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Updated: Jul 26, 2025
Cardiac Response to β-Adrenergic Stimulation Determined by Pressure-Volume Loop Analysis
Published on: May 19, 2021
Stroke volume response during prolonged exercise depends on left ventricular filling: evidence from a β-blockade
Fabio Giuseppe Laginestra1,2, Ole Kristian Berg3, Stian Kwak Nyberg4
1Department of Circulation and Medical Imaging, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology, Trondheim, Norway.
Insights
Preventing heart rate drift during prolonged exercise with beta-blockers improved stroke volume by increasing end-diastolic volume. This suggests filling time and left ventricular loading conditions are crucial for stroke volume regulation.
Area of Science:
- Exercise Physiology
- Cardiovascular Physiology
- Pharmacology
Background:
- Prolonged moderate-intensity exercise typically causes heart rate (HR) to increase, a phenomenon known as HR drift.
- This HR drift may negatively impact stroke volume (SV) and cardiac output.
- The underlying mechanisms linking HR drift to SV changes, particularly left ventricular function, require further investigation.
Purpose of the Study:
- To investigate the impact of cardiovascular drift on left ventricular volumes and stroke volume during prolonged exercise.
- To determine if preventing HR drift alters left ventricular end-diastolic volume (EDV) and end-systolic volume (ESV), thereby affecting SV.
Main Methods:
- Thirteen healthy young males underwent two 60-minute cycling sessions at 57% maximal oxygen consumption (V̇o2max).
- Participants received either a placebo (CON) or a low dose of beta-1 blockers (BB) to inhibit HR drift.
- Echocardiography was used to measure HR, EDV, and ESV, while other physiological parameters were monitored.
Main Results:
- Beta-blocker administration successfully prevented the typical HR drift observed in the placebo condition.
- Stroke volume (SV) significantly increased by 13% in the BB group, while it remained unchanged in the CON group.
- This SV increase in the BB group was associated with a 4% rise in end-diastolic volume (EDV), indicating improved ventricular filling.
Conclusions:
- Blocking heart rate drift during prolonged exercise enhances end-diastolic volume and stroke volume.
- These findings highlight the critical role of filling time and left ventricular loading conditions in regulating stroke volume during sustained physical activity.
- Cardiovascular drift may impair ventricular filling, leading to reduced stroke volume during endurance exercise.
Abstract:
Prolonged moderate-intensity exercise leads to a progressive upward drift in heart rate (HR) that may compromise stroke volume (SV). Alternatively, the HR drift may be related to abated SV due to impaired ventricular function. The aim of this study was to examine the effects of cardiovascular drift on left ventricular volumes and in turn SV. Thirteen healthy young males completed two 60-min cycling bouts on a semirecumbent cycle ergometer at 57% maximal oxygen consumption (V̇o2max) either under placebo condition (CON) or after ingesting a small dose of β1-blockers (BB). Measurements of HR, end-diastolic volume (EDV), and end-systolic volume were obtained by echocardiography and used to calculate SV. Other variables such as ear temperature, skin temperature, blood pressure, and blood volume were measured to assess potential changes in thermoregulatory needs and loading conditions. HR drift was successfully prevented when using BB from min 10 to min 60 (128 ± 9 to 126 ± 8 beats/min, P = 0.29) but not in CON (134 ± 10 to 148 ± 10 beats/min, P < 0.01). Conversely, during the same time, SV increased by 13% when using BB (103 ± 9 to 116 ± 7 mL, P < 0.01), whereas it was unchanged in CON (99 ± 7 to 101 ± 9 mL, P = 0.37). The SV behavior was mediated by a 4% increase in EDV in the BB condition (164 ± 18 to 170 ± 18 mL, P < 0.01), whereas no change was observed in the CON condition (162 ± 18 to 160 ± 18 mL, P = 0.23). In conclusion, blocking HR drift enhances EDV and SV during prolonged exercise. These findings suggest that SV behavior is tightly related to filling time and loading conditions of the left ventricle.
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