Obesity History and Daily Patterns of Physical Activity at Age 60-64 Years: Findings From the MRC National Survey of Health and Development.
BACKGROUND
The aim of this study was to investigate associations of current body mass index (BMI) and obesity history with daily patterns of physical activity.


METHODS
At age 60-64, participants from a British birth cohort study wore accelerometers for 5 days. Accelerometry counts were log-transformed and mean log-counts were used to derive a summary variable indicating total daily log-activity counts. Among those with complete data (n = 1,388) the associations of current BMI and age of first obesity were examined with: (a) total daily log-activity counts and (b) total log-activity counts in four segments of the day.


RESULTS
Higher current BMI and younger age at obesity were strongly associated with lower levels of total daily activity at age 60-64 even after adjustment for sex, socioeconomic factors, and health status. The fully-adjusted mean difference in total daily log-activity counts was -581.7 (95% confidence interval: -757.2, -406.3) when comparing BMI ≥35 kg/m2 with <25 kg/m2, representing an 18.4% difference. Participants who had been obese since early adulthood had the lowest levels of activity (mean difference in total daily log-activity counts was -413.1 (-638.1, -188.2) when comparing those who were obese by age 26 or 36 with those who were never obese, representing a 13.1% difference).


CONCLUSIONS
Obese older adults may require targeted interventions and additional support to improve their daily activity levels. As younger generations with greater lifetime exposure to obesity reach old age the proportion of adults achieving sufficient levels of activity to realize its associated health benefits is likely to decline.
MRC Unit for Lifelong Health and Ageing at UCL, London.
Rachel
R
Cooper
Department of Biostatistics, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.
Lei
L
Huang
MRC Unit for Lifelong Health and Ageing at UCL, London.
Rebecca
R
Hardy
Computer Science Department, United States Naval Academy, Annapolis, Maryland.
Adina
A
Crainiceanu
Laboratory of Epidemiology and Population Sciences, National Institute on Aging, National Institutes of Health, Bethesda, Maryland.
Tamara
T
Harris
Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.
Jennifer A
JA
Schrack
Department of Biostatistics, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.
Ciprian
C
Crainiceanu
MRC Unit for Lifelong Health and Ageing at UCL, London.
Diana
D
Kuh
D061725:Accelerometry; D000203:Activities of Daily Living; D000328:Adult; D000367:Age Factors; D015992:Body Mass Index; D004739:England; D005260:Female; D006306:Health Surveys; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000503:physiopathology*; D012737:Sex Factors
Aging; BMI; Birth cohort; Daily patterns of activity; Life course