Physical Activity Volume, Intensity, and Mortality: Harmonized Meta-Analysis of Prospective Cohort Studies

Area of Science:

• Epidemiology
• Public Health
• Exercise Science

Background:

• Uncertainty exists regarding the independent association of moderate-to-vigorous physical activity (MVPA) with mortality risk, beyond its contribution to total physical activity volume.
• Investigating the distinct roles of physical activity volume and intensity is crucial for public health recommendations.

Purpose of the Study:

• To determine if MVPA is associated with a lower mortality risk independently of total physical activity volume.
• To analyze the combined effects of physical activity volume and MVPA contribution on mortality.

Main Methods:

• Meta-analysis of nine prospective cohort studies involving 46,682 adults (mean age: 64 years).
• Physical activity volume and volume-adjusted MVPA were measured using accelerometry and categorized into tertiles.
• Hazard ratios for mortality were estimated using separate and joint models.

Main Results:

• Both higher physical activity volume and a greater contribution from MVPA were independently associated with lower mortality.
• Higher physical activity volume showed a stronger association with reduced mortality risk compared to MVPA's contribution.
• The benefit of higher MVPA intensity on mortality was primarily observed within the middle tertile of total physical activity volume.

Conclusions:

• Total physical activity volume is a more significant predictor of lower mortality risk than the intensity of that activity.
• Encouraging any level of physical activity in middle-aged and older adults can reduce mortality risk.
• Increasing activity intensity provides a marginal additional benefit for mortality reduction.