Key result
Atrial pacing increased peak heart rate by 16 beats/min but did not alter peak cardiac output, VO2max, or maximal exercise performance (time to exhaustion 11:21 vs 11:41 min) in healthy cyclists.
Why the study?
Does right atrial pacing improve cardiac output, VO2max, or maximal exercise performance in healthy endurance trained cyclists?
Does right atrial pacing improve cardiac output, VO2max, or maximal exercise performance in healthy endurance trained cyclists?
In healthy endurance-trained cyclists, artificially increasing maximal heart rate via right atrial pacing does not improve peak cardiac output, VO2max, or exercise performance.
No performance benefit from right atrial pacing in healthy cyclists; leaves open whether heart rate augmentation aids patients with chronotropic incompetence.
Aerobic power (VO2max) and exercise performance is limited by a restricted cardiac output during maximal exercise, but the mechanisms restricting cardiac output remain unknown. The attainment of maximal heart rate (HR) could be a factor limiting cardiac output, but the effect of increasing maximal HR has not been investigated in healthy humans. PURPOSE: To investigate the effect of HR pacing on cardiac output, VO2max and exercise performance during maximal cycling. METHODS: We measured systemic and peripheral hemodynamics during incremental (25, 40, 55, 70, 85, 100% of maximal workload (WLmax)) cycling to exhaustion with and without atrial pacing (control HR+ 15-20 beats/min) in 8 endurance trained cyclists (28±2 years, 181±2 cm, 72±2 kg, 66±1 mlO2/min/kg). Data were analyzed by repeated measures one-way ANOVA and Tukey's honestly significant difference (HSD) post hoc procedure. RESULTS: Atrial pacing increased HR by 17±1 beats/min during submaximal cycling and peak HR by 16±3 beats/min (184 ± 2 and 198 ± 4 beats/min in control and pace, respectively) (P<0.05). However, cardiac output and leg blood flow increased similarly in both trials and there was no difference in VO2max or exercise performance (time to exhaustion was 11:41±0.01 and 11:21±0.01 min in control and pace, respectively). In both trials, cardiac output increased linearly until 85% of WLmax but then plateaued in parallel to a drop in stroke volume and an increase in central venous, pulmonary arterial and mean arterial pressures (MAP)(P<0.05). CONCLUSION: The present results demonstrate for the first time that healthy humans can achieve a higher peak HR during atrial pacing and that increasing HR does not increase peak cardiac output, VO2max or maximal exercise performance Supported by Team Denmark
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Munch et al. (2011) studied Healthy humans (n=8). Atrial pacing vs. Without atrial pacing (control) was evaluated on Cardiac output, VO2max and exercise performance (time to exhaustion). Atrial pacing increased peak heart rate by 16 beats/min but did not alter peak cardiac output, VO2max, or maximal exercise performance (time to exhaustion 11:21 vs 11:41 min) in healthy cyclists.
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