Physical capability refers to an individual’s capacity to undertake the physical tasks of daily living. It can be assessed in a number of ways including objectively using tests of muscle strength and physical performance and by self reports of everyday function.
In the NSHD, muscle strength has been assessed through measurement of grip strength, and physical performance has been measured using standing balance and chair rise tests. In addition, study members’ self reports of their ability to perform everyday daily functions including being able to wash and dress oneself, go shopping and cook have also been assessed.

Muscle strength and physical performance

During the visits in 1999, 2006-10 and 2014-16, nurses measured study members’ performance in three tests:

  • grip strength [measured using an electronic dynamometer1) twice in each hand, except for age 60-64 when three recordings were taken]
  • chair rises [time taken to rise from a chair and sit back down again 10 times as fast as possible]
  • standing balance [measured as the time, up to a maximum of 30 seconds, that study participants could stand on one leg with their eyes open and also with their eyes closed]

In addition, in 1999 (age 53) 202 study participants participated in a sub-study at one of five clinics where leg extensor power was measured.

In 2006-10, a timed “get up and go” was added - study members had to get up from a chair, walk 3m, turn around, walk back and sit back down. In 2014-16, to make this part of the test more accessible for a home environment, the walking distance was shortened to 2.44m (8ft) and the study members were no longer required to stand up and sit down. Walking speed (m per sec) have been derived.

Composite summary performance scores have been derived. In addition, variables are available which explain the reasons for missing data (given this may be caused by the study member’s inability to perform the tests).

Activities of daily living (ADLs)

Questions on ADLs were asked for the first time in 1982 (36 years), at the end of self-completion questionnaire ‘C’. These were broad questions and focused on difficulties with activities that had lasted for more than two weeks.
During further sweeps at age 43, 53, 60-64 and 68-70 years the assessment of functional impairment used the same or similar criteria as that used in the OPCS 1988 disability survey2).

The main categories of ADL are as follows:

  • locomotor activities [for example, walking for a quarter of a mile on the level, going up or down steps or stairs, bending down and straightening up without holding on to anything, and falling or keeping balance]
  • using arms to reach or stretch for things
  • using hands to hold, grip or turn things
  • carrying out a number of personal self-care activities

These questions were based on the OPCS postal questionnaire.

During the home interview at age 43 years, ADL questions were asked in two stages; firstly study members completed a general Disability Checklist screening questionnaire (questionnaire 'B'), with a more detailed, separate Disability Questionnaire filled in if they answered yes to any item in the original checklist (questionnaire 'C'). Data have been used to generate four summary domain variables: locomotion, reaching & stretching, dexterity & personal care.

During the home interviews at 53, 60-64 and 68-70 years, the screening questions for the OPCS classification were repeated followed by a question to distinguish severe or mild disability as defined in the OPCS survey.

A summary set of variables has been created at 43 and 53 years to look at change between these ages. As the complete OPCS set of questions was not asked at age 53 years or later, only these more limited summary measures are available at the earlier two time points.

Key publications

Cooper R, Mishra G and Kuh D Physical activity across adulthood and physical performance in mid-life: Findings from a British birth cohort study American Journal of Preventive Medicine 2011;41(4):376-384

Kuh, D., Bassey, E.J., Butterworth, S., Hardy, R., Wadsworth, M.E.J. Grip strength, postural control and functional leg power in a representative cohort of British men and women: associations with physical activity, health status and socioeconomic conditions The Journal of Gerontology: Medical Science, 2005 60A(2), 225- 232.

Obtaining the physical capability standard variables

  • You can obtain a list of the standard topic variables to use in an NSHD data sharing request by selecting the link below.

Please Note that the standard basket only contains physical performance variables, rather than ADL measures. The ADL variables are all standalone, for individual tasks, and summary measures have not been derived. The most recent ADL variables can be found in data libraries 'PhysCap09', 'PhysCap15' and 'PhysAct15'. Please use these as a starting point for further investigation.

Many more physical performance variables are available, for example different recodes of the measures, converting 'times' to 'speeds'. The physical performance variables are well-documented on Skylark, if you click on a variable there will be a link to the appropriate pdf. Enquirers are strongly advised to view this information before deciding which variables to use. The recent physical performance measures can be found in libraries 'PhysPerf09' and 'PhysPerf15'.

HTML version of the standard variables to view

For the 1999 and 2006-10 data collections the dynamometer used was the Nottingham Electronic MK3. This was changed to the Jamar Digital for the 2015-16 home visit.
Martin et al, OPCS surveys of disability in Great Britain - report 1: The prevalence of disability among adults, 1988
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