Higher proportion vigorous physical activity associated with lower mortality

Introduction and methods

The 2018 Physical Activity Guidelines for Americans recommend at least 150 to 300 minutes per week of moderate intensity physical activity (MPA), 75 to 150 minutes per week of vigorous intensity physical activity (VPA) or an equivalent combination of MPA and VPA (MVPA) [1]. The recommendation in the guidelines are based on the assumption that for some health outcomes VPA is associated with greater benefits than MPA [1,2]. But it remains unclear whether for the same amount of total MVPA, VPA is associated with greater benefits compared with MPA.

This study investigated whether VPA is associated with greater mortality risk reduction compared with MPA, for the same amount of total physical activity (defined as total MVPA). More specifically, the association of the proportion of VPA to total MVPA with all-cause mortality, CVD mortality and cancer mortality were examined.

Data of the National Health Interview Survey (NHIS), an annual national cross-sectional survey of civilian participants from the US, from 17 cross-sectional waves conducted from 1997 to 2013 were used. Follow-up was to December 31, 2015. After exclusion of those with missing data on physical activity, those with disabilities or unable to perform moderate of vigorous physical activity, or with diagnosis of heart disease, stroke or cancer at baseline, a total of 403,681 participants were included. Median follow up was 10.1 years (IQR 5.4-14.6).

Physical activity was measured with 2 sets of questions on frequency and duration for light intensity physical activity or MPA; and VPA. Total physical activity (defined as total MVPA in minutes per week) was calculated as MPA (min per week) + [2 x VPA (min per week)]. Proportion of VPA to total physical activity was calculated as follows: VPA x 2/MPVA x 100%.

Main results

• Participants with more than 50%-75% of VPA to total physical activity had a 17% lower all-cause mortality compared to those with 0% VPA (HR 0.83, 95%CI: 0.78-0.91), independent of total MVPA. The HR for participants with >75% to 99% VPA was 0.85 (95%CI: 0.79-0.91) compared with 0% VPA.
• Higher proportions VPA to total physical activity were not associated with CVD mortality and cancer mortality.
• Mutually adjusted models considering the guidelines recommendations of MPA and VPA showed similar associations for all-cause mortality (MPA: HR 0.83, 95%CI: 0.80-0.87 and VPA: HR 0.79, 95%CI: 0.70-0.91). VPA showed a stronger inverse association with cancer mortality compared with MPA (VPA: HR 0.89, 95%CI: 0.80-0.99 and MPA HR 0.94, 95%CI: 0.86-1.02).
• Exploratory joint associations of MPA and VPA suggested the lowest all-cause mortality risk among participants performing 150-299 min per week of MPA and 150 min per week or more of VPA (HR 0.64, 95%CI: 0.58-0.71). For CVD mortality optimum MPA and VPA combination was 1 to 149 min per week of MPA and 150 min per week or in of VPA (HF 0.56, 95%CI: 0.45-0.69). For cancer mortality, optimum was 300 min per week or more of MPA and 1 to 74 min per week of VPA (HR 0.67, 95%CI: 0.52 to 0.86).

Conclusion

References

Find this article online at JAMA Intern Med