Rise more gradual among men, but longer term pattern is similar

November 16, 2020

Science Daily/BMJ

The sharp rise of more than 20 minutes a day in average sedentary time among newly retired women seems to be maintained 2 or more years later, reveals research published online in the journal Occupational & Environmental Medicine.

The rise is more gradual among newly retired men, but the longer term pattern is similar, and a cause for concern for both sexes, given the harmful impact on health of too much time spent sitting down, warn the researchers.

A predominantly sedentary lifestyle is associated with a heightened risk of long term conditions and death. And serial bouts of prolonged sedentary time, lasting 30 minutes or more, are linked to a heightened risk of cardiovascular disease, they highlight.

Previous research indicates that daily total sedentary time tends to increase as people move into retirement, but it's not clear if this includes periods of prolonged sitting time and if such patterns are kept up.

And most studies on long-term changes in sedentary time in the transition to retirement have been based on subjective assessment which is unreliable.

The researchers therefore set out to assess changes in daily total and prolonged sedentary time among older workers transitioning into retirement and to find out if these changes were maintained over the longer term, using objective measurements taken at the same time each year.

They included 689 out of 908 eligible participants in the Finnish Retirement and Aging Study (FIREA), an ongoing long term cohort study of retiring municipal workers in Finland, which began in 2013. Most (85%) of the participants were women, and in admin roles or professional jobs, with an average retirement age of 63.

To track the amount of sedentary time, they each wore an activity tracker (ActiGraph accelerometer) for 10 or more waking hours for 7 consecutive days in each of the few years before, and after, retirement.

To track the amount of sedentary time, participants wore an activity monitor (ActiGraph) for 7 consecutive days and nights, twice before retirement and twice afterwards.

These measurements were used to calculate daily averages of total sedentary time and the amount of time spent in prolonged (30 minutes or more) and in highly prolonged (60 minutes or more) sedentary bouts at each time point.

Among the women, daily total sedentary time, and prolonged and highly prolonged sedentary time didn't change much before retirement, but rose sharply at retirement and then levelled off afterwards.

In the transition period, total sedentary time increased by 22 minutes a day. Prolonged sedentary time rose by 34 minutes a day, while highly prolonged sedentary time rose by 15 minutes a day.

Increases in total and prolonged sedentary time were sharpest among women retiring from manual jobs. These changes persisted 2 or more years after retirement.

Among the men, daily total sedentary time, and prolonged and highly prolonged sedentary time increased in the year leading up to retirement by 21, 23, and 11 minutes, respectively, but no statistically significant changes were observed at retirement.

However, an overall increase in prolonged sedentary time of 33 minutes a day was observed 2 years after retirement. Men had significantly more daily total and prolonged sedentary time than women at all time points.

This is an observational study, so can't establish cause. But, note the researchers: "Our results extend previous knowledge by showing that previously observed higher daily total sedentary time after retirement concerns particularly prolonged sedentary time, which is more harmful for health compared with short sedentary bouts."

By way of an explanation, they suggest that social connections and meaningful activities may diminish after retirement, leading to increased time spent at home and in sedentary activities, such as watching TV. Added to which, physical activity during commuting and lunch breaks no longer interrupt periods of sitting.

Since an increase in prolonged sedentary behaviour increases the risk of cardiovascular disease and mortality dose dependently, retirees should be encouraged to break up sedentary activities," conclude the researchers.

https://www.sciencedaily.com/releases/2020/11/201116184447.htm