They say that 50 is the new 30, but that may not hold true for all your Baby Boomer clients. In fact, more than 50% of Americans 55 or older already have some degree of heart disease, according to the latest calculations from the American Heart Association (2006). Worse still, this percentage is expected to grow significantly in the future as the Baby Boomer generation nears retirement age.
Many of these seemingly healthy older people are your clients. As an exercise professional, you need to set appropriate exercise limits and encourage your clients to adhere to them. You also need to know when to refer a client to another health professional for further evaluation. The trick is determining which clients you can help and which you can better serve with a referral. This article examines the appropriate testing and assessment tools you can use to make that determination.
Stress Test Report
Typically, patients with heart disease undergo exercise stress testing on a routine basis, usually every year. The American College of Sports Medicine (ACSM) recommends that men over 45 years of age and women over 55 who wish to engage in vigorous exercise and who have more than one coronary disease risk factor (e.g., family history, cigarette smoking, high blood pressure, high cholesterol, impaired fasting blood glucose, obesity, sedentary lifestyle) first undergo an exercise stress test (ACSM 2006). (Older clients with one or fewer risk factors do not generally need a stress test but should at least have physician clearance!)
The stress test report gives you important information about the physiologic changes a client goes through during exercise. Unfortunately, not all exercise stress tests are conducted or reported equally well; some offer more information than you need in order to design
a proper exercise program, while others offer far less. Because the data is often
inadequate or inaccurate, it is vital to
establish and maintain communication with your client’s physician in order to glean other necessary information.
Evaluating the upper limits of a client’s exercise stress test will enable you to recommend safe and effective exercise guidelines. And through close supervision and necessary heart rate and blood pressure monitoring, you can encourage and reinforce the client’s adherence to these guidelines.
Maximum MET Level
A person’s capacity for exercise is measured in terms of METs, a metabolic equivalent unit used to estimate the metabolic cost of physical activity. This measurement is noted on the stress test report as “METs achieved.” Remember that 1 MET = 3.5 milliliters of oxygen consumed per kilogram of body weight per minute.
Clients with known cardiac history should exercise at 45%–85% of VO2max, defined as maximal oxygen consumption/uptake, which is measured in milliliters per kilogram of body weight per minute. The formula for target VO2 = (VO2 max – VO2 rest) (exercise intensity) + VO2 rest.
Be careful to interpret MET level data yourself. In many reports the stated MET levels have been achieved incorrectly, which can lead to overestimation of exercise capacity. Unless the entire stage of the protocol is completed, the MET level achieved by a client is that of the last completed stage.
Exercise levels that exceed 85% VO2 max require physician clearance because such levels can induce ischemia, the term for lack of blood flow to the heart. Ischemia can lead to chest pain, irregular heart rhythms, heart attack and ultimately death.
For more information on METs, please refer to “Using METs in Program Design” in the February 2006 issue of IDEA Fitness Journal.
The heart rate at which the heart is no longer receiving ample blood and other vital nutrients is called the ischemic heart rate. If ischemia is present, testing during an electrocardiogram (ECG) tracing will show changes in the ST segment; the ST segment lies between the end of the QRS complex and the initial deflection of the T-wave, as shown in Figures 1 and 2. Exercise physiologists recommend that if the stress test report states that the ST segment depression is greater than or equal to 1 millimeter, trainers set the maximum target heart rate 10 beats below the heart rate that correlates to the depression (ACSM 2006; AHA 2006).
Remember that the heart’s left ventricle pumps blood to the body. When this chamber’s ability to function has been compromised by a heart attack, muscles and other tissues are deprived of blood and oxygen. A common measure used to evaluate the heart’s ability to pump blood is the ejection fraction (EF). The EF is the percentage of blood pumped out of the heart per beat.
Typically, an EF above 50% is considered normal. However, a reported EF that is lower than 40% should raise a flag. Clients with an EF of less than 40% who wish to begin a traditional resistance training program (e.g., lifting weights greater than 50% of their one-repetition maximum, or 1RM) should first get physician clearance to do so.
Rate Pressure Product
Another important consideration for clients with suspected or confirmed
heart disease history is the rate-pressure product (RPP). The RPP is the product of peak heart rate and peak systolic blood pressure, which indicates the oxygen demands on the heart.
Because it reflects the heart’s oxygen demands, a client’s RPP can be used to mark if and when ischemia occurs. The RPP associated with the first signs of ischemia (ST segment depression) on the ECG is called the critical RPP. Unlike heart rate, ischemia will always occur at the same RPP, regardless of heart rate or systolic blood pressure value. Therefore, it would be wise to use RPP data gathered from the stress test report to design a client’s upper limits of exercise intensity ranges.
Keep clients well below the RPP value associated with ischemic changes on their ECGs. To monitor RPP, take regular blood pressure and heart rate measurements during the first several exercise sessions, along with periodic measurements after you have established that measurements do not fluctuate much and are acceptable.
Pacemakers or Implanted Cardiac Defibrillators
Clients who have devices such as pacemakers or implanted cardiac defibrillators (ICDs) may show blunted exercise heart rates during exercises that limit their upper-body movement. Some of these devices greatly reduce exercise capacity, while others do not. One way to know is to have clients perform lower-body exercise at a moderate intensity on a treadmill or cycle while you measure heart rate.
To determine the correct exercise intensity for clients with these implanted devices, use the rating of perceived exertion (RPE) scale. Encourage clients to perform extended warm-ups and cool-downs to avoid shortness of breath and premature fatigue.
Cardiac medications are another important consideration when designing an
exercise program. Prescription drugs can lower heart rate and blood pressure
responses and should be reviewed carefully. (For more information about cardiac medications, see “Cardiovascular Medication and Your Client” in the May 2006 issue of IDEA Fitness Journal.) In addition, exercise may be perceived as more difficult by individuals who take medication for type 2 diabetes (e.g., glipizide or glyburide) than by nonusers.
Training clients with heart disease requires close monitoring and supervision on your part as a trainer, but it can also sharpen your skills and expand your abilities as an exercise professional. With the burgeoning population of older clients, it can also be a training niche as you yourself age—and an endless revenue stream for the future!
Tom’s resting ECG shows no ST depression.
Tom’s peak exercise ECG (leads I, II, and III, respectively) shows 1.5 mm ST depression in lead II. Notice the downward slope of the ST segment.
American Heart Association (AHA). 2006. Heart disease and stroke statistics—2006 update. www.american
retrieved July 11, 2006.