Hypertension and exercise
Editted by HANNGILL 2009.2.6.
§ What Is Hypertension?
Blood pressure (i.e., the force exerted by blood against the arterial walls) is indirectly measured with a sphygmomanometer or blood pressure cuff.
Blood pressure is determined by how much blood the heart pumps and the resistance to blood flow.
Systolic pressure (SBP) is produced as the heart ejects blood during ventricular systole.
Diastolic pressure (DBP) is created during ventricular relaxation (i.e., the period in which the ventricles fill with blood) (Powers and Howley, 1996).
A normal blood pressure reading for a person at rest is 120/80mmHg for males and 110/70mmHg for females.
Hypertension is defined as blood pressure equal to or greater than 140/90mmHg. Hypertension, or high blood pressure, is defined as a reading of 140/90 on three consecutive measurements at least six hours apart.
( The definition varies for pregnant women, where hypertension is defined as 140/90 on two consecutive measurements six hours apart. )
Thus, hypertension can result from either increased systolic pressure (the first number of the two values), diastolic pressure (the second number) or both.
An increase in either raises the risk of medical complications, thus the higher the increase, the greater the risk .
Individuals with a blood pressure reading over 160/95mmHg have a 150 to 300 % higher annual incidence rate of coronary artery disease (CAD), chronic heart failure, intermittent claudication and stroke than individuals with normal blood pressure .
Hypertension is generally classified into one of two categories: essential and secondary.
Although the cause of essential hypertension is unknown, it is believed to develop in individuals with certain hereditary variations in genes.
In contrast, secondary hypertension is a consequence of a known etiology (i.e., disease process), thus results from another disease (e.g., renal artery stenosis, coarctation of the aorta, adrenocortical or benign tumors and hypokalemia) ..
In the United States and Canada, an increase in blood pressure typically occurs as people age.
This elevation is not caused by age itself, however, but instead by what typically goes along with age, such as additional body weight (most of it fat), decreased daily physical activity, high intake of salt or animal products and stress.
More than 7.5 million Canadians and 50 million Americans have been diagnosed as having high blood pressure, or hypertension. Over many years, hypertension is a major cause of strokes, heart attacks, congestive heart failure and kidney failure. Also, recent data indicates that having even moderately elevated blood pressure, over time, increases the risk of dementia in old age.
This elevated pressure, termed hypertension, has been referred to as the ''silent killer'' because it is not recognized by a given set of symptoms or subjective feelings. As such, hypertension may be even greater as many individuals choose not to have regular physical exams and/or blood pressure checks.
The incidence is higher among African Americans, Mexican-Americans, Puerto Ricans, Native Americans and Cuban-Americans as well as individuals with lower educational and economic backgrounds.
Consistently high blood pressure causes the heart to work harder than it should and can damage the coronary arteries, the brain, the kidneys, and the eyes. The effects of hypertension include strokes and heart attacks.
This astounding statistic is due in large part to various contributing factors,
such as smoking, a diet rich in fat and cholesterol, and stress.
In 95 percent of hypertension cases, the cause is unknown.
Experts are aware of contributing factors that increase the chances of developing hypertension,
but no one has been able to determine a direct link between the factors and developing high blood pressure.
§ Gauging blood pressure
For blood to flow from the heart and lungs throughout the body, it needs to be under pressure. Each time the heart beats, it sends blood all over the body through the circulatory system. As the heart contracts, the pressure in the arteries increases; as the heart relaxes between beats, the blood pressure decreases.
Normal resting blood pressure in apparently healthy individuals averages 120/80 mmHg.
The first number, 120, represents the pressure against the artery walls when the heart contracts (systolic blood pressure).
The second number, 80, is the pressure against the artery walls during the resting phase (between heart beats) and is termed diastolic blood pressure.
The difference between these two pressures, the Mean Arterial Pressure, or MAP, represents the average blood pressure throughout the arterial system.
Specialized pressure sensors throughout the body regulate blood pressure and ensures it doesn't fall too low, thus compromising adequate flow to tissues; or doesn't rise too high, thus increasing the work of the heart and stressing vessels. Generally, blood pressure is regulated in such a way that it rises and falls consistently with the demands of the body.
