causes a drop in blood levels of B vitamins. This, in turn, has a direct impact on the body’s liver function, energy systems, and lactate production, all of which serve a vital role in exercise performance and recovery. While many women may not disclose such information in their new- client assessment, lower energy levels than typically expected might be a red warning flag to decrease intensity or volume.

Cholesterol Conundrum

Statins are by far the most commonly prescribed medication for treating high cholesterol. Such maintenance drugs bring on the age-old debate of which is worse, the situation being treated or the medication’s side effects? Cholesterol-lowering drugs are notorious for causing muscle aches, even in the absence of a significant workout session.

Clients who choose to soldier on might need reminding that they can likely experience more discomfort during a workout, plus increasingly sore muscle groups during recovery. While the client’s first inclination is to ease back on his efforts in the gym, a well-informed personal trainer can create programs that are challenging enough to effect success while leaving ample time for extended cool-down stretches at the end of the hour.

Danger To The Kidneys

Occasionally, statins have been associated with exertional rhabdomyolysis, a condition in which damaged muscle tissue releases protein myoglobin into the bloodstream upon being broken down, posing a significant threat to kidney function.

Cases of exertional rhabdomyolysis are most often observed in deconditioned individuals who attempt to engage in high-intensity resistance training and eccentric exercises, especially when performed in a hot, humid environment such as a summer outdoor Boot Camp class.

Ways to help clients on statins avoid exertional rhabdomyolysis:

  1. Embark upon aerobics and strength training at a reasonable pace for deconditioned clients, observing their reactions and progressing gradually and appropriately.
  2. Talk to clients about the signs and symptoms of exertional rhabdomyolysis, most notably muscle stiffness/pain, atypical fatigue and very dark, almost brown, urine.
  3. Schedule any summer outdoor training sessions in the early morning or later in the evening, when temperatures are coolest.
  4. As always, encourage clients to adequately hydrate before and during training, continuing to drink fluids later in the day.

Potential Balance Issues

Medications that are prescribed in the treatment of depression and anxiety often interfere with one’s ability to successfully engage in strength training. While highly effective, once again we see side effects serious enough to warrant discussion. According to the CDC, the most commonly reported side effects of such drugs include dizziness, impaired judgment, fatigue, and lightheadedness. All of these can throw off a client’s sense of balance, which is a necessary part of many standing exercises in a typical strength-training workout.

If a client has disclosed this aspect of his medical history, a program can be designed that makes more use of machines than free weights and excludes exercises that place him in an inverted position, either supine or prone.

How Innocuous are Over-the-Counter Meds?

The commonly held yet dangerously false public perception regarding the safety of over-the-counter (OTC) medications often leads to overdosing. While we know that prescription drugs are designed to be taken exactly as prescribed, many athletes suffering sore muscles or clients with chronic pain are inclined to up the ante when medicating with acetaminophen or aspirin-containing products. This is why aspirin is the leading cause of liver toxicity in the United States.

Organ poisoning is not the only reason for concern. Excess consumption of OTC painkillers containing these ingredients may adversely affect a workout session. Aspirin interferes with the body’s natural clotting process, presenting a problem in the case of an injury sustained while training or participating in contact sports. Aspirin also blocks the brain’s pain-signaling mechanism. In so doing, a pulled muscle or fractured bone may not register as serious enough to seek treatment; thus, continuing the workout session can take a minor injury to a significantly higher level.

The Acetaminophen Trap

Indeed, acetaminophen is the most widely used pharmaceutical analgesic and antipyretic agent in the United States and the world. Tylenol is the most ubiquitous name brand of acetaminophen.

While acetaminophen is quite safe and effective when taken in appropriate dosages, it is reported by the American Association of Poison Control Centers to be one of the most common pharmaceuticals associated with both intentional and unintentional poisoning.

Acetaminophen poisoning is the most common cause of hepatic failure requiring liver transplantation in Great Britain. In the United States, such poisoning has replaced viral hepatitis as the most common cause of acute hepatic failure, and is the second leading cause of liver failure requiring transplantation.

Accidental overdoses of Tylenol and other products containing acetaminophen account for a staggering 40 to 50 percent of all cases of acute liver failure each year in the United States alone. Robert J. Fontana, M.D., Associate Professor of Internal Medicine at the University of Michigan Medical School and Medical Director of liver transplantation, endorses Tylenol as a safe drug. However, he is quick to add, “….like most other things in life, too much of a good thing can be bad for you.”

