Secular And Longitudinal Trends In Accelerometer-measured Physical Activity And Sedentary Time In Norwegian Adults

Abstract

Most studies investigating trends in physical activity (PA) and sedentary time have based their results on self-reported measures, which have several known limitations. PURPOSE: The aim of this study was to assess secular and longitudinal trends in accelerometer-measured PA and sedentary time in a population based sample of adults (20-90 years) in Norway. METHODS: For the secular trend analysis, the cohort consisted of 3485 participants (47% men) in 2008-09 (Kan1) and 3173 participants (45% men) in 2014-15 (Kan2). In 2014-15, we localised 3178 (91%) of the original 2008-09 participants whom were invited to participate in the follow-up examination. 1964 participants agreed to participate (62%) of which 1759 (46% men) provided valid data on both occasions. We measured PA and sedentary time using ActiGraph accelerometers. Outcome variables were overall PA level (expressed as mean counts per minute, cpm), time (min/day) spent sedentary (<100 cpm) and in moderate-to-vigorous physical activity (MVPA, >2020 cpm). RESULTS: We found that participants in Kan2 had a significantly higher overall PA level compared with the participants in Kan1 (mean difference: 10 cpm, 95% CI: 2.6, 16.5; P=0.007). There was no difference in time spent sedentary over the six-year period. However, participants in the 2014-15 survey accumulated on average 4 min (95% CI: 2.2, 4.6, P<0.001) more per day in MVPA compared with the participants in the 2008-09 survey. For the longitudinal analysis, we observed no significant changes in overall PA level, time spent sedentary or in MVPA over the six-year period. However, in sub-group analyses, older participants (>65 years) at baseline decreased their overall PA level by 58 cpm (95% CI: −77, −39, P<0.001). Further, women (+23 min/d), men and women aged 35-49 years (+15 min/day) and those >65 years (+23 min/day) significantly increased their time spent sedentary. Moreover, participants aged >65 years at baseline significantly decreased time spent in MVPA (−5 min/day) over the six-year period. CONCLUSIONS: The results indicate that the overall PA level in the population is somewhat higher in 2014-15 than in 2008-09. The longitudinal increase in sedentary time among women and the elderly are of concern and not entirely explained by an ageing effect.