The Association between Muscular Strength and C-reactive Protein among Post-Menopausal Women: Effect Modification by Hormone Replacement Therapy

Previous studies suggest that the inflammatory marker C-reactive protein (CRP) may be elevated in post-menopausal women taking hormone replacement therapy (HRT). Muscular strength is associated with more favorable CRP profiles. However, this association has not been examined among post-menopausal women on HRT. PURPOSE: This study aims to examine the association of lower leg strength and CRP while considering potential effect modification by HRT using a representative sample of U.S. adults. METHODS: The final sample (n=1,238) included post-menopausal women (≥50 years) who participated in the 1999-2002 National Health and Examination Survey (NHANES). CRP was examined continuously and categorically (/dl vs 3-10 mg/dl). Lower leg strength was assessed using a Kin Kom MP isokinetic dynamometer and categorized into weighted tertiles. Linear and logistic regression were used to examine the association between leg strength and CRP across participants on and not on HRT. RESULTS: Table 1 shows lowered CRP levels for strength tertile 2 (p=0.01) and tertile 3 (p=0.0029) for women on HRT, not adjusted for waist circumference (WC). CRP was also lowered in Tertile 3 compared to Tertile 1 for women not on HRT for Model 1 (p=0.005). Model 2 in Table 1 shows clinical significance in CRP reduction for women on HRT while adjusting for WC (p=0.06). In table 2, there was a 65% reduction in odds for women on HRT in tertile 3 when not adjusted for WC (p=0.03), and clinical significance for a 47% reduction in odds of elevated CRP for women on HRT in tertile 3, when adjusting for WC (p=0.06). CONCLUSION: These findings suggest that level of strength has a significant association with CRP values, regardless of HRT status. The association was mediated by WC, so future studies should examine the association between WC, inflammation, and strength, as well as using different measurements of strength.