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EXERCISE and CARDIOFITNESS - A SUMMARY
Abstract: Cardiofitness is shown to be a major health risk factor, possibly more important than other major risks including smoking, cholesterol and blood pressure. A measurement of low Cardiofitness can identify a very high and presently unrecognized health risk. Although substantially dependent on regular amounts of adequately intensive exercise, Cardiofitness also is in part genetically endowed. Improvements in Cardiofitness potential from moderate and good regimes of cardiovascular exercise can add 5 and 10 years respectively to the Well-Days of life of our middle-age US population. There is a major need for the establishment and widespread dissemination of a standard and accepted HEF or equivalent method for the regular measurement of the Cardiofitness of individuals.
Exercise that produces improvements in cardiofitness reduces risk of Coronary Heart Disease, Stroke, all Cardiovascular Disease, and Cancer. Risks of these individual diseases now are related to Cardiofitness with good accuracy, and we have a similar reasonably accurate valuation of risk for death from all causes from Cardiofitness. As noted separately, the addition of separately obtained risks for heart diseases, stroke and cancer produces a result closely equivalent to that measured for all cause death rates. Thus we have a coherent picture of the importance cardiofitness and risk of individual major diseases and that for risk of death from all causes.
Low Cardiofitness can be a Major Risk: Most research on Cardiofitness has been focused on high heart rate exercise and the desirability of become highly 'fit.' This has overlooked what may be by far the most important need for understanding and measuring Cardiofitness:
This is the very high risks that accompany very LOW values of Cardiofitness. This key risk that today still is not measured medically may be the single most important risk factor that produce heart attacks that destroy life at those early years before age 50. This important risk is identified ONLY by Cardiofitness. It cannot be identified from differences in Activity Calories of exercise.
The results from population research studies provide only risk ratios for actual or estimated differences in the level of Cardiofitness. The Global analysis provided herein for Life Ahead suggests a much broader role for Cardiofitness. The average Cardiofitness for a sedentary man or woman at age 50 is 100 HEF by definition. Cardiofitness of groups of individuals moves downward from this value of 100 to 80 HEF for a person doing both no exercise and a minimum of physical activity, and to 70 HEF following prolonged bed rest. (See estimated distributions of fitness levels of populations derived from actual fitness measurements). These much lower than 'sedentary' levels of fitness produce extraordinarily high risk ratios. This is illustrated in the following table that shows the probable risk factors at differing levels of the HEF for major death from disease and death:
HEF Level Cardiovascular Disease Cancer Death,all Causes
% per HEF 5.40% 3.84% 3.52%
80 3.03 2.09 2.05
90 1.74 1.48 1.43
100 1.00 1.00 1.00
110 0.57 0.68 0.70
120 0.33 0.46 0.49
130 0.19 0.31 0.30
At the low fitness of 80 HEF the risk of heart disease and stroke is up 3 times, and risk of cancer and premature death is up more than twice. Multiply this further by the risk from just one more risk factor as cigarettes or high cholesterol and a heart attack can become a near certainty. Risks of smoking combined with sub-sedentary Cardiofitness produced coronary risk ratios exceeding 20 times in analyses of data from the large NY HIP study (Shapiro, Am J Public Health 59:June Supplement). Although the above table shows a maximum HEF of 130, HEF values above 150 were measured for the average of some most fit groups in the actual research studies. Although Life Ahead now credits a maximum improvement of 30 HEF from exercise, the actual research studies included individuals that had HEF values over this entire range. And there is no suggestion from the actual research data that benefits cease or even diminish at any specific level of the HEF.
Genetics are Involved: Cardiofitness although mostly determined by amount and level of physical activity and exercise is in part produced by genetics. The health-interested person may have an HEF 10 or more units lower or higher than average from genetics. Thus a person that is exercising faithfully still may have an HEF below 100. Thus there is no substitute for knowing our HEF level. Several methods are provided herein for obtaining at least an approximate measurement of this most important health factor, and much more about how to plan exercise effectively is provided herein. Life Ahead develops a genetic factor for Cardiofitness if results of a treadmill or other measurement are included, and accompanying recent exercise is fully entered and disclosed. If this factor exceeds +/- 10%, it is disclosed.
