Reference ranges for cardiovascular function during exercise: effects of aging and gender on performance

Purpose Real-time (RT) exercise cardiac magnetic resonance imaging (exCMR) provides a highly reproducible and accurate assessment of cardiac volumes during maximal exercise. It has advantages over alternative approaches due to its high spatial resolution and use of physiological stress. Here we define the healthy response to exercise in adults and the effects of age and gender on performance. Materials and Methods Between 2018 and 2021, we conducted CMR evaluation on 169 healthy adults who had no known cardiovascular disease, did not harbour genetic variants associated with cardiomyopathy, and who completed an exCMR protocol using a pedal ergometer. Participants were imaged at rest and after exercise with left ventricular parameters measured using commercial software by two readers. Eight participants were excluded from the final analysis due to poor image quality and/or technical issues. Prediction intervals were calculated for each parameter. Results Exercise caused an increase in heart rate (64±9 bpm vs 133±19 bpm, P < 0.001), left ventricular end-diastolic volume (140±32 ml vs 148±35 ml, P < 0.001), stroke volume (82±18 ml vs 102±25 ml, P < 0.001), ejection fraction (59±6% vs 69±7%, P < 0.001), and cardiac output (5.2±1.1 l/min vs 13.5±3.9 l/min, P < 0.001), with a decrease in left ventricular end-systolic volume (58±18 ml vs 46±15 ml, P < 0.001). There was an effect of gender and age on response to exercise across most parameters. Measurements showed good to excellent intra- and inter-observer agreement. Conclusion In healthy adults, an increase in cardiac output after exercise is driven by a rise in heart rate with both increased ventricular filling and emptying. We establish normal ranges for exercise response, stratified by age and gender, as a reference for the use of exCMR in clinical practice.