Association Between Midlife Strength On Long Term Risk For Heart Failure: Cooper Center Longitudinal Study

Low midlife cardiorespiratory fitness and high body mass index (BMI) are independently associated with a higher risk for heart failure (HF) in later life. However, these mechanisms remain incompletely understood. Low muscular strength is associated with lower fitness, and prior research has reported inconsistent associations between low strength and HF risk. PURPOSE We sought to characterize the association between low muscular strength and HF after accounting for fitness, obesity, and other confounders. METHODS We included 7792 participants (16% women, baseline age 42.5 years) enrolled in the Cooper Center Longitudinal Study who also achieved Medicare eligibility between 1999-2019. Strength was measured using a 1 repetition maximum bench and leg press which was indexed to body weight and normalized for age and sex. Fitness was measured from treadmill exercise time (modified-Balke protocol). Both fitness and strength were analyzed as categorical (Quintile 1 vs. 2-3 vs. 4-5) and as continuous variables (fitness in METs, strength as average bench and leg press z-score). BMI was determined from measured height and weight. The primary outcome was incident HF hospitalization defined from Medicare claims. A modified Cox model was used to estimate independent associations between strength, fitness, and BMI on incident HF. RESULTS We observed 313 incident HF events. Compared to high strength, low strength was associated with a higher risk for HF (5.58 vs 3.64 per 1000 person-years). Similar findings were observed for fitness. In multivariable-adjusted models accounting for age and sex, higher BMI and lower fitness were associated with a higher risk for HF; however, strength was not (see Figure). Formal interaction testing was not significant, suggesting no heterogeneity in the association between strength and HF risk. CONCLUSION These findings suggest that low midlife strength is not associated with incident HF after accounting for measures of fitness and obesity.