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Chapter 07

Chapter 07. Physical Activity and Hypertension. Hypertension is defined in an adult as a blood pressure greater than or equal to 140 mm Hg systolic pressure or greater than or equal to 90 mm Hg diastolic pressure. American Heart Association recommended blood pressure levels

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Chapter 07

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  1. Chapter 07 Physical Activity and Hypertension

  2. Hypertension • is defined in an adult as a blood pressure greater than or equal to 140 mm Hg systolic pressure or greater than or equal to 90 mm Hg diastolic pressure. American Heart Association recommended blood pressure levels Blood Pressure Category Systolic (mm Hg)Diastolic (mm Hg) Normal less than 120 and less than 80 Pre-hypertension 120–139 or 80–89 High Stage 1 140–159 or 90–99 Stage 2 160 or higher or 100 or higher Physical Activity and Hypertension

  3. Hypertension • High blood pressure directly increases the risk of coronary heart disease (which leads to heart attack) and stroke, especially when it's present with other risk factors. • What Causes High Blood Pressure? • In 90 to 95 percent of high blood pressure cases, the cause is unknown. In fact, you can have high blood pressure for years without knowing it. That's why it's the “silent killer” — it creeps up on you. When the cause is unknown, you have what's called essential or primary hypertension. (source = AHA) Physical Activity and Hypertension

  4. Hypertension. Magnitude of the Problem • NHANES data - 37.5 million men and 38.8 million women 20 years or older, 33.6% of noninstitutionalized adults in the United States, have high blood pressure, defined as untreated systolic pressure of 140 mmHg or higher, or diastolic pressure of 90 mmHg or higher, • The prevalence of hypertension is disproportionately higher among African Americans, and it’s lower among Asian Americans, American Indians or Alaska Natives, and Mexican American men (see figure 7.2, next slide). Physical Activity and Hypertension

  5. Hypertension. Magnitude of the Problem Figure 7.2 • High blood pressure in Americans 20 years of age or older by sex and race. • Compared with whites, blacks develop hypertension at a younger age and have higher lifetime blood pressures, resulting in elevated relative risks that are 30% higher for nonfatal stroke, 80% higher for fatal stroke, 50% higher for heart disease mortality, and four times greater for end-stage renal disease Physical Activity and Hypertension

  6. High Blood Pressure Statistics • According to NHANES, more men than women have high blood pressure until age 45. • From ages 45 to 64, the rates in men and women are similar. • After that, the percentage of hypertension is much higher in women (see Table 7.2). Physical Activity and Hypertension

  7. High Blood Pressure Statistics • As with stroke, obesity, and diabetes, the prevalence of hypertension is highest in the southeastern region of the United States (Figure 7.3) Physical Activity and Hypertension

  8. Hypertension Risk Factors • Controllable risk factors • Obesity — People with a body mass index (BMI) of 30.0 or higher are more likely to develop high blood pressure. • Eating too much salt — A high sodium intake increases blood pressure in some people. • Drinking too much alcohol — Heavy and regular use of alcohol can increase blood pressure dramatically. • Lack of physical activity — An inactive lifestyle makes it easier to become overweight and increases the chance of high blood pressure. • Stress — This is often mentioned as a risk factor, but stress levels are hard to measure, and responses to stress vary from person to person. (Source = AHA) Physical Activity and Hypertension

  9. Hypertension Risk Factors • Uncontrollable risk factors • Race — Blacks develop high blood pressure more often than whites, and it tends to occur earlier and be more severe. • Heredity — If your parents or other close blood relatives have high blood pressure, you're more likely to develop it. • Age — In general, the older you get, the greater your chance of developing high blood pressure. It occurs most often in people over age 35. Men seem to develop it most often between age 35 and 55. Women are more likely to develop it after menopause. (Source = AHA) Physical Activity and Hypertension

  10. Hemodynamic Determinants of Blood Pressure. Etiology of Hypertension • Central Determinants • Heart Rate (HR) • Stroke Volume (SV) • Cardiac Output (CO) • Peripheral Determinant • Peripheral Vascular Resistance (PVR) Physical Activity and Hypertension

  11. Hemodynamic Determinants of Blood Pressure. Etiology of Hypertension • Central Determinants • Heart Rate (HR) • ↑ HR = ↑ BP; ↓HR = ↓ BP • Factors that ↑ HR = Increased metabolism (CO2 levels monitored by brainstem in cerebrospinal fluid), Stress (Sympathetic) Response (↑ epinephrine, norepinephrine), ↑ blood volume, ↑ venous return to the heart = (normal exercise response) Physical Activity and Hypertension

  12. Hemodynamic Determinants of Blood Pressure. Etiology of Hypertension • Central Determinants • Stroke Volume (SV) • ↑ SV = ↑ BP; ↓SV = ↓ BP • Factors that ↑ SV = ↑ venous return to the heart = (normal exercise response, “Frank Starling Effect” ), ↑ contractility (↑ epinephrine, norepinephrine, also increase with exercise as a sympathetic response), Note – Systolic blood pressure increases during exercise because of an increased HR and SV. Physical Activity and Hypertension

