Introduction
BLOOD
Blood pressure, grip strength and lung function are commonly assessed in longitudinal population studies. All three are non-invasive measures of physiological function that are practical for a nurse or interviewer to administer in a home or clinical setting using portable equipment. They avoid the subjectivity of self-reports of health, enable researchers and clinicians to track changes in health and function over the life course [Although there have been a number of initiatives to encourage standardisation of these measures [There are existing studies which have shown differences between devices used to measure blood pressure [