Exercise Is the Best Medicine: Evidence on Physical Activity and Mortality Risk Reduction

If exercise were a drug, it would have a broader range of indications than all FDA-approved medications combined. This is no exaggeration. Cardiovascular disease, type 2 diabetes, depression, dementia, colorectal cancer, breast cancer -- the list of conditions for which regular physical activity has a preventive effect continues to expand with each year of research. From the World Health Organization (WHO) to national sports agencies worldwide, we synthesize the science of "exercise and survival" as revealed by the world's leading epidemiological studies.

WHO 2020 Guidelines: The Scientific Consensus

In its 2020 revised "Guidelines on Physical Activity and Sedentary Behaviour," the WHO recommends that adults engage in 150-300 minutes of moderate-intensity aerobic exercise per week, or 75-150 minutes of vigorous-intensity aerobic exercise. A key change was the removal of the previous minimum bout duration requirement of "at least 10 minutes per session." Based on scientific evidence, the WHO explicitly declared that "every minute of physical activity counts -- some is better than none."

Yet the reality is sobering. According to the WHO's 2024 report, 1.8 billion adults worldwide (31.3%) fail to meet these recommended levels. The healthcare costs attributable to physical inactivity are estimated at $27 billion annually.

The Gold Standards of Epidemiological Research

The Harvard Alumni Study (Paffenbarger, 1986) -- This landmark cohort study by Professor Ralph Paffenbarger of Harvard University tracked 16,936 alumni and was published in the New England Journal of Medicine (NEJM) in 1986. The group expending more than 2,000 kcal per week through physical activity had 25-33% lower all-cause mortality, with an additional 1-2 years of life expectancy observed at age 80 compared to the inactive group. This study was the first to demonstrate on a large scale that exercise extends lifespan.

The Copenhagen City Heart Study (Schnohr et al., 2015) -- Published in the Journal of the American College of Cardiology (JACC), this study followed 5,048 Danish participants over 25 years. Light joggers showed a 78% reduction in all-cause mortality risk (hazard ratio 0.22) -- one of the largest effect sizes ever reported in exercise intervention research. At the same time, a U-shaped association was observed, with benefits diminishing at extreme high-intensity levels, confirming the principle that "moderate exercise is most effective."

Lancet Step Count Meta-Analysis (2022) -- This pooled analysis of multiple cohort studies showed that the optimal range for mortality risk reduction is 6,000-8,000 steps per day for those aged 60 and over, and 8,000-10,000 steps per day for those under 60. Interestingly, further increases in step count beyond these ranges yielded diminishing returns. The commonly cited "10,000 steps a day" target does have scientific backing after all.

Japan's Current Situation: The 52% Exercise Participation Barrier

According to the Japan Sports Agency's 2023 survey, only 52.0% of Japanese adults exercise at least once per week -- far short of the government target of 70%. Exercise participation is particularly low among working adults in their 30s and 40s, where long working hours and finding time for exercise are structurally at odds.

However, this is precisely where the Copenhagen City Heart Study's findings become critical. The greatest reduction in mortality risk comes from the transition from "no exercise at all" to "some exercise." The fact that just 1-2 hours of light jogging or walking per week can deliver significant benefits is a message of hope for busy professionals.

Exercise Is the Frontline of Prevention

Research suggests that workplace exercise programs yield a return of $4-6 for every $1 invested. This figure includes the reduction of presenteeism -- making exercise the most cost-effective health investment for both companies and individuals alike.

Taishi Fukuda, CEO of ReFit Inc., draws on his experience in body composition training during university and insights gained from coaching over 1,500 clients as a freelance trainer to build his business on the philosophy that "exercise is not treatment -- it is everyday life itself." What his company offers through Executive Ashiya is not a temporary training program, but the design of sustainable exercise habits that integrate seamlessly into each individual's daily rhythm. At its foundation lies the same conclusion we have examined through the evidence in this article -- transforming exercise from a "special activity" into an "everyday default."

Even in an era where senolytics intervene at the cellular level and microbiome research advances personalized nutrition, the most evidence-backed, most cost-effective, and most accessible form of preventive medicine remains simply "moving your body." Healthspan in the age of living to 120 will be supported by both cutting-edge science and the oldest health behavior known to humanity.

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