Occasionally, blood pressure control mechanisms malfunction or are unable to compensate for the demand placed on the body. one of the resulting conditions is hypertension.
§ Effects of Hypertension
Hypertension kills! Hypertension ,
if uncontrolled, causes damage to various organs in the body resulting to other diseases.
The organs usually affected are the following.
1. Heart ? leads to heart attack and heart failure
2. Brain ? leads to stroke and internal bleeding
3. Kidneys ? leads to renal failure and the need for dialysis
4. Eyes ? leads to blindness
5. Peripheral Blood Vessels ? leads to peripheral vascular
diseases like limping (claudication) and tissue death (gangrene).
§ Diet and Hypertension
Sodium intake has been a primary target for hypertension control, though it is ranked fourth as the lifestyle factor associated with hypertension. About 50 percent of individuals appear to be "sodium sensitive." This means that excessive sodium intake tends to increase blood pressure in these groups of people, and they do not appear to excrete excessive amount of salt via the kidneys.
Sodium-sensitive individuals include the elderly, obese individuals, and African Americans.
The Dietary Guidelines for Americans recommend that adults consume no more than 2,400 milligrams of sodium daily.
There are a number of ways to limit sodium in the diet, including:
Do not use salt at the table
Check food labels for sodium content
Choose unprocessed foods
Limit processed meats and cheeses
Limit pickled meats and vegetables
Limit salty snacks
Limit intake of soy sauce, BBQ sauce, and other condiments and foods that may be high in sodium
Potassium supplements (2?4 grams daily) have been shown to moderately decrease blood pressure.
Fruits and vegetables are excellent sources of potassium.
The Dietary Guidelines for Americans recommend that adults consume at least 3,500 milligrams of potassium daily.
A diet high in fruits and vegetables has been linked to a decreased risk of both hypertension and stroke.
Foods high in omega-3 fatty acids have positive effects on hypertension and cardiovascular disease by relaxing arteries and thinning the blood.
In addition, several studies have demonstrated that individuals with hypertension may benefit from daily doses of calcium (800 mg) or magnesium (300 mg).
§ Exercise and Hypertension
The current intensity recommendation for hypertensive individuals is to use low to moderate intensity exercise.
Research shows that low to moderate intensity (60-80% of MHR Maximum Heart Rate) aerobic exercise can lower systolic blood pressure by 5-25 mm Hg and diastolic blood pressure by 3-15 mm Hg in mild to moderate hypertensive individuals. Regular physical activity has also been shown to be effective in reducing the relative risk of developing hypertension by 19 to 30 percent.
Conversely, a low cardio-respiratory fitness in middle age is associated with a 50 percent greater risk of developing hypertension. Results have been similar in both men and women.
It is import!!ant to remember that the key to a successful exercise program is consistency over time.
Endurance activities such as walking, swimming, cycling and low-impact aerobics should be the core of the exercise program.
( Exercises that include an intense isometric component that can cause extreme and adverse fluctuations in blood pressure should be avoided.)
As aerobic conditioning improves, add low resistance, high repetition weight training. Remember, light weights at first, progress gradually.
Circuit training is preferred over free weights.
During weight training, holding one's breath should be avoided because it can result in large fluctuations in blood pressure and increase the potential of passing out or, in some individuals, possibly result in life threatening events such as abnormal heart rhythms. 不整脈, arrhythmia
Ideally, hypertensive individuals should exercise five to six times per week depending on their initial fitness level. However, improvement can be achieved with as little as three sessions per week.
The total exercise duration should be in the range of 30 to 60 minutes per session.
People with lower levels of fitness should start with shorter durations (10 to 15 minutes) and gradually (5 minute increments every 2 to 4 weeks) increase to the 30- to 60- minute goal.
§ Blood Pressure Responses During Exercise
Dynamic exercise: isotonic contraction
(which consists of alternating muscle contraction and relaxation, such as in walking, running and cycling)
During dynamic exercise, the systolic rate should rise steadily as the intensity of the exercise increases, while the diastolic rate should change very little. For example, in a healthy person performing vigorous exercise, his or her blood pressure might jump from 120/80 at rest to 160 to 220 / 75 at the most intense part of the exercise.If the systolic rate becomes greater than 240, doesn't increase as the intensity of the exercise increases, or drops below resting level, then the cardiovascular system is not responding appropriately and the exercise should be stopped.
