Definition of a Risk Factor A risk factor is any attribute, characteristic, or exposure that increases the likelihood of developing a disease or healt

Risk Factor

An attribute, characteristic, or exposure that increases the likelihood of developing a disease or health condition.

Crude Rate

The total number of cases (or deaths) in a population without adjustments for other factors.

Standardized Rate

A rate adjusted for factors like age to allow fair comparisons between populations with different demographic structures.

Specific Rate

The rate for a particular subgroup, such as age-specific mortality rates.

Prevalence

The proportion of a population that has a disease at a specific time, including both new and existing cases.

Incidence

The number of new cases that develop in a given time period.

Cross-sectional Study

Observes a population at one point in time; pros include being quick and inexpensive, but it cannot determine causality.

Cohort Study

Follows a group over time to identify risk factors; it's costly and time-consuming.

Case-Control Study

Compares people with a disease to those without; it is efficient for rare diseases but subject to recall bias.

Randomized Controlled Trial (RCT)

Participants are randomly assigned to groups; it is best for causation but costly and raises ethical concerns.

Relative Risk (RR)

The ratio of disease risk in an exposed group to a non-exposed group.

Odds Ratio (OR)

The odds of disease in exposed versus non-exposed groups, commonly used in case-control studies.

Confounder

A variable that influences both the independent and dependent variables, leading to a false association.

Interaction Effect

When the effect of one variable on an outcome depends on the level of another variable.

MET (Metabolic Equivalent of Task)

A unit of measure for energy expenditure; 1 MET equals energy used at rest.

Accelerometers

Devices that measure movement intensity.

Indirect Calorimetry

Estimates energy expenditure by measuring oxygen consumption and carbon dioxide production.

Direct Calorimetry

Measures heat production in a metabolic chamber.

Doubly Labeled Water

The gold standard for measuring energy expenditure over time using isotopes.

Sedentary Behavior

Any activity with an energy expenditure of ≤1.5 METs while sitting or reclining.

Ejection Fraction

The percentage of blood ejected from the left ventricle during each heartbeat.

Respiratory Exchange Ratio (RER)

Ratio of CO₂ produced to O₂ consumed, indicating substrate oxidation.

Runner’s Health Study Findings

Running is linked to lower mortality, reduced cardiovascular disease, and improved lifespan.

Dose-Response Relationship

The correlation between the amount of physical activity and lower mortality rates.

Fat vs. Fit Controversy

Fitness matters more than body weight in predicting mortality risk.

Iowa Women’s Health Study Findings

Physical activity reduces mortality risk, even in older women.

Hours of Exercise per Week to Reduce Mortality Risk

150–300 minutes per week of moderate-intensity activity (or 75–150 minutes vigorous-intensity).

Cleveland Clinic Cohort Study Findings

Higher cardiorespiratory fitness is associated with lower mortality risk across all ages.