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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 CFR 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.  Thus it is of interest to determine if the risk values for the individual diseases are consistent with the value independently determined for risk for all causes of death. 

Multiplying the risk ratios for cardiovascular disease and cancer times their actual overall risks from age 50 through age 70 develops an expected risk ratio on death from all causes of 3.63% per CFR.  This is in close agreement with the 3.52% per CFR found from the actual research of death from all causes vs. the CFR.   This verifies that primary risks related to Cardiofitness are for cardiovascular diseases and cancer, and that the combined effect of Cardiofitness on these diseases explains the result for measured values of Cardiofitness on overall death.  This consistency provides  further confidence that the valuations for both individual diseases and for overall death rates vs. Cardiofitness are correct.

Low Cardiofitness can be a Major Risk:   Most research on fitness 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 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 CFR by definition.  Cardiofitness of groups of individuals moves downward from this value of 100 to 80 CFR for a person doing both no exercise and a minimum of physical activity, and to 70 CFR 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 CFR for  major death from disease and death:

CFR Level  Cardiovascular Disease  Cancer  Death,all Causes

% per CFR         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 CFR 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 CFR of 130, CFR 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 CFR from exercise, the actual research studies included individuals that had CFR 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 CFR.

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 CFR 10 or more units lower or higher than average from genetics.  Thus a person that is exercising faithfully still may have an CFR below 100.  Thus there is no substitute for knowing our CFR 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.  Liife 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 CFR determined with good accuracy, it becomes quite straightforward to compute how CFR 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 CFR 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

 CFR              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 CFR 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 CFR 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.

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

  CFR         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 CFR decreases total cholesterol by about 0.2%.  Thus an increase of 20 in CFR 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 CFR improves HDL by 0.1 mg/dl.  This again is a small effect.  Exercise that will increase CFR by 20 units should increase HDL by 2 mg/dl.  This in turn should reduce coronary and cardiovascular risk by 6%

Based on 7 studies, each increase of 1 in CFR reduces systolic/diastolic blood pressure by 0.24/0.14 mm.  Thus a improvement of 20 in CFR 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 CFR 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 CFR were found by a study of Mitrani to be 15% more open.  African Masai studied that had CFR 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 decline rather rapidly in response to exercise, and increase similarly after exercise is stopped.

Blood flow from fairly intensive exercise probable increases blood flow throughout the entire body.  Thus combined with the 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 nearly 200 different comparisons of the health risks of cardiofit and less fit individuals that show essentially the same thing found more than two decades back.  Today's research confirms this not only far more extensively but now shows that Cardiofitness  also protects against cancer.  How long do we need to wait?   Any health-interested person should be seriously interested in learning what their Cardiofitness level now is, and what they 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 CFR.  This is consistent with a policy of not accepting results of risk differences not well established from actual research.  Thus if a present CFR is a low 80, a benefit will be computed by Life Ahead only to an CFR 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 CFR adequately, other risk factors need to be reduced more. The program now accepts a minimum CFR of 80 and a maximum CFR of 150 in addition to the restriction of a 30 CFR difference from exercise.  Benefits thus may now be computed quite conservatively for those having very good levels of Cardiofitness.

An improvement in CFR from 100 to 110 can be obtained by a moderate but brisk (it must be brisk!) walking program. An improvement of 20 CFR will require a substantial very brisk or fast walking program, or a moderate jogging or equivalent program.  An improvement of 30 in CFR usually will require a program of effective aerobic exercise. 

But keep in mind a key problem:  Individuals must maintain Cardiofitness during every year of future life to obtain its 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. There is no available measurement of Cardiofitness such as the CFR that is both widely known and available 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.

Life Ahead provides this measurement of Cardiofitness via the CFR.  It provides extensive analysis of what the CFR means.  And it provides simple ways for measuring it on a treadmill that should become broadly available and that some people can use to value themselves. There is a major need for moving this or similar method into widespread use.