Bidirectional associations of accelerometer-derived physical activity and stationary behavior with self-reported mental and physical health during midlife

BackgroundModerate-to-vigorous intensity physical activity (MVPA) is associated with favorable self-rated mental and physical health. Conversely, poor self-rated health in these domains could precede unfavorable shifts in activity. We evaluated bidirectional associations of accelerometer-estimated time spent in stationary behavior (SB), light intensity physical activity (LPA), and MVPA with self-rated health over 10years in in the CARDIA longitudinal cohort study.MethodsParticipants (n=894, age: 45.13.5; 63% female; 38% black) with valid accelerometry wear and self-rated health at baseline (2005-6) and 10-year follow-up (2015-6) were included. Accelerometry data were harmonized between exams and measured mean total activity and duration (min/day) in SB, LPA, and MVPA; duration (min/day) in long-bout and short-bout SB (>= 30min vs. <30min) and MVPA (<greater than or equal to>10min vs. <10min) were also quantified. The Short-Form 12 Questionnaire measured both a mental component score (MCS) and physical component score (PCS) of self-rated health (points). Multivariable linear regression associated baseline accelerometry variables with 10-year changes in MCS and PCS. Similar models associated baseline MCS and PCS with 10-year changes in accelerometry measures.ResultsOver 10-years, average (SD) MCS increased 1.05 (9.07) points, PCS decreased by 1.54 (7.30) points, and activity shifted toward greater SB and less mean total activity, LPA, and MVPA (all p<0.001). Only baseline short-bout MVPA was associated with greater 10-year increases in MCS (+0.92 points, p=0.021), while baseline mean total activity, MVPA, and long-bout MVPA were associated with greater 10-year changes in PCS (+0.53 to +1.47 points, all p<0.005). In the reverse direction, higher baseline MCS and PCS were associated with favorable 10-year changes in mean total activity (+9.75cpm, p=0.040, and+15.66cpm, p<0.001, respectively) and other accelerometry measures; for example, higher baseline MCS was associated with -13.57min/day of long-bout SB (p<0.001) and higher baseline PCS was associated with +2.83min/day of MVPA (p<0.001) in fully adjusted models.Conclusions The presence of bidirectional associations between SB and activity with self-rated health suggests that individuals with low overall activity levels and poor self-rated health are at high risk for further declines and supports intervention programming that aims to dually increase activity levels and improve self-rated health.