Structured Activity Slightly Reduces Sedentary Time Among Seniors

Miriam E Tucker

July 18, 2017

A structured physical-activity program, while improving mobility among older adults, only minimally reduces sedentary time, new research suggests.

The new findings from the Lifestyle Interventions and Independence for Elders (LIFE) study were published July 18 in a research letter in the Journal of the American Medical Association by Amal A Wanigatunga, PhD, MPH, of Johns Hopkins University, Baltimore, Maryland, and colleagues.

The main findings from the randomized, prospective LIFE study in 2014 found that a structured exercise program focused on walking, strength, balance, and flexibility training reduced major mobility disability by 18% among adults aged 70 to 89 years compared with those who received a simple health education program (JAMA. 2014;311:2387-2396).

And in a subsequent recent post hoc analysis, that benefit was found to hold even for the most obese and elderly participants.

Now, these newest data from a post hoc exploratory analysis of LIFE suggest that the benefit may reduce total sedentary time but not prolonged sedentary bouts lasting an hour or longer.

"Additional behavioral approaches are needed to target and reduce sedentary behaviors," Dr Wanigatunga and colleagues conclude.

Sedentary Time Associated With Adverse Health Consequences

Excessive sedentary time is associated with numerous adverse health consequences independent of exercise, particularly in older adults. And prolonged bouts of sedentary time, such as with "binge" television watching, exacerbate the deleterious effects, the authors note.

In the current analysis, total sedentary time was defined as minutes registering fewer than 100 activity counts per minute per waking day, based on accelerometer data. Total sedentary time was divided into bout lengths of ≥ 10 minutes, ≥ 30 minutes, and ≥ 60 minutes.

Of 1341 participants with ≥ 10 hours/day of accelerometer data for ≥ 3 days, 669 had been randomized to the physical-activity program and 672 to health education. They had a mean age of 79 years, 67% were women, and 76% were non-Hispanic white. Mean body mass index was 30 kg/m2 and 42% had a walking speed < 0.8 m/s.

At baseline, participants wore the accelerometer for a mean 870 minutes/day, spending 647 minutes/day in total daily sedentary time. By 6 months, the physical-activity group had accrued 630 total sedentary min/day compared with 639 minutes/day for controls. The 9-minute difference was significant (P = .002) and persisted over the following 18 months, although both groups grew increasingly sedentary over time. 

Mean baseline time spent in the different sedentary bout lengths was 488 minutes/day for ≥ 10 minutes, 296 minutes/day for ≥ 30 minutes, and 145 minutes/day for ≥ 60 minutes.

At 6 months, the physical-activity group had accumulated 12 fewer minutes of time in sedentary bouts of ≥ 10 minutes (P = .003) and 9 fewer minutes in sedentary bouts of ≥ 30 minutes (P = .02). But there was no difference in bouts of ≥ 60 minutes, and both groups became increasingly sedentary across all bouts.

However, it's unclear whether the changes in sedentary time were clinically meaningful, Dr Wanigatunga and colleagues conclude.

The study was funded by the National Institutes of Health. The authors have reported no further relevant financial relationships.

JAMA. Published July 18, 2017. Abstract

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