Classification of pro-inflammatory status for interleukin-6 affects relative muscle strength in obese elderly women.
BACKGROUND
Obesity, defined by an excess amount of body fat or a percent body fat higher than 30 % for women is a complex chronic disorder with multifactorial etiology and is accompanied by chronic low-grade inflammation, which results in elevated pro-inflammatory cytokines.


AIMS
The aim of this study was to compare muscle strength between high and low pro-inflammatory status in obese elderly women and to verify the relationship of IL-6 with muscle strength and fat-free mass.


METHODS
Eighty-nine elderly women (age 69.47 ± 6.07 years; body mass 64.70 ± 12.04 kg; height 1.52 ± 0.06 m; body mass index 27.78 ± 4.75 kg/m(2)) were divided into two groups: high and low inflammatory status for IL-6. Lower limb muscle strength was tested using bilateral leg extension with the ten repetitions maximum test, IL-6 was measured by ELISA and body composition by dual-energy X-ray absorptiometry.


RESULTS
Women classified from the high pro-inflammatory status presented lower relative muscle strength (P = 0.056) when compared with the low inflammatory status group, with no differences for absolute muscle strength (P = 0.18). There was a significant negative correlation of IL-6 with relative muscle strength (P = 0.03, R = -0.22) and a considerable trend toward significance (P = 0.06, R = -0.19) and negative association with fat-free mass (P = 0.84, R = -0.02).


CONCLUSIONS
This study provides insights that a high pro-inflammatory status in sedentary obese elderly women might impair muscle strength and negatively affect fat-free mass. Thus, elderly women classified with high pro-inflammatory status for IL-6 should receive further health care attention to prevent this deleterious condition.