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It is recommended that adults over age 35, who never have exercised before, obtain medical clearance. This is necessary for protection of individual’s health and from any fitness professional’s legal perspective. Also, questionnaire consent/waiver form in Appendix A should be completed for further legal protection and for medical doctor's perusal.
VALUE OF A STRESS TEST
A stress test should be completed by all mature adults and individuals age 35 or older who are sedentary. Individuals who possess one or several coronary risk factors, such as high HDLs, a smoker, high BP, or if individual has not seen a physician within last 5 years should undertake a stress test.
A stress test becomes even more crucial for those over 65 as it is difficult to determine over 65's tolerance for activity. It also is necessary to determine presence or absence of myocardial ischemia (a temporary deficiency of blood supply to heart caused by an obstruction), either prior to an exercise program, while in relatively good health, or as a post-coronary test to indicate damage levels and a therapeutic program. A stress test is not a substitute for complete history and yearly physical examinations, but it is a viable test that can pick up on problems that would preclude a person's participation in an exercise program or indicate required modification of a program in accordance with physical problems.
Fitness professionals or physicians should explain in advance to individual to be tested what is involved. This helps to increase motivation and for individual to exercise for longer and with less anxiety. The individual will need to:
-Wear proper clothing (tracksuit) and comfortable running or walking shoes.
-Refrain from eating for 2-3 hours prior to test, so that digestion does not interfere with optimal blood flow.
-Refrain from smoking for at least 1-2 hours, since smoking can impair cardiovascular capacity.
WHAT OCCURS The stress test conducted by physician can be performed with a motorized treadmill, bicycle or arm ergometer. Often if individual suffers from lower body maladies, or if a return to work after an illness involves strenuous upper body activity, arm ergometer may be used to produce a more accurate test.
The stress test is designed to challenge body to a safe but necessary level to reveal irregularities that are unlikely to show when at rest. Usually an undiagnosed heart disease appears only during vigorous exercise. The narrowed coronary arteries may supply enough blood to resting individual, but, as oxygen needs rise, electrocardiographic abnormalities indicate a problem. The physician will look for evidence of ischemia and its effects in rhythm disturbances (tachyarrhythmias or bradyarrhythmias), aortic and mitral valve disease, significant hypertension, and myocardial disease.
The stress test usually will not take more than 10 minutes. Exercise for longer will measure endurance rather than aerobic capacity (VO2max). During any physical activity, body responds as follows:
-Heart rate increases
-Systolic BP increases
-Diastolic BP remains same or decreases
-Cardiac output increases
-Systemic vascular resistance decreases
-Coronary blood flow increases
-Myocardial O2 demand increases
The client is tested at 85-90% of predicted maximal heart rate, although some doctors do not advance test this far as they feel it is unnecessary to do so – usually as a safety precaution. Doctors even may stop test once client reaches his or her target heart rate. There is one serious drawback to this approach. There is variability in maximal heart rate of individuals within each specific age group. For example, predicted heart rate of a 60-year old at 85% maximum heart rate is approximately 132 bpm. Because there is a standard deviation, some individuals being in better health and others in worse health for any age group, or at least less tolerant to exercise strain, it is possible that some people may have a maximal heart rate well above or below 132 bpm. If an individual's heart rate is above or below age-specific level, result will be unreliable in that it is difficult to determine safety or severity of test. The strain may not be enough, or too much. Therefore, it is necessary for physician to motivate client safely to his or her limits to determine proposed intensity of exercise program, and for client, or client’s personal trainer, to know at what level body was stressed sufficiently.