Cardiofitness and Well-Days of Life: Our 'Bottom Line' is "What will improvements in Cardiofitness contribute to our years of healthy life? With actual values of overall risk of death from HEF determined with good accuracy, it becomes quite straightforward to compute how HEF will affect the average length of life and Well-Days of life ahead. A fact of importance in this computation is research showing clearly that the risk benefits of improved Cardiofitness do not decline for men and women of older ages. The changes in Well-Days following are for the average man and woman with a starting HEF of 100 at age 50. Benefits can be even higher for those younger than this or those having unusually high present risks.
Differences in Well-Days of Future Life from Age 50
HEF For Men For Women
80 -8.1 -8.6
90 -3.9 -4.1
100 Base or 0 Base or 0
110 +4.0 +3.7
120 +7.0 +6.3
130 +10.5 +9.7
These forecasts show that Cardiofitness thus may have a very important effect on our duration of life. Moving from a sub-sedentary or very poor level of 80 HEF to a very good level of 130 may add 18 years to an average US person's most probable length of life. The above very low level of 80 HEF can result for a person that spends most of life sitting in cars, office and home and does no exercise. But a low level also can in part be due to unfortunate genetics. These estimates assume that cardiofitness is the only health factor changed. The proportional contribution of cardiofitness to Well-Days would be substantially less if other health factors are simultaneously improved because the health values of factors cannot be added.
Cardiofitness is potentially more important than any other major coronary disease risk factor. Some comparative risks of death are
Cardiofitness Serum Cholesterol Blood Pressure Smoking
HEF Risk Total Risk Sys/Dia Risk Cig/Day Risk
130 0.19 180 0.58 125/75 0.76 0 1.00
120 0.33 190 0.67 135/85 1.00 5 1.42
110 0.57 200 0.78 160/100 1.62 15 1.74
100 1.00 220 1.00 170/110 2.00 30 1.98
90 1.74 250 1.46 40+ 2.36
80 3.03 300 3.00
In addition to its larger effect on risk than is associated with these other factors, cardio-effective exercise and smoking are the only factors that also substantially reduce the risk of cancer. And Cardiofitness retains its health benefits as we become older. Risks associated with both cholesterol and smoking decline at older ages.
The Mechanisms by which Exercise and Cardiofitness protects: Improvements in Cardiofitness from exercise usually reduce total cholesterol levels and increase desirable HDL cholesterol levels. Cardiovascular exercise has consistently been shown to reduce blood pressures. It has been widely speculated that these effects 'explain' the effect of exercise on heart disease. This is not true. Effects of these well known factors are incorporated into the Life Ahead program based mostly on studies of research in which fitness levels were actually measured. These effects also are included in developing the genetic factors for cholesterol and are:
At a 220 level of total serum cholesterol, each increase of 1 in HEF decreases total cholesterol by about 0.2%. Thus an increase of 20 in HEF from exercise reduces total cholesterol by 4 mg/dl. This is a small effect that should reduce risk factor by 4%
Based on 6 studies, each increase of 1 in HEF improves HDL by 0.1 mg/dl. This again is a small effect. Exercise that will increase HEF by 20 units should increase HDL by 2 mg/dl. This in turn should reduce coronary and cardiovascular risk by just 6%
Based on 7 studies, each increase of 1 in HEF reduces systolic/diastolic blood pressure by 0.24/0.14 mm. Thus a improvement of 20 in HEF reduces blood pressure an average of about 5/3 mm. This should reduce average person's cardiovascular risk by about 10%.
A total of these known results for improved exercise is 20%, or a risk factor of about 0.80. The actual risk reduction for exercise that improves HEF by 20 is 0.33. This leaves the 70% majority of the risk reduction of Cardiofitness producing exercise as unexplained.
