Final answer:
The foundational case-control study by Doll and Hill in 1950 on smoking and lung cancer laid the groundwork for linking lifestyle factors with disease risk, while subsequent research has demonstrated that increased physical activity significantly lowers the risk of various diseases and increases life expectancy.
Step-by-step explanation:
Classic Study in Physical Activity and Disease Risk
The classic case study that pioneered the idea that larger doses of physical activity lower the risk of disease is not about physical activity per se, but rather it is the research on smoking and lung cancer by Doll and Hill. This research laid the foundation for subsequent studies into lifestyle factors and disease risk. Doll and Hill's cohort study in 1951 followed almost 50,000 British male physicians over 50 years, which conclusively linked smoking with lung cancer. Their initial case-control study in 1950 was pivotal in identifying smoking as a major risk factor for lung cancer.
Building on the methodological foundations laid by studies such as Doll and Hill's, current public health guidelines underscore the importance of physical activity for reducing the risk of various diseases. According to the 2018 Physical Activity Guidelines for Americans issued by the Department of Health and Human Services (HHS), adults should engage in regular aerobic physical activity for at least 150 to 300 minutes per week at moderate intensity. Increased physical activity has been associated with numerous health benefits, such as reducing the risk of heart disease, stroke, high blood pressure, Type 2 diabetes, and some types of cancer, as well as improving overall health markers like cardiovascular and muscular fitness, bone density, cognitive function, and helping with weight loss and maintenance.
Moreover, regular physical activity has been linked to increased life expectancy, with those adhering to the HHS recommendations gaining upwards of 4 years of life. This protective effect against mortality underlines the critical role of physical exercise in promoting longevity and staving off chronic diseases.