Table 4.
Multiple linear regression models of inflammation versus physical function, muscle strength and specific strength (linear models)
| Physical function & strength | Markers of inflammation | β (SEE) | Standardized β | P value for β | R2 |
|---|---|---|---|---|---|
| Six-minute walk test [6MWT]: distance (m) | TNFα (pg/ml) | −2.74 (2.98) | − 0.064 | 0.36 | 42 % |
| Gait speed (m/s) | TNFα (pg/ ml) | 0.01 (0.01) | 0.10 | 0.25 | 22% |
| hs-CRP (mg/ L) | −0.01 (0.01) | − 0.06 | 0.49 | 20% | |
| IL-6 (pg/ ml) | −0.001 (0.01) | −0.01 | 0.87 | 21% | |
| Chair sit and reach [CSR] (cm) | hs-CRP (mg/ L) | −0.43 (0.47) | − 0.086 | 0.36 | 13 % |
| IL-6 (pg/ ml) | −2.74 (1.50) | − 0.160 | 0.07 | 14 % | |
| Knee extension strength (kg) | TNFα (pg/ ml) | 0.04 (1.25) | 0.002 | 0.97 | 36 % |
| hs-CRP (mg/ L) | 1.82 (1.28) | 0.120 | 0.16 | 36 % | |
| Hand grip strength (kg) | TNFα (pg/ ml) | 0.10 (0.23) | 0.018 | 0.68 | 77 % |
| Specific strength | |||||
| Lower extremity specific strength (kg/ L)a | TNFα (pg/ ml) | 0.72 (3.75) | 0.02 | 0.85 | 9% |
| hs-CRP (mg/ L) | 4.84 (3.79) | 0.12 | 0.20 | 10% | |
Note: Only models with a linear association between the inflammatory marker and physical function, and analyzed by multiple linear regression are shown in this table. Models for physical function and strength were adjusted for race, sex, moderate to vigorous intensity physical activity (MVPA), arm lean mass (hand grip strength) or thigh skeletal muscle (all other physical function scores), and age (gait speed). The model for specific strength was adjusted for race, sex and MVPA. With the exception of the model for gait speed, age was not included as a covariate as it did not improve the models' ability to explain the variance in physical function and was not significantly associated with physical function in these models. IL-6 was logarithmically transformed to attain normality. For the chair sit and reach test, lower scores indicate a poorer performance; SEE, Standard error of the estimate; TNFα, tumor necrosis factor-α; hs-CRP, high sensitivity C-reactive protein: IL-6, interleukin-6; a. Lower extremity specific strength assessed as the ratio of isometric knee extension strength (kg) to thigh skeletal muscle mass (L) by magnetic resonance imaging (MRI).