In what might be the best return on investment since Bitcoin’s early days, scientists have discovered that every hour of walking could yield up to six hours of additional life. Unlike cryptocurrency, however, this investment is guaranteed by the laws of human biology. An exciting modeling study reveals that if every American over the age of 40 was as physically active as the most active quarter of the population, they could expect to live an extra five years on average.
While scientists have long known that physical inactivity increases the risk of diseases like heart disease and stroke, this study is the first to quantify exactly how many years of life Americans might be losing due to insufficient physical activity. The findings suggest that the impact of physical inactivity on life expectancy may be substantially larger than previously estimated.
The study, led by researchers from Griffith University in Australia and various institutions worldwide, challenges previous estimates of physical activity’s benefits, which were largely based on self-reported data. By using more accurate device-based measurements, the researchers found that the relationship between physical activity and mortality is about twice as strong as earlier studies suggested.
Consider this: The most active 25% of Americans over age 40 engage in physical activity equivalent to about 160 minutes of normal-paced walking (at 3 miles per hour) every day. If all Americans over 40 matched this level of activity, it would boost the national life expectancy at birth from 78.6 years to nearly 84 years.
For the least active quarter of the population to match the most active group, they would need to add about 111 minutes of daily walking (or equivalent activity) to their routine. While this might sound challenging, the potential reward is significant: nearly 11 additional years of life expectancy.
To put this in perspective, that’s roughly equivalent to eliminating half the life expectancy gap between the U.S. and countries with the highest life expectancy globally.
Not All Talk: How Scientists Walked The Walk
Study authors analyzed data from the National Health and Nutritional Examination Survey (NHANES), focusing on Americans aged 40 and older who wore activity monitors for at least four days. Unlike previous studies that relied on participants’ memory and honesty about their activity levels, these monitors provided objective measurements of every movement throughout the day.
The results showed a striking “diminishing returns” effect in the relationship between physical activity and longevity. The greatest benefits were seen among the least active individuals: moving from the lowest activity quarter to the second-lowest required just 28.5 minutes of additional walking per day but could add 6.3 years to life expectancy. That means every hour of walking for this group translated to an extra 6.3 hours of life — an impressive return on investment.
As people became more active, the additional benefits per hour of activity decreased but remained significant. For those in the second-lowest activity quarter, reaching the activity level of the most active group would require about 83 additional minutes of walking per day and could add 4.6 years to their life expectancy.
Never Too Late
These findings, published in the British Journal of Sports Medicine, have important implications for public health policy and urban planning. Creating walkable neighborhoods, maintaining safe parks and green spaces, and designing cities that encourage active transportation could help populations achieve these higher activity levels naturally. The researchers emphasize that increasing physical activity at the population level requires a comprehensive approach that considers social determinants and addresses inequalities in access to activity-promoting environments.
The study also highlighted significant disparities in physical activity levels across socioeconomic groups. In 2020, only 16.2% of men and 9.9% of women in the lowest income group met the guidelines for aerobic and muscle-strengthening activities, compared to 32.4% and 25.9% in the highest-income group, respectively. This suggests that initiatives to promote physical activity could help reduce health inequalities.