Validity and normative data for thirty - second chair stand test inelderly community - dwelling

It is important to establish valid field measures of lower body strength in the elderly as well 2 as provide representative normative values that are culturally specific in order to help health professionals in the risk assessment of this group. A sample of 1038 elderly Hong 4 Kong Chinese undertook a 30 s chair stand test (30CST), with a sub-sample of 143 completing isometric measures of maximal hip flexion and knee extension, plus a habitual 6 physical activity questionnaire. The 30CST was significantly, yet only weakly, correlated with the isometric strength measures (r ~ 0.3-0.4), but accurately discriminated between 8 levels of habitual physical activity and across ages in decades. The normative values generated provide useful data for health screening in this elderly Hong Kong population but 10 do not compare well with their healthier US counterparts. 12 INTRODUCTION Aging is frequently accompanied with a progressive deterioration in physiological function 14 that can often be dependent upon lifestyle characteristics (McArdle et al. 2001). In particular, the maintenance of lower body strength is seen as being an essential part of 16 independent daily living, as it is associated with important activities such as walking, stair climbing, and rising from a seated position, as well as fall-prevention (Jones et al. 1999). 18 Having valid field tests that can be used to monitor community dwelling older adults is important to our understanding of how lower body strength changes with age and to 20 identify those at potential risk of losing their independence or at risk of falling (Wang et al. 2005). 22 Field tests of lower body strength in the elderly have included the time taken to complete 5 24 repetitions (Guralnik et al. 1994) and 10 repetitions (Csuka and McCarty, 1985) of a sit-to3 stand test. Yet these tests have been criticized as being too difficult and failing to 26 discriminate accurately among the elderly (Rikli and Jones, 1999a), as many elderly members of the population are incapable of completing even 5 repetitions (Binder et al. 28 2001). An alternative promoted by Rikli and Jones (2001) quantifies the maximum chairstands completed within 30 s (30CST), and is reliable (intraclass correlation coefficient = 30 0.84-0.92) and a valid measure of lower extremity strength (r = 0.71-0.78) in laboratory settings (Rikli and Jones, 1999a). Yet its suitability as a valid field test and one that can 32 discriminate strength differences among a wide range of true community-dwelling older adults in a field setting is unclear. 34 We aimed to (a) examine the validity of the 30CST in a true field setting, (b) obtain 36 normative data to serve as a benchmark for future Hong Kong studies, and (c) provide data that could be compared with US data (Rikli and Jones, 1999b). 38 SUBJECTS AND METHODS 40 Participants 42 We recruited 1038 elderly volunteers aged 60 to 96 years from the Hong Kong Chinese community, comprising 766 females (mean ± SD: 73.6 ± 7.1 yr; 150.6 ± 6.1 cm; 55.6 ± 44 11.2 kg); and 272 males (73.6 ± 6.7 yr; 162.7 ± 6.4 cm; 63.1 ± 11.1 kg). They were recruited by: (a) random sampling from a list proportional to the total members in each of 46 22 Neighbourhood Elderly Centres across the 18 districts (about 60% of the total); and (b) a multistage random sampling of elderly adults in residential complexes across the 18 48 districts. Each district was clustered and divided into randomly selected sub-districts with floors randomly chosen from each selected residential complex. All households on each 50 selected floor were visited and an interview conducted if a respondent was willing, 4 resulting in an overall response rate of 64%. The inclusion criteria for our sample were 52 elderly persons aged at least 60 years and residing in the community. All participants provided informed consent in accordance with the policies sanctioned by the institute’s 54 ethics committee. 56 Procedures Each participant completed a single 30CST in their own home (Rikli and Jones, 2001) and 58 a Modified Baecke Questionnaire for Older Adults (Voorrips et al. 1991) to separate the participants into 3 levels of habitual physical activity (Low = < 25 percentile; Medium = 60 between 25 – 75 percentile; High = > 75 percentile). A randomly selected sub-sample of 143 participants (113 females: 71.9 ± 7.6 yr, 155.5 ± 6.1 cm, 57.3 ± 10.8 kg, and 30 62 males: 71.7 ± 6.6 yr, 156.0 ± 8.8 cm, 57.5 ± 10.5 kg), also performed two maximal-effort isometric tests of lower body strength: one of hip flexion (HF), and one of knee extension 64 (KE), using the Nicholas Manual Muscle Tester (NMMT: Model 01160: Lafayette Instrument Company, USA), according to the manufacturers instructions and adapted from 66 (Kendall, 1983). Although a field test of hip extension would have been more ideal, we are unaware of any publication using the NMMT to perform this in the field, presumably 68 reflecting to the practical difficulties of this manoeuvre and the potential pain of depressing the NMMT against the superficial hamstrings’ tendons during maximal contractions. 70