Exercise and Hypertension - safe management means moderation.

Hypertension is the most common form of cardiovascular disease in the United States. Conservative
estimates suggest that one in every three adults have high blood pressure. Hypertension is defined as
resting systolic and diastolic pressures greater than or equal to 140 and 90 mm Hg, respectively (1,2). A
pre-hypertensive state is now thought to exist with pressures greater that 120/80 (12). It is influenced by
many factors including family history (#1), age, gender, race, body fat, kidney function, muscle mass, and
cardiovascular fitness level (1,2). During exercise the list is expanded to include many neural, hormonal,
and local factors that affect the internal vessel pressure. A basic physiological relationship exists that
defines blood pressure in the simplest of terms:
Since cardiac output is a major contributor, it is important to recognize that when heart rate or stroke
volume increases so does systolic and the corresponding mean blood pressure. This fact should be a
serious consideration during the prescription of exercise for the hypertensive client and will be explored
further in this article. The second primary component of the blood pressure formula is peripheral
resistance. Peripheral resistance comes in many forms. An easy way to think about blood pressure and
the effects of peripheral resistance is to think about the life of a garden hose. The cardiac output of the
heart reflects the force of blood rushing through the arteries of the body, much the same way a faucet
regulates the amount of water flowing through a garden hose. When the faucet is opened up completely,
the hose expands under the pressure of the water. The expansion is based on elastic properties within the
hose itself. The vessels of the body react the same way. When the cardiac output of the heart is high, the
amount of pressure on the vessel walls is equally high. So individuals with low fitness levels and
consequent high resting heart rates can expect an elevation in resting blood pressure as will individuals
experiencing elevations in heart rate in response to stress (physiological and psychological).
The ability of the vessels to expand is the first component to peripheral resistance. When the hose is aged
and suffers from sun exposure it becomes hardened, just like the arteries of the body. Toxins and other
contributors lead to arteriosclerosis or hardening of the arteries. When the hose, or arteries harden they
cannot compensate by expanding with pressure increases. This problem is compounded by
atherosclerosis, the plaque that builds up on the epithelial lining of the vessels. As the space inside the
artery reduces, the pressure increases. This can be illustrated by holding a thumb over the end of the
hose. The water projects outward in a direct stream because the pressure is increased in response to the
decreased circumference of the outlet hole. When an elevated heart rate is coupled with arteriosclerosis
and atherosclerosis, blood pressure can become a problem. The problem only gets worse when we add
in excessive physiological and psychological stress.
Exercise is certainly a physiological stress and increases blood pressure as previously illustrated.
Different types of exercise influence the amount of pressure within the vessels. Again the garden hose
provides an excellent example of the physiological response. When muscles contract they produce tension
force in combination with the compression forces upon the vessels, which add up to increased blood
pressure. This occurs in the same way, that, if you stand on a flowing garden hose the water will shoot out
of the hose further under the pressure of your body weight than when you are not standing on it. When
muscles contract dynamically they shorten and lengthen. The compression forces placed upon the vessels
are based on the level of intensity or load assigned to the movement, the ability of the body to release
pressure through changes in body posture, and the breathing techniques employed during the activity.
Exercises that require little force production show the lowest blood pressure response and are often aided
by vasodilation. Theses exercises are generally classified as cardiovascular or aerobic because they are
often performed for periods of time that initiate aerobic metabolism. Such activities include walking,
running, biking, swimming and rollerblading to name just a few. The majority of the blood pressure
changes during these activities come from increases in cardiac output.
On the contrary, weight training requires elevated force production in response to heavier load
assignments. The activities elicit much higher blood pressure responses because the compression forces
on the vessels limit expansion, while heart rate response is dramatically elevated based on the
physiological stress. Essentially, the hose is turned on full blast, while you stand on it, and hold your thumb
over the end. Exercises that require periods of isometric contractions, place the body in a compressed
position, and/or are performed under load, have drastic and often serious blood pressure responses. This
information is extremely important to the fitness professional because many hypertensive clients are
ignorantly placed in exercise regimens that appear to be safe because of the little skill required to perform
the movement, but in fact may be detrimental due to pressures associated with it.
There is more than enough scientific evidence to recommend that individuals with hypertension not
engage in, or perform activities that require extended periods of strenuous lifting, pushing, holding or
hanging movements (2,5). Any training that uses intense static contractions drastically increases the
oxygen needs of the heart and compresses the vessels. Shoveling snow, carrying heavy objects (boxes,
buckets etc.), squatting, leg pressing, bench pressing, and using many of the machine exercises will
cause potentially harmful elevations in blood pressure. When resistance training is used as part of the
training regimen the exercise selection should avoid these compressive type exercises as well as
activities requiring even partial isometric contractions. Resistance exercise for hypertensives should
mirror cardio respiratory training intensities; low resistance circuits, focusing on functionality and
movement patterns, are one example.
When exercise is used correctly it can actually become a champion in the fight against hypertension.
There is a considerable amount of evidence that endurance exercise can reduce blood pressure in
hypertensive clients. Sympathetic nervous system activation is reduced in individuals that engage in
regular endurance activity. This reduction is supported by an increased activation of the parasympathetic
nervous system, which lowers heart rate and reduces vascular resistance. At the same time the body
increases the elimination of sodium by the kidneys in response to the regular endurance-training regimen,
which in turn promotes fluid loss and a decrease in pressure (3,8). This is the same reason that reducing
salt intake is a good idea for the hypertensive client. Additional reductions in blood pressure come from
altered baroreceptor function. The decreased responsiveness of the receptors is likely due to
parasympathetic action and thus causes a reduced response to regulate blood pressure at higher values
(2). Additionally, some evidence suggests that atrial natriuretic factor, released from granules in cardiac
tissue into the circulation, causes the veins to relax, sodium to be excreted and more fluid to be released
by the kidneys (10,11).
These positive activities associated with exercise should excite the fitness professional training a
hypertensive client. Hypertension is a serious disease and has very few symptoms. It is so prevalent within
the American population that most personal trainers will have individuals with high blood pressure on their
client lists. This suggests that along with proper screening procedures and education, the client requires
proper exercise prescription, as well as diet and behavior modification. Personal trainers should routinely
measure a client's blood pressure and become familiar with the medications that their clients take for the
disease. The following suggestions should be reviewed for management of the disease and safe
participation in an exercise program.
Recommendations for the Hypertensive Client
· See a doctor before engaging in physical activity.
· Engage in regular physical activity (3x/wk 60-80% max HR).
· Regularly monitor exercise and resting BP.
· Avoid environmental stressors.
· Reduce body fat.
· Avoid high sugar foods - high plasma insulin concentrations stimulates sympathetic nervous ..system and
promotes sodium retention in the body.
· Reduce intake of sodium.
· Avoid stressful situations.