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Stepping—encompassing walking, running and stair-climbing—is the fundamental mode of human movement. Higher stepping volume and intensity is associated with favourable health outcomes.1 2 Over the last quarter of the century, stepping has declined by over 1000 steps per day (7%–13% of total count,3 roughly equivalent to ~10 min of brisk walking). As a simple ‘objective’ measure of ambulatory physical activity, formal stepping-based recommendations may provide a target that is easy to understand and monitor. As self-monitoring of steps may be an effective physical activity intervention, such recommendations may support more people to be sufficiently active. This editorial discusses the opportunities and challenges surrounding the addition of stepping-based recommendations to future guidelines.
Daily steps: an old-new target?
Current physical activity recommendations are based on weekly duration (time) of moderate and vigorous activity (MVPA).4 For some people steps may be an easier to monitor and more concrete behavioural metric than time at a particular intensity. For example, step counting devices (pedometers, accelerometers or smartphones) have historically been more accessible than MVPA time-quantifying devices. Simple mechanical pedometers first appeared almost 60 years ago around the Tokyo 1964 Olympics, with the Yamasa company-designed ‘Manpo-Kei’ (‘10 000 steps metre’) being the first commercial step counter. The proliferation of step-counting devices in the last 20 years saw the 10 000 daily steps target being treated as an unofficial goal that increasingly attracted public attention (online supplemental image 1).
Supplemental material
Opportunities
As cohort studies mature, it is likely that more stepping dose–response studies will be available to inform future guidelines. Consumer trends present another public health opportunity: it has never been easier to track steps and set goals through ubiquitous technology. For example, 93%5 of people in the UK own smartphones capable of counting steps. Ownership of fitness trackers and smartwatches is also substantial (18% and 17%), although there are clear socioeconomic inequalities in ownership that may compromise population health gains through self-monitoring steps.
Challenges
Evidence synthesis
Critically, guideline developers should acknowledge that the questionnaires used to derive current time-based MVPA targets4 and step-counting devices capture different constructs: questionnaires capture continuous blocks of time when bouts of MVPA (including stepping) occur, whereas devices capture stepping of any duration and intensity. On its own, the number of steps is an intensity-agnostic metric which does not reflect short and intermittent (up to 1–2 min) vigorous intensity bouts6 which may be associated with health benefits over and above stepping volume.1 2 Some recent 24 hours accelerometry studies using wrist or thigh-worn devices1 2 7 8 suggested that optimal mortality and chronic disease risk factors reduction occur at around the popular 10 000 steps per day target. In its entirety, however, literature on minimal and optimal numbers of steps is far from conclusive as there are major differences in the calculation and reporting methods across studies1 2 7–10 (figure 1). Numerous other methodological issues merit attention during evidence syntheses in future guidlines, including (A) the lack of clarity on how validity varies across accelerometer placements (eg, wrist1 2 8 vs hip9 10 vs thigh7; (B) the differential definition of a ‘step’ across counting method (eg, how static shuffling counts)1 2 10; (C) how calculations of minimal and optimal daily steps are affected by the use of different reference groups across studies, for example, 12482 vs 15441 vs 200010 steps/day; (D) how real-time behavioural feedback affects estimates from consumer-level devices that may be worn for years8 and (E) how the output of such devices compares with research grade devices worn for a week or less.1 2 7 9 10
Indicative multivariable-adjusted dose–response associations* of daily steps and all-cause mortality from studies that used wrist-worn (A) or waist-worn (B) accelerometers. (A) From Del Pozo Cruz et al.2 UK men and women aged 40–79 (mean: 61) years at accelerometry baseline (n=78 500). Wrist accelerometry. Log-relative HRs. (B) From Lee et al.10 US women aged 62–101 (mean: 72) years at accelerometry baseline (n=16 741). Waist accelerometry. Relative HRs. *Figures reproduced under CC-BY licence, which permits others to distribute, remix, tweak and build on the work without permission, provided that credit is given to the original authors and journal.
Evidence translation
Contrary to the current time-based recommendations that are harmonised across adult population groups,4 some stepping literature indicates age differences in dose–response associations,9 making identification of a single stepping target uncertain. The likelihood that time-based and steps-based recommendations will coexist side by side creates a need for messaging consistency so that both targets represent similar amounts of physical activity. Assuming a constant cadence of 110 steps per min on level ground, a direct interpretation of the currently recommended 150–300 moderate intensity physical activity minutes per week4 would give approximately 2350–4700 MVPA steps per day. The minimum beneficial stepping doses identified in recent studies1 10 are aligned in terms of the absolute range but do not specify stepping intensity.1 2 10 Considering that even physically inactive adults record around 2000–4000 light intensity steps during essential incidental activities2 it is unclear what is the equivalence of the two sets of minimal doses. Similarly, recent literature reporting specifically optimal daily steps (point of lowest risk)1 2 7 8 includes all steps, not just those performed at moderate to vigorous intensity. With some recent evidence suggesting that metrics reflecting higher stepping intensity may be independently associated with further risk reduction,1 2 guideline developers may consider specific stepping intensity recommendations.
Conclusions
As the only health behaviour that is passively tracked by nearly ubiquitous technology (smartphones), stepping has a privileged position. Stepping dose–response research has progressed in recent years, providing new insights to inform future physical activity guidelines. The challenges outlined above are not insurmountable, previous guideline developers faced unquestionably harder obstacles while developing the current time-based MVPA recommendations using modestly valid self-reports of leisure-time physical activity. The coexistence of steps and time-based recommendations in any future guidelines requires caution to ensure that the former are complementary rather than antagonistic to the latter targets.
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Supplementary materials
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Footnotes
Twitter @M_Stamatakis, @MarieHMurphy, @timchico, @karenmilton8, @JasonGill74
Contributors All authors have contributed sufficently to warrant authorship. ES and JG conceived the idea, ES drafted the material, all coauthors reviewed the manuscript critically and redrafted parts.
Funding ES is funded by the National Health and Medical Research Council (Australia) through an Investigator Grant (APP1194510). BDPC is funded the Government of Andalusia (Spain), Research Talent Recruitment Programme (BdPC, EMERGIA 2020/00158).
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Competing interests None declared.
Provenance and peer review Commissioned; externally peer reviewed.
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