  13. Hemodynamic Determinants of Blood Pressure. Etiology of Hypertension • Central Determinants • Cardiac Output (CO) • CO = HR X SV • Anything that ↑ HR and/or SV will ↑CO • HR measured in beats per minute • SV measured in milliliters per beat • CO in measured in Liters per minute • CO = blood flow Physical Activity and Hypertension

  14. Hemodynamic Determinants of Blood Pressure. Etiology of Hypertension • Peripheral Determinant • Peripheral Vascular Resistance (PVR) • Is the resistance of the vasculature against the pumping force generated by the heart • Is resistance to flow • Is primarily generated by the diameter of the artery lumen (space where blood flows through the artery) Physical Activity and Hypertension

  15. Hemodynamic Determinants of Blood Pressure. Etiology of Hypertension • Peripheral Determinant • The smaller the diameter of the artery, the greater the resistance to flow. • Thus, PVR is mostly generated by the degree of vasoconstriction. • Vasoconstriction is caused by: ↑sympathetic drive (contraction of the smooth muscle cells in the arterial wall). This is a normal exercise response, that is countered by local vasodilatation from aerobic metabolites. It is not a normal resting response. Physical Activity and Hypertension

  16. Autonomic Nervous System • Increased sympathetic drive – increasing levels of epinephrine and norepinephrine • Effects of epinephrine and norepinephrine on heart rate and smooth muscle cells in arteries • Increase HR, SV, CO and PVR Physical Activity and Hypertension

  17. Physical Activity and Reduced Hypertension Risk: The Evidence Cross Sectional Studies • North Carolina • African American Adults • Odds ratio was 1.3x for inactive women compared to active women • After adjusting for other factors, odds ration was 1.6x Physical Activity and Hypertension

  18. Physical Activity and Reduced Hypertension Risk: The Evidence Cross Sectional Studies • Southern California • Caucasian Women • Age adjusted systolic and diastolic blood pressure in inactive women were 13 mmHg systolic and 6 mmHg diastolic higher. • After adjusting for other factors, there was an overall linear trend for lower blood pressure with higher levels of physical activity Physical Activity and Hypertension

  19. Physical Activity and Reduced Hypertension Risk: The Evidence Cross Sectional Studies • Seventh Day Adventists • African American subjects • Age/Sex adjusted systolic and diastolic blood pressure in inactive subjects were 10 mmHg systolic and 4 mmHg diastolic higher. • 42% of non-exercisers compared to 20% of exercisers were diagnosed as hypertensive. Physical Activity and Hypertension

  20. Physical Activity and Reduced Hypertension Risk: The Evidence Cross Sectional Studies • Active Commuting in Finland Four independent cross-sectional surveys of random national samples in Finland were carried out at five-year intervals from 1982 to 1997 as part of the Finnish cohort of the WHO MONICA study. Stratified by sex and 10-year age categories, high leisure-time physical activity but not activity for commuting was associated with lower DBP among both men and women. Physical Activity and Hypertension

  21. Physical Activity and Reduced Hypertension Risk: The Evidence Cross Sectional Studies • Active Commuting in CARDIA Associations were examined between walking or biking to work (self-reported time, distance, and mode of commuting) with cardiorespiratory fitness, leisure-time physical activity Men with any active commuting, compared to none, had a 50% reduction in odds of having a BMI ≥30 and had a DBP that was nearly 2 mmHg lower than in people who did not walk or bicycle to work Physical Activity and Hypertension

  22. Physical Activity and Reduced Hypertension Risk: The Evidence Prospective Cohort Studies • Aerobics Center Longitudinal Study • Relative risk for developing hypertension was 1.5 for the lowest fitness group • The lowest fitness group who had normal systolic and diastolic pressures had 10x the risk of developing hypertension than those that were highly fit and had normal blood pressures. Physical Activity and Hypertension

  23. Physical Activity and Reduced Hypertension Risk: The Evidence Prospective Cohort Studies • Aerobics Center Longitudinal Study • People who moved from the lowest fitness group to the highest fitness group had about ½ the risk of developing hypertension of those who remained in the low fitness group Physical Activity and Hypertension

  24. Physical Activity and Reduced Hypertension Risk: The Evidence Prospective Cohort Studies • Harvard Alumni Health Study • Those who expended less than 2000 kcal/wk had a 30% greater risk of developing hypertension than those who expended more than 2000 kcal / wk • There was an inverse relationship between participation in vigorous recreational sports in middle age and the risk of developing hypertension. Physical Activity and Hypertension

  25. Physical Activity and Reduced Hypertension Risk: The Evidence Prospective Cohort Studies • University of Pennsylvania Alumni Study • Those who spent less than 5 hours per week in sports participation had a 30% greater risk of developing hypertension. • Participation in vigorous recreational sports activity in middle age reduced the rate of hypertension Physical Activity and Hypertension

