Indirectly determined maximal cardiac output in men and women with different physical activity
Authors: Jaroslav Novák , Stork Milan 
Published: January 2024

Introduction: Maximal cardiac output (COmax) is one of the most important functional parameters related to cardiorespiratory capacity (VO2max) and physical fitness. In clinical medicine, low COmax values are a risk factor for imminent heart failure. Conversely, high COmax values are a prerequisite for achieving high performance in sports, especially in endurance disciplines. Methods: To determine the COmax, we used our own modification of the COmax calculation from the VO2max values obtained during the spiroergometric examination (Stork et al. - 1). Our work is based on the findings of Stringer et al (2), which documented a very close correlation between COmax values obtained by calculation and COmax values obtained by the classical method according to Fick's principle. Subjects: From our 20-year examination database, we included in this study 641 men (M) and 164 women (F) over 19 years of age who completed a stress test on a bicycle ergometer with a graded load to the maximum. To calculate COmax, we used the equation with which we have already worked in several of our earlier studies. We have divided the files into three groups according to different physical activity: group A included well-trained endurance-athletes, who had several years of sports training at the time of the examination. Group B included subjects who engaged in physical activity only in their free time without competing in any sports competition. Subjects with various health problems who either never played any sport at all or ended their sports career many years ago, were included in group C. Results: COmax in group M-A (n=462, COmax=28.38±4.47 l/min) was significantly higher than in groups M-B (n=143, COmax=19.4±3.7 l/min) and M-C (n=36, COmax=18.4±5.9 l/min). It was the same with the women's groups. COmax values in group F-A (n=58, COmax=20.7±3.7 l/min) were significantly higher than in groups F-B (n=88, COmax=12.8±2.3 l/min) and F-C (n=18, COmax=12.1±2.0 l/min). There were no significant differences in both M and F between groups C and D. The same findings were found when comparing maximal stroke volume (SVmax) values. Conclusions: Movement activity is a condition for the development and maintenance of the adaptive abilities of the cardiorespiratory system. The parameters measured in recreational sportsmen correspond to the average of a healthy average fit population. If physical activity is not part of a healthy lifestyle and, in addition, there are health problems (in our groups C obesity and resting and exertional chest pains are the most common), in many subjects from our groups C the COmax parameters are significantly below average and close to the level characterizing the NYHA-1 to NYHA-2 group according to cardiology classification. The results show, on the one hand, how important factor in health prevention is regular physical activity, and, on the other hand, the applicability of our modified method to determine non-invasively the maximum cardiac output. References: 1. Stork M., Novak J., Zeman V.: Noninvasive cardiac output estimation evaluated from spiroergometric stress test. International Conference on Applied Electronics. Zapadoceska Univerzita, Plzen, 2010: 331-334. 2. Stringer W.W., Hansen J.E., Wasserman K.: Cardiac output estimated noninvasively from oxygen uptake during exercise. J. Appl. Physiol. 82(3): 908–912, 1997.