When headache or backache pain is severe, it is common for individuals to disregard the dosage warnings printed on the label of the pain reliever containing acetaminophen and self-medicate as they see fit, often taking twice the recommended amount of the medication.

The prevailing notion is that if a product does not require a prescription, it must not have severe side effects. Nothing could be further from the truth; according to Brian Strom, director of the Center for Clinical Epidemiology and Biostatistics at the Perelman School of Medicine at the University of Pennsylvania, any product on the drugstore shelves that contains an active ingredient can “interfere with normal bodily functions”. In the case of acetaminophen, those effects can prove to be deadly.

Just how does such an overdose occur? A perfect illustration comes in the form of a man battling upper respiratory flu. Several common over-the-counter preparations designed to ease coughing and sneezing can contain upwards of 500 milligrams of acetaminophen per dose. If the individual also wishes to alleviate his headache and body aches, taking Tylenol on top of this other medication can easily put him into a possible toxic range.

In addition, someone for whom a prescription medication has been prescribed for post-operative pain might also reach for a Tylenol dosage to further ease the discomfort. It does not take much to accidentally overdose, with potentially far-reaching effects.

Acetaminophen is primarily metabolized by the liver. Too much of the drug ingested at one time can overwhelm the liver conjugation process, causing a build-up of a toxic metabolite as the body is forced to process the drug via alternate pathways. Necrosis then occurs in the liver as well as the kidney tubules. Individuals with a history of alcohol abuse may be even more susceptible to liver damage from acetaminophen overdose. For this reason, the Food and Drug Administration currently recommends that individuals consuming more than three alcoholic beverages per day should refrain from taking acetaminophen or other over-the-counter pain medications.

While it should seem fairly clear that taking too much of any over-the-counter product could possibly result in toxicity symptoms, consumers have come to consider acetaminophen such a familiar product, one that has been marketed for decades, and therefore might assume that the medicine is completely safe. The fact that Tylenol, for example, is widely available in very large quantities (e.g., 500 tablets per bottle) no doubt only serves to reinforce this perception.

In July of 2011, Johnson & Johnson announced that it was reducing the maximum daily dose of its Extra Strength Tylenol pain reliever to lower risk of accidental overdose from acetaminophen, its active ingredient. The company’s McNeil Consumer Healthcare Division will be changing the labels on Extra Strength Tylenol packages to list the maximum daily dose as six pills, or a total of 3,000 milligrams, down from eight pills a day, or 4,000 milligrams.

McNeil also reduced the maximum daily dose for its Regular Strength Tylenol and other adult pain relievers containing acetaminophen. Medical providers, too, might begin to promote awareness and provide greater education to their patients before prescribing even readily available painkillers.

While these measures are being put into place for the safety and well-being of the consumer, they are only going to prove effective if the public learns to adhere to the dosage recommendations. If we think of the information printed on the labels as being just as important as a doctor’s orders written on a prescription pad, perhaps we would not be as willing to risk self-medicating.

Being aware of the potential risks involved in taking as little as one additional tablet over the listed dosage can go a long way in preventing accidental overdoses. Our bodies are just complex machines, after all, and are designed to strive to maintain homeostasis at all costs. When those processes are significantly disrupted, the effects can be very dangerous indeed.

Part of being a quality personal trainer is doing the work required to truly get to know your clients, before initiating training. By familiarizing yourself with his health history and especially any maintenance drugs he takes, you can design safe, effective workouts while keeping a careful eye on potential side effects.

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Hillcrest, Laurence. “Expert Warns of Overuse of Over-The-Counter Pain Medication.” Medical News Today. MediLexicon, Intl., 13 Mar 2006

Brian Strom, MD, Perelman School of Medicine at the University of Pennsylvania

Lee W. “Drug-induced Hepatotoxicity”. New England Journal of Medicine, July 31, 2003; 349:474-485.

Michael J Ameres, MD, Consulting Staff, Department of Emergency Medicine, Southampton Hospital.

Daniel Crough, MD, Consulting Staff, Department of Emergency Medicine, Southampton Hospital. 8.

Cathleen Kronemer

Cathleen Kronemer is an NFPT CEC writer and a member of the NFPT Certification Council Board. Cathleen is an AFAA-Certified Group Exercise Instructor, NSCA-Certified Personal Trainer, ACE-Certified Health Coach, former competitive bodybuilder and freelance writer. She is employed at the Jewish Community Center in St. Louis, MO. Cathleen has been involved in the fitness industry for over three decades. Feel free to contact her at She welcomes your feedback and your comments!