Abstract P132: Cardiorespiratory Fitness Has Declined in Individuals Joining a Self-referred Exercise Program Over the Past 45 Years

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Introduction: Cardiorespiratory fitness (CRF) has emerged as a strong predictor of cardiovascular disease (CVD) and all-cause mortality; however, there are limited data to describe population trends in CRF over time. Thus, the purpose of this investigation was to examine changes in objectively measured CRF over the past four decades. We hypothesized that CRF would be progressively lower, by decade, from 1970 to 2015. Methods: We retrospectively examined 3238 individuals who were tested at enrollment into a self-referred university based exercise program. All participants underwent a CVD risk assessment (including measures of blood pressure, blood lipids, and anthropometrics) and a maximal cardiopulmonary exercise treadmill test with measured CRF (i.e., VO2max). Differences in CRF and risk factor variables were analyzed by sex (n=1467 female, n=1771 male) and group based on when testing was conducted (Group A: 1970-1984, n=872; B: 1985-1994, n=1154; C: 1995-2004, n=670; D: 2005-2015, n=542) using a 2x4 factorial analysis of variance. Results: Mean age of participants was higher (P<0.05) in successive cohorts after group B, regardless of sex (41.1±0.3, 41.7±0.3, 45.4±0.5, 47.1±0.6 years for A, B, C, D, respectively). CRF was lower (P<0.05) in successive cohorts after group B for both men (38.1±0.4, 38.0±0.4, 34.8±0.6, 32.8±0.7 ml/kg/min for A, B, C, D, respectively) and women (28.8±0.4, 29.1±0.4, 26.9±0.4, 25.1±0.5 ml/kg/min for A, B, C, D, respectively). Differences in CRF persisted after controlling for age, body weight, and BMI. BMI increased (P<0.05) with each successive cohort up to C for men (25.8±0.2, 27.4±0.2, 29.3±0.3, 29.3±0.3 kg/m2 for A, B, C, D, respectively) and women (24.9±30.3, 25.7±0.2, 27.9±0.3, 29.0±0.4 kg/m2 for A, B, C, D, respectively) and the increase was greater (P<0.05) in women. Resting diastolic blood pressure was lower (P<0.05) with each successive cohort after B (80.1±0.3, 79.5±0.3, 77.8±0.4, 75.6±0.4 mmHg for A, B, C, D, respectively) regardless of sex while no differences were noted for systolic blood pressure. Total cholesterol decreased (P<0.05) with each successive cohort for men (221±2, 211±2, 205±2, 185±2 mg/dl for A, B, C, D, respectively) and women (210±2, 197±2, 199±2, 196±2 mg/dl for A, B, C, D, respectively) with the decrease being greater (P<0.05) in men. Resting heart rate was higher (P<0.05) in cohort D compared to A, B, C in men only (65±1, 68±1, 67±1, 71±1 bpm for A, B, C, D, respectively). Conclusion: Over the past 20 years, adults making the decision to begin an exercise program are doing so at a later age and with a markedly lower CRF (>1.5 METs) than 20-45 years ago. The change in CRF is not fully explained by increasing obesity trends. These data suggest that greater emphasis be given in exercise prescriptions to aggressively improve CRF.