Estimated activity patterns in British 45 year olds: cross-sectional findings from the 1958 British birth cohort.

OBJECTIVE: To investigate patterns of, and associations between, physical activity at work and in leisure time, television viewing and computer use.
SUBJECTS: 4531 men and 4594 women with complete plausible data, age 44-45 years, participating in the 1958 British birth cohort study.
METHODS: Physical activity, television viewing and computer use (hours/week) were estimated using a self-complete questionnaire and intensity (MET hours/week) derived for physical activity. Relationships were investigated using linear regression and chi(2) tests.
RESULTS: From a target sample of 11,971, 9223 provided information on physical activity, of whom 75 and 47% provided complete and plausible activity data on work and leisure time activity respectively. Men and women spent a median of 40.2 and 34.2 h/week, respectively in work activity, and 8.3 and 5.8 h/week in leisure activity. Half of all participants watched television for > or =2 h/day, and half used a computer for <1 h/day. Longer work hours were not associated with a shorter duration of leisure activity, but were associated with a shorter duration of computer use (men only). In men, higher work MET hours were associated with higher leisure-time MET hours, and shorter durations of television viewing and computer use. Watching more television was related to fewer hours or MET hours of leisure activity, as was longer computer use in men. Longer computer use was related to more hours (or MET hours) in leisure activities in women.
CONCLUSIONS: Physical activity levels at work and in leisure time in mid-adulthood are low. Television viewing (and computer use in men) may compete with leisure activity for time, whereas longer duration of work hours is less influential. To change active and sedentary behaviours, better understanding of barriers and motivators is needed.