▎ WuXi AppTec content team editor
With the popularity of pedometers in smartphones and wearables, how many steps we take per day is an easy way for us to understand how much we are active. Walking 10,000 steps a day has invisibly become a small goal of daily health for many people.
However, whether the "10,000" steps per day are scientific and what the optimal number of healthy steps per day is, has always been controversial. Different individual studies have different conclusions. There is also a lack of evidence-based public health guideline recommendations for how many steps to take each day to reap health benefits.
Recently, the authoritative medical journal The Lancet Public Health published a large-scale study that answered this more comprehensively based on existing evidence-based evidence. The research team conducted a meta-analysis of 15 studies from four continents covering nearly 50,000 participants.
It was found that the threshold for obtaining health benefits was not high, and as long as you walked more, it was closely related to longevity. In addition, for adults aged < 60 years and ≥ 60 years of age, the longevity benefit may not increase significantly after more than 8000-10000 steps per day and 6000-8000 steps per day, respectively.
Screenshot source: The Lancet Public Health
The analysis came from the Steps for Health Collaborative, an international organization that has been concerned about the association between steps and walking speed and health outcomes, including mortality. In this analysis, a total of 15 studies from Asia, Australia, Europe and North America completed between 1999 and 2018 were included. These studies all complete standardized statistical analyses created by the cooperative organization.
The total sample size of all studies was 47471 adults, the median follow-up period was 7.1 years (the total follow-up time cumulative was 297837 person-years), and a total of 3013 deaths during the follow-up period.
Overall, the median number of steps per day in the study population was 6495 steps, < 60-year-old adults had significantly higher steps than ≥ 60-year-old adults (7803 vs 5649 steps, p=0.033). Based on the average number of steps per day, from few to many steps per day, participants were divided into four groups (25% per group), and the median values of the daily steps in each group were: 3533 steps, 5801 steps, 7842 steps and 10901 steps.
After adjusting for other potential influencing factors, the risk of death was reduced by 40% and 45%, respectively, compared with the group that walked the least (3533 steps) per day: the risk of death in groups 2 (5801 steps) and 3 (7842 steps), respectively, and the group that walked the most per day (10901 steps) had a 53% lower risk of death.
The research team notes that this risk reduction is similar to the benefits of moderate- to high-intensity exercise observed in other studies.
Further analysis revealed that the more steps per day, the lower the risk of death. Moreover, ≥ 60-year-olds walk more before 6,000 steps, < 60-year-old adults before 8,000 steps, more walking is associated with plummeting risk of death, which means that people who walk less every day can especially benefit from it.
Dose-response relationship between daily steps and all-cause mortality. (Image source: References[1])
But there is also an upper limit to this benefit, and the risk of death gradually stabilizes: for ≥ 60-year-old adults, the benefit of preventing death does not increase after more than 6000-8000 steps per day; for < 60-year-old adults, the "upper limit" of the benefit is 8000-10000 steps. For different genders, this "upper limit" is not significantly different.
For this age difference, the research team discussed that as we age, limited mobility, decreased aerobic capacity, and decreased biological efficiency may limit the number of steps per day in older adults, and with the same relative physiological stimulus, older people have absolute fewer steps, so older people achieve similar relative health improvements and require fewer steps.
Notably, despite the "upper limit" of benefits, the team did not observe that more steps were associated with an increased risk of death.
Image credit: 123RF
In addition, after considering the total number of steps per day, the association between walking speed and risk of death was not significant, with only two indicators being exceptions: the 25% of people with the fastest peak walking speed of 30 minutes or 60 minutes had a 33% lower risk of death than the slowest 25%. The median peaks of 30-minute walking and 60-minute walking speed were 64.1 steps/min and 57.5 steps/minute among all study populations. The research team notes that peak walking speed may be a better reflection of fitness levels compared to average pace.
This means that, overall, no matter what speed you walk, walking more is beneficial for longevity until there is no significant additional benefit after reaching 8000-10000 steps (depending on age).
The study's strengths include broad geographic coverage, recording steps by device rather than self-reporting, consistent approach to each study, and inclusion of unpublished studies to reduce bias (positive findings tend to be published earlier and more frequently). Of course, the study also has limitations, such as the type of pedometer device in different studies, the wearing position is different, and the pedometer may not be able to fully capture the short distance, short-term walking or slow activities of the elderly that are common in daily life.
The Lancet-Public Health commentary notes that the study adds important evidence that steps per day are strongly associated with the risk of death, regardless of age or gender. This result may provide researchers, clinicians, and public health personnel with alternative targets to increase physical activity and thus improve individual and population health.
Currently, WHO guidelines recommend:
Adults aged 18-64 years, including all physical activity, are recommended to engage in 150-300 minutes of moderate-intensity activity per week, or at least 75-100 minutes of high-intensity activity, or an equivalent combination of moderate-intensity activity and high-intensity activity. In addition, moderate or higher intensity muscle strengthening (including weight training, core exercises) is done at least 2 days a week.
Children and adolescents (5-17 years old), an average of 60 minutes of moderate-intensity to high-intensity activity per day can bring many benefits, and the more activity the better.
Older adults (over 65 years old) should do moderate- or higher-intensity exercises at least 3 days a week, with a focus on functional balance and strength training to enhance body function and prevent falls.