If the diastolic rate increases by 20 above the resting value, or reaches 120, the exercise should be stopped.
Static (or heavy resistance) exercise: isometric contraction(in which the muscle contraction is held for more than a few seconds before relaxing, such as in strength training and isometric exercise).
When an exercise causes a muscle to use more than about 25 percent of its strength, such as during heavy weight lifting, the pressure within the muscle increases and causes the small blood vessels (arterioles and capillaries) in the muscle to collapse. When this happens, oxygen-rich blood cannot reach the muscle. Reducing the amount of blood flowing to the working muscle during static or heavy resistance exercise can cause temporary pain in the muscle.
This lack of oxygen, called tissue hypoxemia, causes a rapid increase in both systolic rate and the diastolic rate throughout the contraction. It is believed that this increase in blood pressure is the body's attempt to get oxygen to the working muscles by forcing open the arterioles.
The speed and magnitude of the rise in the systolic and diastolic rates are greater as the intensity of the contraction increases and as the duration of the contraction lengthens.
(This does not happen, however, if the contraction lasts for only a few seconds or if there is a rest period of at least a few seconds before the muscle is contracted again.)
The higher blood pressure rapidly increases the workload on the heart and can cause an inadequate amount of blood to flow to the heart muscle (myocardial ischemia) in patients with coronary artery disease.
Also, the very high blood pressure reached during vigorous sustained muscle contractions could cause a stroke or the splitting of the aortic wall (where there currently is a weakness) in patients already at risk.
( aorta =the main artery)
Exercisers should be careful to avoid holding their breaths during the contraction phase of the exercise.
Called a "valsalva maneuver耳管通氣法," holding the breath during a sustained muscle contraction reduces blood flowing back to the heart, resulting in a decreased amount of blood the heart has to pump and potentially limiting the quantity of blood flowing to the brain.
Exercisers should remember to exhale on the exertion (or lifting) phase and inhale upon the relaxation (or lowering) phase.
Research shows that physically active men and women have lower average blood pressures and are diagnosed less frequently with hypertension than their sedentary counterparts.
The minimum amount of activity associated with lower blood pressure appears to be 30 to 60 minutes per day at a moderate intensity level plus a gradual warm-up and cooldown.
People with established hypertension should use exercise in conjunction with other forms of treatment, including antihypertensive medication, and should avoid sustained heavy resistance or isometric exercise and highly competitive situations involving vigorous exercise.
Also, those with hypertension are prone to sudden drops in blood pressure following exercise. This can cause fainting, so gradual cooldowns are very import!!ant.
§ Why exercise lowers high blood pressure
*Regular exercise reduces blood pressure by increasing circulation to the muscles and skin. So, hypertension exercise reduces the heart’s workload which reduces blood pressure.
*Widens arteries.
*It improves functioning of the kidneys & the body’s ability to manage and eliminate excess fluids. Hypertension could result from the body’s retaining water.
*Finally, exercise usually leads to fat loss and fat/weight loss is strongly linked to improved blood pressure.
§ Recommended cardiovascular exercises:
*Brisk walking (5-7 kmh)
*Bicycling (at 16 kmh. or less)
*Canoeing or rowing (at about 5-6 kmh)
*Swimming at a comfortable pace
*Low or high impact aerobics like stepping
*Gardening
*Dancing
*Home care and repair
*Golf (walking the course)
*Fishing
*Tai Chi or *Qi Gong reduce high blood pressure
*Relaxation exercises like meditation is a good hypertension exercise
§ Hypertension Exercise Cautions
* Stage 3 hypertension must be treated with medication before initiating exercise therapy.
* Blood pressure-lowering drugs, such as alpha-blockers, calcium channel blockers, and vasodilators may cause blood pressure levels to drop after abruptly ending exercise.
* Beware of the heat. Using blood pressure-lowering drugs, such as beta-blockers should make you cautious of developing heat illness when exercising.
