Exploring Sex-Based Effects in Wasted Pressure Effort and Subendocardial Viability Ratio Post-Maximal Exercise

Background: Maximal exercise testing assesses the body’s oxygen requirements during intense physical activity, and provides insights into cardiovascular and respiratory efficiency, not evident at rest. Late systolic augmentation of a reflected pressure wave causes an increase in left ventricular (LV) pressure, which contributes to increased myocardial oxygen demand. The additional effort the LV must exert does not contribute to blood ejection. Myocardial oxygen supply and demand is expressed as the subendocardial viability ratio (SEVR). Females tend to have higher amounts of wasted left ventricular effort (Ew), as well as a lower SEVR compared to men. The purpose of this study was to investigate if sex differences exist for Ew and SEVR following maximal exercise in healthy adults. Methods: Young healthy adults (42 f/31 m; 18-35 yrs) completed a VO2peak test on a cycle ergometer. Ew and SEVR were estimated from tonometry-derived radial artery pulse contour analysis at rest, 15, and 30-min post-exercise. Systolic and diastolic pressure time indexes (SPTI; DPTI) were calculated, which represents the pressure multiplied by the duration during the cardiac cycle. Results: Females had consistently higher Ew than males (d= 1010 dyne cm −2 s, 95% CI: 253 to 1534 dyne cm −2 s, p =.003) at all time points but not SEVR ( p = 0.748). After maximal exercise, Ew was similarly reduced in females and males, 15 and 30-min into recovery (difference (d)= -1350 dyne cm −2 s, 95% CI: -1793 to -875 dyne cm −2 s, p <0.001). Both sexes exhibited a reduction in SEVR 15-min post-exercise (d= -0.254, 95% CI: -0.447 to -0.123, p <0.001), followed by an increase above resting levels 30-min into recovery (d = 0.383, 95% CI: 0.217 to 0.543, p <0.001). Both SPTI and DPTI were reduced 15-min after exercise testing, but only DPTI contributed to the increase of SEVR, 30-min into recovery (d= 10483 mm Hgxms, 95%CI: 6954 to 14010 mm Hgxms, p <0.001). Controlling for VO 2 peak , body mass index, and heart rate did not change the above results. Conclusion: Maximal exercise testing caused a post-exercise decrease in Ew, in both males and females, mostly due to vasodilation. Further, SEVR increased similarly between sexes after 30 minutes, indicating an increase in cardiac perfusion. These data suggest there are no sex differences following maximal aerobic exercise. This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.