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Physical activity measures in the 1970 British Cohort Study

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Learn about the 1970 British Cohort Study (BCS70) and its measurement of physical activity

Longitudinal study description

The 1970 British Cohort Study (BCS70) began as The British Births Survey and was later renamed Child Health and Education Study before settling on its current name. The initial birth survey involved 17,198 babies born in a single week in April in 1970. Like the older NCDS study, it was initiated with a strong focus on child health, before later including many other areas such as social, psychological, educational and economic outcomes. A total of ten main sweeps of data collection have been carried out, with follow-ups after the birth survey at ages 5, 10, 16, 26, 30, 34, 38, 42 and 46y. In childhood, parents were main reporters on their children, with teachers also providing information, in addition to child tests and school medical examinations.

Study members themselves first completed questionnaires at age 16y, and in adulthood they participated through in-person or telephone interviews, or postal surveys. The most recent core BCS70 sweep, which included a full range of biomeasures, was completed in 2018 at age 46-48y and achieved a total of 8,581 participating study members. At the time of writing, data collection at 51y is ongoing [102].

The BCS70 was included in the COVID-19 waves of data collection in the British birth cohorts. A web-based interview was carried out in May 2020 (Wave 1), September-October 2020 (Wave 2), and February-March 2021 (Wave 3), when BCS70 members were aged 50.

Physical activity overview (5 to 50y)

BCS70 contains childhood and adult self-reported measures across physical activity domains (from 5-50y). Leisure time was measured at ages 5, 10, 16, 30, 34, and 42y; active travel was measured at age 34y; domestic activities were measured at age 16 and 46y in the core waves and 50y in the COVID waves; and sedentary behaviour was measured at ages 5, 10, 16, 42, and 46y and at 50y in the COVID waves.

In terms of comparability across sweeps in this longitudinal study, overall engagement in leisure time can be compared across ages 5, 10, 16, 30, 34, 42, and 46y while intensity can be compared across ages where information was collected on specific activities/sports (i.e. ages 30, 43, 46y). Additional questions with frequency and duration responses varied somewhat between questions. Active travel was only measured at one age and therefore cannot be compared across sweeps. The frequency of domestic activity has been measured at three ages but there is different information on duration and intensity so these activities may not be comparable on these metrics. Finally, sedentary behaviour provided comparable measures of duration (hr/day) in childhood and adulthood (ages 5, 10, 16, 42, 46, and 50y).

Additionally, objective measures of activity expenditure (kJ/kg/day) were captured at ages 46-48y using the ActivPal accelerometer (PAL technologies Ltd, Glasgow, Scotland). Derived data from the accelerometry measurements have been released, which describe the time spent sitting, standing, or carrying out activity. Except from sitting being a sedentary behaviour, standing and activity bouts cannot be categorised into leisure or occupation etc. like other physical activity measures because the accelerometer only measures the movement and not purpose of the activity. Values are available for each day the cohort member wore the device, as well as a daily average calculated from all the days of wear.

Data access

BCS70 data are freely accessible to bona fide researchers by applying through the UK Data Service. More information on BCS70 is available on the CLS website.

Learn about the other studies covered by this guide and their measurement of physical activity:

Explore the measures by physical activity domain and their cross-study comparability:

Further information:

This page is part of the CLOSER resource: ‘Physical activity across age and study: a guide to data in six CLOSER studies’.