A most probable casual effect of the major benefit of Cardiofitness on coronary heart disease is that the pulsing of increased flow of blood at the elevated heart rates produced by more intensive exercise pushes coronary arteries more open. The remarkable pictures shown here are photos of the cross sections of the coronary arteries of monkeys that in example at left were fed a high cholesterol diet and not exercised, and at right with similar diet that were exercised on a treadmill for one hour three times each week. (Kramsch, N Eng J Med 305:1483) The cross section of the artery of the non-exercising monkey was 50% blocked; the artery at right had far more open cross-sectional area for flow of blood that could prevent a blockage. Arteries of men who exercised more and obtained a probable 10% increase in HEF were found by a study of Mitrani to be 15% more open. African Masai studied that had HEF measured values at 150% of sedentary had 50% larger coronary arteries, and a marathoner Clarence DeMar had arteries 3 times usual size.(Mann, Lancet 2:1308). An engineering analysis shows that risk of a blockage would be reduced at least tenfold for a coronary artery enlargement of this magnitude, and this is the only known mechanism that can now explain the very large reductions in risk that accompany improvements in Cardiofitness. Because this mechanism involves body muscle tissue it further explains how coronary risk from a change in Cardiofitness can increase after a few months of cardiovascular effective exercise and decline similarly after exercise is stopped. This was directly confirmed by the Cooper Institute research study.
Blood flow from fairly intensive exercise probable increases blood flow throughout the entire body. Thus combined with cholesterol and a larger effect of reduced blood pressure on stroke than for coronary disease this mechanism may account for the reduced risk of stroke that accompanies Cardiofitness. But as discussed in the section in Cardiofitness and cancer an entirely different mechanism almost certainly is involved in the slowing of cancer by improved Cardiofitness.
Do we Need More Research? Researchers always want more and more research. The role now defined for Cardiofitness in reducing risk of cardiovascular diseases was clearly shown and published in 1982. 41 studies even then provided a dramatic picture of validity and benefit. Today we have more than adequate further confirmation that very large reduction in rates of coronary disease are directly associated with measured differences in cardiofitness. Differences in cardiofitness - either actual or estimated - explain the differences in risk obtained in essentially all research studies on coronary disease published during five decades of the 20th century. The casual mechanisms by this happens are explained. And finally, we have the impressive research showing the the kind of exercise that produces cardiofitness protects similarly against most or all causes of cancer. Any health-interested person thus should be seriously interested in learning what Cardiofitness level now is, and what he or she can do about this to protect their future life.
The Life Ahead Valuation of Cardiofitness: Life Ahead now computes a maximum benefit from Cardiofitness from an assumed maximum difference of 30 in HEF. This is consistent with a policy of not accepting results of risk differences not well established from actual research. Thus if a present HEF is a low 80, a benefit will be computed by Life Ahead only to an HEF of 110. This improvement still will credit a five-fold reduction in risk of cardiovascular disease, and further increases in fitness probably still will contribute further. But if exercise fails to improve HEF adequately, other risk factors need to be reduced more. The program now accepts a minimum HEF of 80 and a maximum HEF of 150 in addition to the restriction of a 30 HEF difference from exercise. Benefits thus may now be computed quite conservatively for those having very good levels of Cardiofitness.
An improvement in HEF from 100 to 110 can be obtained by a moderate but brisk (it must be brisk!) walking program. An improvement of 20 HEF will require a substantial very brisk or fast walking program, or a moderate jogging or equivalent program. An improvement of 30 in HEF usually will require a program of heart rate monitored effective aerobic exercise.
But keep in mind a key problem: Individuals must maintain Cardiofitness during every year of future life to obtain its most attractive potential benefits.
A Very Major Need: Today millions are exercising faithfully and regularly. But they have no useful way of knowing what their exercise accomplishes. It seems likely that much of the exercise done by our population today - as insufficiently brisk and steady walking and inadequately cardio-intensive weight training - contributes only minimally to improving the cardiofitness that protects against heat disease, cancer, and premature death. There is no available measurement of Cardiofitness such as the HEF that is both widely known and available that confirms a value of the exercise that relates to health. Individuals need a easily understandable measurement of their Cardiofitness now, and a target value of what they need to achieve. As a very major health risk factor, a Cardiofitness value eventually should be measured as part of doctors' physical examinations and health risk valuation.
Life Ahead provides this needed measurement of Cardiofitness via the HEF. Life Ahead provides extensive analysis of what the HEF means. And it provides simple ways for measuring it on a treadmill that should become broadly available. There is a need for further testing of the HEF on real populations, and moving this or an and equivalent method into widespread use soon. In the meantime, health-interested persons can start measuring the cardiofitness level and their related health risk now.