Examining the associations between different physical fitness phenotypes and cardiovascular risk factors in older females
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Abstract
Cardiovascular disease (CVD) is the leading cause of death in older adults. While it is known that having both high muscle strength (MS) and cardiorespiratory fitness (CRF) is associated with a lower risk of CVD, no studies have addressed the differences in CVD risk factors between older females with different physical fitness phenotypes, such as high MS but poor CRF. I hypothesized that different CVD risk factors will be prevalent across groups with different physical fitness phenotypes. To test this, I performed a secondary analysis of data from 985 females aged 55 and older with no previous history of CVD. Participants were assigned to one of 5 groups based on their grip strength (GS) and 6MWT scores: 1) High CRF-High MS [HiFit-HiSt]; 2) High CRF-Low MS [HiFit-LoSt]; 3) Normal CRF-Normal MS [NoFit-NoSt]; 4) Low CRF-High MS [LoFit-HiSt]); and 5) Low CRF-Low MS [LoFit-LoSt]). The differences between groups were examined using a one-way ANOVA for continuous variables with Tukey’s Post-Hoc. A linear regression model adjusted for age and BMI was created to assess the influence of CRF and MS on each CVD risk factor, using 6MWT and GS values as continuous predictors. The main findings of the ANOVA were that, in older females with no pre-existing CVD, the groups that had high CRF (i.e. both HiFit-LoSt and HiFit-HiSt) had lower CVD risk factors than the other 3 groups. After comparing estimated marginal means in the generalized linear regression model, significant differences in the FRS score were only found between the HiFit-LoSt and LoFit-LoSt groups (8.5 ± 0.4 vs. 11.2 ± 0.6, p = 0.011). Additionally, a relationship was found between higher CRF and decreased FRS (β = -0.008, p = 0.003), triglycerides (β= -0.001, p = 0.036), resting SBP (β = -0.018, p = 0.036), pulse pressure (β = -0.016, p = 0.009), and post-exercise SBP (β = -0.029, p = 0.017), as well as increased large artery elasticity (LAE) (β = 0.006, p = 0.002). Higher MS was only associated with increased LAE (β = 0.091, p < 0.001) and Small Artery Elasticity (SAE) (β = 0.060, p < 0.001).