Serum C-reactive protein even at very low (<1.0 mg/l) concentration is associated with physical performance in a community-based elderly population aged 70 years and over.
BACKGROUND
Although several studies have reported that C-reactive protein (CRP) is associated with physical performance, few studies have evaluated the relationships between CRP and physical performance among subjects who had a very low range of CRP. Therefore, it is still unclear whether a lower CRP is favorably associated with physical performance even within a very low range.


OBJECTIVE
The aim of this study was to investigate the relationships between CRP and physical performance among a Japanese population with a low serum CRP concentration (CRP <1.0 mg/l).


METHODS
We designed a cross-sectional survey for 775 persons aged 70 years and older living in Japan. High-sensitivity CRP was measured using a nephelometric method. The subjects whose serum CRP concentrations were higher than 10.0 mg/l were excluded. Physical performance was assessed using a 10-meter maximum walk test, leg extension power, and a timed 'up and go' test.


RESULTS
The median value (interquartile range) of CRP was 0.55 (0.29-1.20) mg/l. After adjustment for potential confounding factors, an inverse relation of CRP with the 10-meter maximum walk test and leg power was observed in all subjects (p for trend = 0.10 and 0.04, respectively). For subjects who had a CRP <1.0 mg/l, these inverse relations were unchanged (p for trend = 0.03 and 0.02, respectively).


CONCLUSIONS
Serum CRP concentration is favorably related to physical performance, even within a very low range in a community-based elderly population aged 70 years and over. The findings suggest that maintaining as low CRP levels as possible may potentially maintain better physical performance.
Niu
Kaijun
K
Department of Medicine and Science in Sports and Exercise, Tohoku University Graduate School of Medicine, Aoba-ku, Sendai, Japan. ggg@mail.tains.tohoku.ac.jp
Hozawa
Atsushi
A
Guo
Hui
H
Kuriyama
Shinichi
S
Ebihara
Satoru
S
Yang
Guang
G
Ohmori-Matsuda
Kaori
K
Nakaya
Naoki
N
Takahashi
Hideko
H
Fujita
Kazuki
K
Wen
Shirong
S
Arai
Hiroyuki
H
Tsuji
Ichiro
I
Nagatomi
Ryoichi
R
D000203:Activities of Daily Living; D000368:Aged; D000369:Aged, 80 and over; D002097:C-Reactive Protein / Q000378:metabolism*; D003430:Cross-Sectional Studies; D005080:Exercise Test; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D006801:Humans; D007564:Japan; D007866:Leg / Q000502:physiology; D016015:Logistic Models; D008297:Male
D002097:C-Reactive Protein