The introduction of cheap accelerometers via the mobile phone industry had the side-effect of allowing the research community to accurately assess the effects of varying low levels of physical activity on long-term health. Self-reporting is particularly inaccurate in this range of exertion, and thus the use of accelerometers in studies enabled a much more accurate determination of the lower end of the dose-response curve for exercise. The results demonstrated that even small amounts of exercise are very much better than no exercise. Double the small amount of exercise is better yet. The paper here is an example of this sort of dose-response gradient at lower levels of exercise, focused on fast walking in older people.
While the health benefits of daily walking are well-established, limited research has investigated effects of factors such as walking pace on mortality. Data from the Southern Community Cohort Study were used, including information from nearly 85,000 predominantly low-income and Black individuals recruited during 2002-2009 across 12 southeastern US states. Participants provided baseline information on daily walking pace and time, demographic information, lifestyle factors, and health status. Mortality data were collected until December 31, 2022.
Over a median follow-up of 16.7 years, 26,862 deaths occurred. Significant associations were found between all-cause mortality and daily fast walking time. Fast walking as little as 15 minutes a day was associated a nearly 20% reduction in total mortality (hazard ratio, HR: 0.81), while only a 4% reduction in mortality (HR: 0.96) was found in association with more than three hours of daily slow walking. Fast walking was independently associated with reduced mortality, regardless of the leisure-time physical activity levels. The inverse association was more pronounced for mortality due to cardiovascular diseases than cancers. Participants with baseline comorbidities had larger risk reductions compared to their generally healthy counterparts, although all individuals benefited from fast walking.
