Cardiorespiratory Fitness Estimation by Heart Rate Markers in Young, Sedentary Adults

Abstract

0789 Low levels of cardiorespiratory fitness (CRF) and related autonomic dysfunction have been described as risk factors for cardiovascular events among cardiac patients and healthy adults. CRF can be roughly estimated by easy heart rate (HR) markers such as resting heart rate (HRrest), maximal heart rate (HRpeak), heart rate reserve (HRR) (HRR = HRpeak – HRrest) and heart rate recovery after 1 minute of maximal exercise (HRR1). PURPOSE: To determine the accuracy of common HR markers in predicting field test estimated CRF in young, sedentary, apparently healthy, Hispanic adults. METHODS: 61 (46 female, 15 male) young (19.63 ± 0.81 yrs), Hispanic, volunteer students participated in the study. Subjects initially underwent a pre-participation evaluation. HRrest was measured with the participants recumbent after 5-min rest and was obtained using a heart rate monitor (Polar Electro Oy). CRF was estimated by the 20m-Shuttle run test (20MST). Predicted CRF and HRpeak (heart rate monitor) were recorded at the moment of volitional exhaustion. Immediately after exercise, participants were helped to chairs. HRR1 was defined as the change from HRpeak to HR measured after 1 minute of recovery from exercise. Age-predicted maximal heart rate (PMHR) was 220 beats·min−1- age (yr). Two-tailed Pearson correlation coefficients were performed to determine the level of CRF estimation provided by the HR markers. RESULTS: Predicted CRF by the 20MST was (8.73 ± 1.71 METs). All subjects were free of chronotropic incompetence (defined as HRpeak < PMHR × 0.85). Average HRpeak was (192.09 ± 9.42 beats·min−1) corresponding to a (95.90 ± 4.64 %) of PMHR, according a maximal effort at the 20MST. Average HRrest and HRR1 where 79.88 ± 7.89 beats·min−1 and 27.68 ± 9.95 beats·min−1, respectively. Predicted CRF was significantly correlated (p<0.001) with the HRR (r = 0.46) and HRrest (r = −0.44). HRR1 showed a much lower prediction of CRF (r = 0.25 p = 0.050). No significant correlation was found for HRR1 and CRF in the gender subgroups. HRR was highly correlated with HRrest (r = −0.99, p<0.001). CONCLUSION: In our study group of young sedentary adults, CRF was better predicted by HRR and HRrest than by HRR1. HRR1 after maximal exercise, another indicator of autonomic cardiac control did not improve CRF estimation described by commonly used, HR measurements (HRR and HRrest).