Moderate-to-Vigorous Physical Activity and All-Cause Mortality: Do Bouts Matter?

Area of Science:

• Public Health
• Epidemiology
• Exercise Science

Background:

• Current physical activity guidelines recommend moderate-to-vigorous physical activity (MVPA) in bouts of at least 10 minutes for health benefits.
• It remains unclear whether accumulating the same amount of MVPA in bouts versus sporadically impacts mortality risk.

Purpose of the Study:

• To examine the association between objectively measured physical activity, accumulated with and without bout criteria, and all-cause mortality in US adults aged 40 years and older.
• To determine if MVPA accumulated in bouts reduces mortality risk more than sporadically accumulated activity.

Main Methods:

• Analysis of data from the National Health and Nutrition Examination Survey (2003-2006) and linked death records through 2011.
• Objective measurement of physical activity, defining bouted MVPA in bouts of 5 or 10 minutes with brief interruptions.
• Statistical analysis using hazard ratios to assess mortality risk associated with total and bouted MVPA.

Main Results:

• Mortality risk reductions associated with total MVPA and bouted MVPA were similar.
• Hazard ratios for all-cause mortality ranged from 0.24 to 0.44 across different quartiles of total and bouted MVPA.
• Greater amounts of bouted MVPA did not yield additional mortality risk reductions compared to total MVPA.

Conclusions:

• Mortality risk reductions from MVPA are independent of how the activity is accumulated.
• Findings support the development of physical activity guidelines that do not strictly require MVPA in 10-minute bouts.
• Results can inform clinical practice regarding physical activity recommendations.