The mortality benefit achieved through doing more daily steps increases but only up to a certain point and then plateaus
A mortality benefit accrues from taking more daily steps but this benefit plateaus and depends upon an individual’s age. This was the main finding of a meta-analysis by a team from the Department of Kinesiology and Institute for Applied Life Sciences, University of Massachusetts Amherst, Massachusetts, US.
Measuring the number of steps taken each day has become much easier over the last few years largely because of an increase in the availability of fitness trackers. Moreover, though the idea that the target for beneficial health is at least 10,000 steps/day, there is a lack of evidence to justify this figure.
Indeed, it is possible that the actual number of steps/day required could be actually much lower, with one study in older women finding that the mortality rates progressively decreased before levelling at approximately 7500 steps/day.
In addition, the optimal number of steps needed to achieve a mortality benefit is likely to be influenced by other factors such as age and gender, as well as the pace of walking, although observational studies have found that there is no significant association between step intensity and mortality after adjusting for total steps per day.
For the present study, the US team set out to assess the mortality benefit derived from the number of steps taken per day and considered how this might be affected by both age and gender. They also sought to clarify if there was an association between the stepping rate (i.e., how fast someone walked) and all-cause mortality.
They searched for studies which examined the relationship between daily steps and mortality in adults (> 18 years of age). After identifying relevant articles, the US team asked the study investigators to provide additional data and to calculate the peak 30 and 60 minute stepping rates, as well as the time spent walking at 40 steps/min or faster and 100 steps/min.
The primary outcome was set as all-cause mortality. The total number of median daily steps was categorised into quartiles; up to 3553 (quartile 1); 5801 (quartile 2); 7842 (quartile 3) and 10,901 (quartile 4). Hazard ratios were calculated for the mortality benefits and adjusted for several factors including age, sex, education level, body mass index and other health-related variables.
Mortality benefit and daily step count
The authors identified a total of 15 eligible studies which included 47,471 individuals with a mean age of 65 years (68% female) and who were followed-up for a median of 7.1 years. The overall median number of steps was 6495 and individuals under 60 years of age had a higher median number of daily steps compared to those over 60. (7803 vs 5649, under 60 years vs over 60 years of age). In the cohort as a whole, there were 3013 deaths recorded.
Compared to the lowest quartile, the overall adjusted hazard ratio for all-cause mortality in the highest quartile was 0.47 (95% CI 0.39 – 0.57). When comparing those under versus over 60 years of age, there was a greater mortality benefit for older individuals (HR = 0.60 vs HR = 0.43, under 60 vs over 60). In addition, there was a higher benefit for women compared to men (HR = 0.43 vs HR = 0.52, female vs male).
The hazard ratios for mortality plateaued for adults 60 years and older at 6000 – 8000 steps/day and between 8,000 – 10,000 for those under 60 years of age.
The mortality benefit was also significant for a higher step rate for both 30 and 60 minutes but not significant for the time spent walking at 40 or faster, at 100 steps/minute. In other words, didn’t seem to matter if someone walked faster.
The authors concluded that while mortality benefits can be achieved at below the popular reference value of 10,000 steps/day, these benefits plateau and are not increased by taking further steps.
Citation
Paluch AE et al. Daily steps and all-cause mortality: a meta-analysis of 15 international cohorts Lancet Public Health 2022
