Minimal and optimal daily step counts for healthy individuals to reduce mortality and CVD risks
Relationship of Daily Step Counts to All-Cause Mortality and Cardiovascular EventsLiterature - Stens NA, Bakker EA, Mañas A, et al. - J Am Coll Cardiol. 2023 Aug 26;S0735-1097(23)06400-8. doi: 10.1016/j.jacc.2023.07.029
Introduction and methods
Studies have shown that walking an additional 1000 steps per day is associated with a reduced risk of all-cause mortality of 12%–15% [1,2] and lower odds of frailty . However, the minimal and optimal daily step counts for health improvements have not been fully established.
Aim of the study
The authors examined the dose-response association of objectively measured step count metrics with all-cause mortality and incident CVD in the general population, as well as the moderating effects of sex, device type and wear location, and step cadence on the step count assessment.
In this systematic review and meta-analysis, a systematic literature search was performed in PubMed and EMBASE from inception to October 2022 to identify eligible prospective cohort studies. In total, 12 studies were included (n=111,309). The risk of bias was low for all studies, except for one that had an intermediate risk for bias. Publication bias was considered to be minimal.
The primary endpoints were all-cause mortality and incident fatal or nonfatal CVD, which included ischemic or coronary heart disease, stroke, and/or HF.
Categorical dose-response association between daily step count and clinical outcomes
- During a median follow-up period of 77.8 months (IQR: 71.6–82.9), intermediate step counts (median: 6000 steps/day; IQR: 5392–6775) were associated with a lower risk of all-cause mortality (adjusted HR (aHR): 0.64; 95%CI: 0.56–0.72; I²=53%; 95%CI: 7%–76%) compared with low step counts (median: 3166 steps/day; IQR: 2375–4191).
- The risk reduction for the association of daily step count with all-cause mortality was even larger for individuals with high step counts (median: 10,000 steps/day; IQR: 8843–11,082) compared with those with low step counts (aHR: 0.50; 95%CI: 0.42–0.60; I²=62%; 95%CI: 26%–80%).
- During a median follow-up time of 72.9 months (IQR: 66.4–80.4), intermediate step counts (median: 5737 steps/day; IQR: 5449–6000) were associated with a lower risk of CVD (aHR: 0.58; 95%CI: 0.46–0.73; I²=56%; 95%CI: 0%–85%) compared with low step counts (median: 2022 steps/day; IQR: 1468–2885), as were high step counts (median: 11,000 steps/day; IQR: 9923–12,024; aHR: 0.42; 95%CI: 0.33–0.53; I²=20%; 95%CI: 0%–88%).
Continuous dose-response association between daily step count and clinical outcomes
- Continuous dose-response analyses showed nonlinear trends for the associations of daily step count with all-cause mortality and incident CVD (both P for nonlinearity<0.001).
- The risk reduction became statistically significant for the association with mortality at 2517 steps/day (aHR: 0.92; 95%CI: 0.84–0.99) and for CVD at 2735 steps/day (aHR: 0.89; 95%CI: 0.79–0.99), compared with the reference level of 2000 steps/day.
- Further increases in step count were associated with a decreased mortality risk up to 8763 steps/day (aHR: 0.40; 95%CI: 0.38–0.43) and a decreased CVD risk up to 7126 steps/day (aHR: 0.49; 95%CI: 0.45–0.55).
- Additional reductions in the risks of mortality and CVD were not statistically significant (aHRs for 16,000 vs. 2000 steps/day: 0.35; 95%CI: 0.30–0.40 and 0.42; 95%CI: 0.33–0.53, respectively).
- Changes in risk estimates following increases or decreases of 1000 steps/day were strongly dependent on baseline step count.
Moderating effects on step count assessment
- There were no important differences in risk reductions between men and women.
- More pronounced reductions in the all-cause mortality risk were observed in studies in which hip-worn accelerometers were used (8 studies) compared with studies investigating wrist-worn accelerometers (1 study) or pedometers (3 studies).
- After adjustment for total step count, intermediate step cadence (median: 66 steps/min; IQR: 63–67) was associated with a lower mortality risk (aHR: 0.78; 95%CI: 0.65–0.93; I²=51%; 95%CI: 0%–84%) compared with a low step cadence (median: 25 steps/min; IQR: 25–25), as was high step cadence (median: 90 steps/min; IQR: 89–90; aHR: 0.79; 95%CI: 0.67–0.94; I²=13%; 95%CI: 0%–87%).
In this systematic review and meta-analysis of prospective cohort studies among the general population, walking a minimum of ~2600 steps per day lowered the risk of all-cause mortality by 8% compared with a daily step count of 2000, while a daily minimum of ~2800 steps reduced incident CVD risk by 11%. The optimal daily step count for risk reduction was ~8800 for mortality (leading to 60% risk reduction) and ~7200 for CVD (leading to 51% risk reduction). Intermediate and high step cadences were also associated with a decreased mortality risk compared with a low step cadence, irrespective of total step count.
The authors believe that setting physical activity goals based on step count could be a promising public health tool and contend that “[ph]ysicians may stimulate individuals, even those who are moderately active, to increase their physical activity with at least 1,000 steps/day.”