Trajectories of Objectively Measured Physical Activity in Free-Living Older Men

Background: The steep decline in physical activity (PA) among the oldest old is not well understood; there is little information about the patterns of change in PA and sedentary behaviour (SB) in older people. Longitudinal data on objectively measured PA data can give insights about how PA and sedentary behaviour (SB) change with age.

Methods: Men aged 70-90 years, from a UK population-based cohort wore GT3X accelerometer over the hip annually on up to three occasions (56%, 50% and 51% response rates) spanning 2 years. Multilevel models were used to estimate change in activity. Men were grouped according to achieving >=150 minutes/week of MVPA in bouts of >=10 minutes (current guidelines) at two or three time-points.

Results: 1419 ambulatory men had >=600 minutes weartime on >=3 days at >=2 time-points. At baseline, men took 4806 steps/day, and spent 72.5% of their day in SB, 23.1% in light PA and 4.1% in MVPA. Mean change per year was -341 steps, +1.1% SB, -0.7% light PA and -0.4% MVPA each day, (all p<0.001). 76.3%(n=1083) never met guidelines (“stable low”), 7.9% (n=112) consistently met guidelines (“stable high”), 8.2%(n=116) stopped meeting guidelines by the last occasion “decreasers”, and 4.9%(n=69) started meeting guidelines by the last occasion “increasers”. “Decreasers”, spent 69.3% of each day in SB at baseline, which increased by 2%/year (p<0.005), light activity remained at 23.3% (change -0.2%/year, p=0.4), and total MVPA decreased from 7.1% by -1.7%/year, (p<0.001). Number of sedentary bouts >30 minutes increased from 5.1 by 0.1/year(p=0.02).

Conclusions: Among older adults, the steep decline in total PA occurred due to reductions in MVPA whilst light PA is relatively spared and sedentary time and long sedentary bouts increase.