Effects of Sedentary Behavior, Physical Activity, Frequency of Protein Consumption, Lower Extremity Strength and Lean Mass on All-Cause Mortality.

Background: No study has evaluated the potential independent and cumulative effects of physical activity, sedentary behavior, daily frequency of protein consumption, lean mass and muscular strength on mortality risk.

Methods: Data from the 1999-2002 NHANES were utilized (N = 1,079 adults 50-85 yr), with follow-up through 2011. Leg lean mass was estimated from DXA scans. Knee extensor strength was assessed using the Kin Com MP dynamometer. Physical activity and sedentary behavior were assessed via questionnaire, with the number of meals/day of ≥30 g of protein/meal assessed via a "multiple pass" 24-hour dietary interview. An index score was created (range = 0-5) indicating the number of these health characteristics each participant had.

Results: Only less sedentary behavior was independently associated with reduced mortality risk (HRadjustment = 0.46; 0.32-0.66). After adjustments, and compared to those with an index score of 0, those with an index score of 1, 2 and 3+, respectively, had a 34%, 49%, and 57% reduced risk of all-cause mortality.

Conclusion: While considering physical activity, sedentary behavior, daily protein frequency consumption, lean mass and muscular strength, only sedentary behavior was independently associated with mortality risk among older adults.