Chapter 4
All-Cause Mortality
“A N D I W I L L S T R I K E D O W N U P O N T H E E W I T H G R E AT V E N G E A N C E A N D F U R I O U S A N G E R
T H O S E W H O W O U L D AT T E M P T TO P O I S O N A N D D E S T R OY M Y B R OT H E R S . A N D Y O U W I L L
K N O W M Y N A M E I S T H E LO R D W H E N I L AY M Y V E N G E A N C E U P O N T H E E .”
EZEKIEL 25:17
The average life expectancy of a U.S. citizen is about 75 for a male & 80 for a female. This ranks
among the lowest among industrialized nations.
Physical inactivity is a burden to the U.S. causing an estimated 191,000 deaths a year from all
causes.
2 leading causes of death are: (1) CHD (2) stroke & other cerebrovascular diseases—these
account for 22% of all deaths worldwide and 26% of deaths in high-income countries.
Physical activity protects against premature death from all causes and against the development of
coronary heart disease and stroke.
H: Physical inactivity (or low fitness levels) increase the risk of all-cause mortality.
Women tend to live longer than men: 75 for a male & 80 for a female (in the US).
Why? Sex hormones—Testosterone is linked with hazardous behavior & undesirable cholesterol
levels, while estrogen is an antioxidant (protecting against cell damage) and appears to regulate
enzymes that favorably effect cholesterol metabolism. Long life in women may also be linked to a
genetic advantage for childbirth and care of the young.
Living longer, does not, however, mean more years of good health.
The leading causes of death (mortality) are: (1) heart disease (2) cancer (3) cerebrovascular
disease. These account for more than half of all deaths (in US). Heart disease and cancer are 1 &
2 for both men and women. Men—the 3rd cause is accidents & for women it is cerebrovascular
disease.
There is strong evidence showing that PA or fitness is inversely associated with the risk of
developing each of these diseases.
Highly active men had a 22% lower risk of all-cause mortality compared with low-active men, while highly active
women had a 31% lower risk. Moderately active men and women had a 19% and 24% lower risks, respectively.
Early studies of PA and all-cause mortality tended to focus on occupational PA, later studies—in particular, those
conducted in the 1980’s and later—increasingly focused on leisure-time PA because PA in the workplace had
declined in Western developed nations during the late 1950’s to 1960’s as industry moved from manual to
mechanized labor.
Studies (of physical activity)--P-80-84. Primarily measured using self-reports (Subjectivity).
Physical Fitness & Physical Activity: Physical fitness is a concept different form but related to physical activity.
Physical fitness represents a physical condition while physical activity represents a behavior.
While physical fitness has a genetic component, regular PA can improve cardiorespiratory fitness in most people.
Studies (of physical fitness)—P-85-87. Tends to be measured objectively (treadmill, etc.).
ALL of these studies (so far) have been observational epidemiologic studies, not establishing cause and effect.
•Sedentary behavior, or sitting, may represent an independent risk factor for heart disease separate
from PA.
•Heart disease is the leading cause of death in the USA and in most high-income countries.
•Sedentary behavior is a risk factor for all-cause mortality.
•Even among people active enough to meet PA recommendations, those spending more time sitting
were at increased risk of all-cause mortality compared with those sitting less.
•The Canada Fitness Survey showed that more sitting time is associated with higher mortality
rates, regardless of how much subjects exercised during their leisure time.
Changes in Physical Activity or Fitness and All-Cause Mortality
Changing from low to high physical activity or fitness levels is associated with lower mortality
rates compared with remaining at low levels.
Conversely, changing from high to low levels is associated with mortality rates similar to those
associated with remaining at low levels—as with the following studies.
Preceding studies were Observational Epidemiologic Studies—studies of this design cannot
prove cause and effect—but they can provide info that strengthens the premise of a causal link. P87.
Harvard Alumni Health Study.
Study of Osteoporotic Fractures.
Aerobic Center Longitudinal Study.
Norwegian Men.
Are the Associations Real?
Chance? P-89.
Bias? [reverse causation]
Misclassification?
Strength of the Evidence. P-90.
Temporal Sequence.
Strength of Association.
Consistency of results.
Biological Plausibility.
Dose Response
How Much Physical Activity is Needed to Decrease Risk of Premature Mortality?
How Much?—Can refer to: total volume of energy expended, intensity, duration, frequency. Most
studies have used volume of energy expended.
2 to 2.5 hours per week of moderate-intensity physical activity is sufficient to significantly
decrease all-cause mortality rates.
Walking 2 or more hours per week.
“Some is good; more is better.”
What about vigorous vs. lower intensity—with the same energy expenditure for each?
Weekend Warriors. (frequency).
Current guidelines recommend 150 min/week of moderate intensity aerobic activity or 75
min/week of vigorous intensity physical activity—work, leisure, sports…whatever..