Exercise‐based cardiac rehabilitation is associated with a normalization of the heart rate performance curve deflection

Abstract

The heart rate (HR) rises with increased power output, whereby in most healthy individuals, the slope of HR levels off with higher intensity. This corresponds to a downward deflection of the heart rate performance curve (HRPC). Conversely, in patients after myocardial infarction, an upward HRPC deflection is frequently observed that is especially pronounced in patients with compromised left ventricular ejection fraction. To investigate whether regular endurance training during cardiac rehabilitation might normalize HRPC, data of 128 male patients were analyzed. All patients performed three exercise tests: at baseline, after 6 weeks, and after 1 year. Ninety‐six patients exercised regularly according to guidelines for 1 year (training group, TG), and 32 stopped after 6 weeks (control group, CG). Similarly, upward‐deflected HRPCs were observed at baseline and after 6 weeks in both groups. After 1 year, TG patients had less upward‐deflected HRPCs compared with CG ones, corresponding to a partial normalization. Greater changes in HRPC deflection were associated with larger improvements in cardiorespiratory fitness. Our results might indicate improved myocardial function due to long‐term rehabilitation. Further, HRPC alterations over time should be considered when prescribing exercise intensities using a target HR, as deflection flattening might render the intensity of corresponding exercise insufficient.

Heart Rate Performance Curve Is Dependent on Age, Sex, and Performance

“…Although most young healthy subjects (∼86%) showed a regular deflection of the HRPC, in this homogenous group of 227 (23 ± 4 years) trained male sports students an inverse deflection was found in in 7.9% cases and a linear time course was found in 7.9% of subjects in this study (1). Additional information is sparse and only one study by Heber et al (7) presented data on HRPC deflection in 128 patients during cardiac rehabilitation, however did not show the distribution among subjects. Pokan et al (8) was the first to show increasing atypical HR curves in older patients suffering from heart disease.…”

“…Such a pathophysiological value of the HRPC can also be found in patients after myocardial infarction, who frequently present an upward deflection in incremental exercise tests (11). A normalization of the HRPC was found with increasing cardiorespiratory fitness after a 1 year exercise-based cardiac rehabilitation program independent from medication (7).…”

“…Also aerobic exercise training was shown to reduce circulating catecholamine's (33), which counteracts reduced β-adrenergic density due to overactivation of the sympathetic nervous system and concomitant chronic catecholamine stimulation (34). Thus, sensitization of the β1-receptor through regular exercise might normalize atypical HRPC provoked by chronic stress due to diseases such as type 1 diabetes (10) or cardiovascular disease (11) as shown recently (7).…”

“…Toward an age of 50 years changes in the degree of the HRPC deflection and the number of atypical curves were stronger compared to >50 years. Sparse studies showed that patients with cardiovascular disease mostly displayed an upward deflection of the HRPC (7,11), prescribed also in people with type 1 diabetes (10), however no studies in age heterogenous healthy subject have been presented so far.…”

Cardioprotective effects of high‐intensity interval training are mediated through microRNA regulation of mitochondrial and oxidative stress pathways

“…Using echocardiography, we observed the HIIT group had increased FS compared with sedentary and ET groups (Table ). EF is the percentage of blood that is pumped out of the left ventricle with each contraction and is an important measurement in analyzing heart function (Heber et al, ). A study that correlates with our findings was performed by Saadatnia et al who show EF to be increased in healthy untrained men after 10 weeks of HIIT and also report increases in left ventricular mass (Rashidlamir, ).…”