The mediating role of C-reactive protein and handgrip strength between obesity and walking limitation.

OBJECTIVES

To study the association between different obesity indicators and walking limitation and to examine the role of C-reactive protein (CRP) and handgrip strength in that association.

DESIGN

A cross-sectional, population-based study.

SETTING

The Health 2000 Survey with a representative sample of the Finnish population.

PARTICIPANTS

Subjects aged 55 and older with complete data on body composition, CRP, handgrip strength, and walking limitation (N=2,208).

MEASUREMENTS

Body composition, anthropometrics, CRP, medical conditions, handgrip strength, and maximal walking speed were measured in the health examination. Walking limitation was defined as maximal walking speed less than 1.2 m/s or difficulty walking half a kilometer.

RESULTS

The two highest quartiles of body fat percentage and CRP and the two lowest quartiles of handgrip strength were all significantly associated with greater risk of walking limitation when chronic diseases and other covariates were taken into account. In addition, high CRP and low handgrip strength partially explained the association between high body fat percentage and walking limitation, but the risk of walking limitation remained significantly greater in persons in the two highest quartiles than in those in the lowest quartile of body fat percentage (odds ratio (OR)=1.75, 95% confidence interval (CI)=1.19-2.57 and OR=2.80, 95% CI 1.89-4.16). The prevalence of walking limitation was much higher in persons who simultaneously had high body fat percentage and low handgrip strength (61%) than in those with a combination of low body fat percentage and high handgrip strength (7%). Using body mass index and waist circumference as indicators of obesity yielded similar results as body fat percentage.

CONCLUSION

Low-grade inflammation and muscle strength may partially mediate the association between obesity and walking limitation. Longitudinal studies and intervention trials are needed to verify this pathway.