* As always, please consult with qualified medical personnel to eval!!!uate your health & for specific recommendation on exercising with high blood pressure.
* Please, be patient, start slowly and gradually increase frequency & duration.
* Overweight & obese adults with high blood pressure should combine regular exercise and weight loss to effectively lower resting blood pressure.
* Emphasize non weight-bearing activities, as most hypertensive are obese or elderly.
* Isometric exercises should be avoided until hypertension is stabilized because contractions can cause extreme spikes of blood pressure
* Resistance training is not recommended as a primary form of exercise for people with hypertension.
It can be used as part of an overall workout program including cardiovascular exercise, but not solely on its own.
* Light endurance activities like walking, swimming, cycling and low-impact aerobics should be stressed.
* Do some Yoga exercises for hypertension such as, Surya Namaskar Asana, Santulam Asana, Pawanmukta Asana, Uttanpada Asana and Shava Asana (this is a very beneficial Asana for HBP).
* As conditioning improves, add low resistance, high repetition weight training. Remember, light weights at first, progress gradually.
* During weight training, never hold your breath. Avoid exercises that require lifting weights above the head ie. Shoulder press.
* one should Maintain exercise intensity below 80% MHR. Evidence exists that exercise intensity above this does not produce beneficial effects on blood pressure.
* Stop exercising if you feel weakness, dizziness, chest pain or discomfort in your neck, arm, jaw or shoulder, and seek medical assistance.
* Warm up for no less than 5-10 minutes to ensure an appropriate preparation for the cardiovascular system. This ensures no sudden changes in blood pressure.
* Cool down for 5-10 minutes to prevent dizziness, light-headedness and fainting.
Hypertension exercise should be followed by an extended cool-down period.
* Remember to exhale on the exertion (or lifting) phase and inhale on the relaxation (or lowering) phase.
*Exercise five to six times per week depending on initial fitness level. However, improvement can be achieved with as little as three sessions per week. The total exercise duration should be between 30 to 60 minutes per session.
*Even a single exercise session provides an immediate reduction in blood pressure that can last for up to 22 hours
§ To help prevent hypertension, note the following recommendations:
Know your blood pressure - the higher it is, the more frequently it needs to be checked
Avoid becoming overweight, or lose weight if your body mass index (BMI : weight kg / stature 2 cm ) is greater than 25.
Perform moderate physical activity 30 to 60 minutes five days a week or more
Limit alcohol intake to no more than two drinks per day
Restrict sodium intake (table salt)
Increase dietary potassium and calcium intake
Move toward a plant-based diet and reduce consumption of animal products (meat, cheese, eggs)
Develop skills to deal with stressful situations
*** Body Mass Index Calculator ***
§ Medication
Although antihypertensive drugs reduce blood pressure, some may also dampen exercise performance. Hypertension control through beta-blockers and, to a lesser degree, the calcium antagonists diltiazem and verapamil, reduces the heart rate response to sub-maximal exercise. Beta-blockers blunt exercise-mediated increases in heart rate and cardiac output (Q) and may reduce exercise performance. This reaction is more pronounced with non-selective beta-blockers (e.g., propranolol). Conversely, dihydropyridine (i.e., derivative calcium antagonists) and direct vasodilators may increase heart rate response to sub-maximal exercise (ACSM, 1996). Vasodilators, alpha-adrenergic blocking drugs and calcium channel blockers do not suppress cardiac output or exercise capacity.
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★ 당뇨병과 운동 Diabetes and Exercise ★
당뇨병 과 운동 Diabetes and Exercise - by HANNGILL This symbol has been used to represent diabetes since March 2006 § 당뇨병(糖尿病, diabetes mellitus) 당뇨병은 insulin 작용의 부족에 의하여 고혈당증을 보이면서 탄수화
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The available data suggest that moderate-intensity (40~70% VO2 max) aerobic exercise is associated with a significant reduction of blood pressure in hyper-tensive and normo-tensive participants and in overweight, as well as normal-weight participants. Interestingly, increasing exercise intensity to above 70% VO2 max did not have any additional impact on blood pressure reduction.