  26. Physical Activity and Reduced Hypertension Risk: The Evidence Prospective Cohort Studies • Iowa Women Study • The relative risk of developing hypertension was 30% higher in women in the lowest active group compared to the most active group Physical Activity and Hypertension

  27. Physical Activity and Reduced Hypertension Risk: The Evidence Prospective Cohort Studies • The Northwestern Trial • The incidence of hypertension in the control group (Sedentary) was 2x that of the intervention group. • Other intervention behaviors were not controlled, so the independent effect of exercise could not be measured. • Study showed the effectiveness of non-pharmacological intervention. Physical Activity and Hypertension

  28. Physical Activity and Reduced Hypertension Risk: The Evidence Prospective Cohort Studies – Youth Studies • New York City A cohort of nearly 200 mainly Hispanic 5-year-olds who regularly visited an inner-city medical center was followed for 20 months . Age-related increases in blood pressure were inversely related to higher fitness. Children in the top 20% of fitness gains had a significantly smaller increase in SBP (3 mmHg per year) compared to children in the lowest 20% of fitness gains (5 mmHg per year). Physical Activity and Hypertension

  29. Physical Activity and Reduced Hypertension Risk: The Evidence Prospective Cohort Studies – Youth Studies • The Northern Ireland Young Hearts Project Cardiovascular risk factors were assessed in a random cohort of 229 boys and 230 girls when they were 12 years old and again when they were age 15. There was a significant relation between self-reports of physical activity and lower SBP over the three-year period among boys but not girls Physical Activity and Hypertension

  30. Physical Activity and Treatment of Hypertension : The Evidence Strength of the Evidence • Summary: • Regular exercise decreases blood pressure; (SBP -11 mmHg ), (DBP -8 mmHg) • People with mild hypertension benefited more than those with more severe hypertension • Women had larger reductions than men (W=SBP -19; DBP -7 ) (M=SBP – 14; -5 mmHg) Physical Activity and Hypertension

  31. Physical Activity and Treatment of Hypertension : The Evidence Strength of the Evidence • Summary: • Consistent reductions in BP were found in studies that set exercise intensity below 75% VO2 max • The reductions in DBP were greater the longer the exercise training program lasted • People with mild hypertension benefited more than those diagnosed with severe hypertension or those with normal blood pressures. • Subsequent research has shown that men with severe hypertension can benefit from exercise intervention, and reduce Left Ventricular Hypertrophy Physical Activity and Hypertension

  32. Physical Activity and Treatment of Hypertension : The Evidence Strength of the Evidence • Summary: • A newer meta-analysis (See Figure 7.8, next slide)accumulated results of 72 randomized controlled trials of 3936 participants in 105 study groups who exercised mainly by walking, jogging, running, or cycling for at least four weeks • exercise training reduced systolic and diastolic pressures measured in a clinic by 3 mmHg and 2.4 mmHg, respectively • The reduction of resting blood pressure was more pronounced in 30 groups of patients with mainly stage 1 hypertension (−6.9 mmHg systolic and −4.9 mmHg diastolic) than in normotensive groups (−1.9/−1.6 mmHg)

  33. Physical Activity and Treatment of Hypertension : The Evidence Figure 7.8 Cumulative results of 72 randomized controlled trials of chronic exercise and hypertension.

  34. Physical Activity and Treatment of Hypertension : The Evidence Strength of the Evidence • Summary of additional interventions • A meta-analysis of 105 trials of lifestyle interventions lasting at least eight weeks on nearly 7000 adults with elevated blood pressure found that aerobic exercise compared favorably to dietary changes, as shown in Table 7.3. The evidence did not support the use of relaxation therapies or calcium, magnesium, or potassium supplements to reduce blood pressure

  35. Strength Of The Evidence • Temporal Sequence • Large cohort studies show lowered risk of developing hypertension following exercise • Strength of the Association • Collective findings show a 30-50% reduction in risk when active are compared to inactive • Consistency • Physical activity reduces blood pressure regardless of age, sex, or race. Physical Activity and Hypertension

  36. Strength Of The Evidence • Dose Response • No evidence of an intensity dose response; however, there is an effective intensity range • This range was 30-85% aerobic capacity • Duration of exercise 15-60 minutes • Frequency of exercise 3-4x / week, for at least four weeks. Physical Activity and Hypertension

  37. Strength Of The Evidence • Biological Plausibility • Possibly a reduction in plasma volume that decreases resting cardiac output • A reduction in resting catecholamines suggest that exercise training decreases the sympathetic drive lowering blood pressure via decreased HR and PVR • There is a relationship between blood insulin levels and hypertension, thus weight loss can promote a reduction in hypertension by reducing hyperinsulinemia • There may be a blunted sympathetic response to external stressors following exercise intervention Physical Activity and Hypertension

  38. END OF PRESENTATION Physical Activity and Hypertension

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