Association of knee-extension strength with instrumental activities of daily living in community-dwelling older adults.
OBJECTIVE
The purpose of the present study was to investigate the relationship between knee-extension (KE) strength and instrumental activities of daily living (IADL), and to examine the risk of IADL disability in relation to KE strength in community-dwelling older adults.


METHODS
The participants were 1235 community-dwelling older adults (261 men and 974 women) in Tokyo who underwent a comprehensive health survey in 2009. The health survey included measurement of KE strength and a questionnaire on the Tokyo Metropolitan Institute of Gerontology (TMIG)-IADL. Pearson product-moment correlation coefficients and partial correlation coefficients were calculated separately for each sex for four parameters representing quadriceps muscle strength and TMIG-IADL. Pearson's χ(2)-test of independence and the Cochran-Armitage test of trend were also carried out to determine the relationship between KE strength and IADL disability.


RESULTS
In women, all correlations between the quadriceps muscle strength parameters and the TMIG-IADL score were statistically significant (P < 0.0005). The significance persisted remained even after factors regarding cognition or depression were taken into consideration. Furthermore, the percentage of female participants with IADL disability was dependent on KE strength; there was an inverse trend between KE strength and the percentage of people with IADL disability. In men, no significant relationship was found between KE strength and IADL.


CONCLUSIONS
KE strength and IADL correlated positively, and the percentage of people with IADL disability decreased with increasing KE strength in women.
Tokyo Metropolitan Geriatric Hospital and Institute of Gerontology, Itabashi-ku, Japan.
Narumi
N
Kojima
Hunkyung
H
Kim
Kyoko
K
Saito
Hideyo
H
Yoshida
Yuko
Y
Yoshida
Hirohiko
H
Hirano
Shuichi
S
Obuchi
Hiroyuki
H
Shimada
Takao
T
Suzuki
D000203:Activities of Daily Living; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D005260:Female; D006306:Health Surveys; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D007717:Knee; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D052097:Quadriceps Muscle / Q000502:physiology*; D012111:Residence Characteristics; D012737:Sex Factors; D014041:Tokyo
activities of daily living; aged; knee; muscle strength; quadriceps muscle