Scientific Programme
Physiology & Nutrition
IS-PN06 - Sex Differences in Hemodynamics and Oxygen Transport during Maximal, Supramaximal, and Time-Trial Exercises: Insights from Normalization Strategies and Thermodilution Measurements
Date: 03.07.2025, Time: 17:00 - 18:15, Session Room: Castello 2
Description
Understanding sex differences in exercise physiology is crucial for optimizing athletic performance and health. Males and females differ in body size, cardiovascular structure, and -function, influencing oxygen transport and utilization during exercise. This symposium provides advanced insights into the physiological mechanisms driving these differences. The first presentation examines the limiting factors to maximal oxygen uptake (VO₂max) and time-trial performance, emphasizing sex-specific differences in cardiac output, leg blood flow, and oxygen extraction, while accounting for muscle mass normalization. The second presentation explores sex differences in functional reserve and supramaximal exercise performance, focusing on hemodynamic and oxygen transport responses and adaptive changes following sprint interval training combined with ischemia-reperfusion. The third presentation investigates sex differences in VO₂max after normalizing the oxygen transport capacity through blood withdrawal and carbon monoxide inhalation, with particular emphasis on echocardiographic assessments under altered hemodynamic loads. This symposium addresses critical gaps in understanding sex differences in performance and adaptive response, appealing to exercise physiologists, sports scientists, clinicians, and professionals working with athletes.
Chair(s)
Øyvind Skattebo
Norwegian School of Sport Sciences, Department of Physical Performance
Norway
Speaker A
Øyvind Skattebo
Norwegian School of Sport Sciences, Department of Physical Performance
Norway
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Sex Differences in Cardiac Output, Leg Blood Flow, and Oxygen Extraction at VO₂max and During Time-Trial Exercise: Insights from Thermodilution-Based Measurements
Historically, most exercise physiology research has been conducted on males, with findings often generalized to females. However, females and males have distinct body sizes and compositions, and their cardiovascular system is scaled differently, which may impact the applicability of these results. Recent studies suggest that males and females differ in central and peripheral factors limiting maximal oxygen uptake (VO₂max), yet much remains unknown about the mechanisms behind these potential differences and their implications for performance. Understanding sex-specific differences in the cardiovascular system and the oxygen transport chain from the lungs to the muscles is critical for advancing our knowledge of sex differences in athletic performance. This lecture will present insights from cutting-edge research utilizing gold-standard catheter-based techniques, including thermodilution for precise assessment of cardiac output, stroke volume, and leg blood flow during exercise, as well as direct measurements of peripheral oxygen extraction. These methods offer the highest precision in assessing the physiological limits to VO₂max, allowing for an in-depth comparison of the oxygen transport chain between males and females. Data from submaximal, maximal, and time-trial exercise conditions will be presented, with a special focus on how closely the maximal hemodynamic responses observed at VO₂max are sustained during prolonged, competition-like exercises (time trials). Furthermore, the lecture will address the impact of normalizing hemodynamic variables, given that males and females differ substantially in muscle mass—the primary tissue consuming oxygen during exercise. This symposium will appeal to exercise physiologists, sports scientists, clinicians, and professionals working with female athletes, providing a comprehensive view of the mechanisms underlying sex-specific performance differences.
Speaker B
Marcos Martin-Rincon
University of Las Palmas de Gran Canaria, Department of Physical Education
Spain
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Sex differences in functional reserve: focus on hemodynamics and oxygen transport
Understanding the limits of human performance requires examining the concept of “functional reserve,” defined as the capacity to sustain or generate additional power even at the point of exhaustion. Research on how males and females utilize this reserve during high-intensity exercise remains limited, leaving critical gaps in our understanding of the underlying mechanisms. While recent evidence suggests that physiological responses to supramaximal exercise are broadly similar between sexes when normalized for lean mass, key questions remain about the compensatory mechanisms that could offset the presumed lower anaerobic capacity in women and the superior oxygen extraction observed in females during supramaximal exercise. This presentation will characterize the hemodynamic and oxygen transport responses to repeated bouts of supramaximal exercise in men and women, exploring how sprint interval training (SIT), with or without ischemia-reperfusion episodes at exhaustion, influences the functional reserve. We will focus on hemodynamics, oxygen delivery, and muscle blood flow using state-of-the-art invasive techniques, including thermodilution for measuring cardiac output, stroke volume, and leg blood flow, as well as peripheral muscle oxygen extraction. The lecture will explore whether SIT can modify the functional reserve differently in males and females and whether the application of ischemia-reperfusion immediately post-exercise may further enhance training adaptations. Additionally, we will investigate the potential of ischemia-reperfusion as a strategy to optimize hemodynamic responses and oxygen extraction during high-intensity efforts. By examining these factors, we aim to determine if targeted interventions can enhance the functional reserve and extend performance capacity. These findings will provide exercise physiologists, sports scientists, and health professionals with a deeper understanding of how training protocols can be optimized to leverage sex-specific adaptations, potentially informing strategies to enhance both performance and recovery in male and female athletes.
Speaker C
Candela Diaz-Canestro
University of Zurich, Center for Molecular Cardiology
Switzerland
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Sex differences in VO₂max after normalizing blood volume and O₂ carrying capacity
Maximal oxygen consumption (VO2max), a hallmark of aerobic capacity, is associated with large mortality reductions as well as cardiometabolic benefits. Understanding the physiological determinants of sex-differences on VO2max is a fundamental topic in exercise physiology that may have a crucial impact in the prevention of cardiovascular and metabolic diseases. Intrinsic sex differences in fundamental blood attributes have long been hypothesized to contribute to the gap in cardiorespiratory fitness between men and women. The aim of the present study was to understand whether sex differences in VO2max can be explained by blood volume and effective hemoglobin. This lecture will present insights from state-of-the-art methods for blood normalization by using blood withdrawal and O2 carrying capacity reduction via carbon monoxide rebreathing as well as exercise echocardiography inside a lower body negative pressure chamber (to induce hemodynamic loads characteristic of the upright position). We will present data on pulmonary, cardiac and hemodynamic variables from rest to peak incremental exercise as well as at a fixed submaximal workload in women and men prior to and after blood normalization. This symposium will address a relevant knowledge gap in our basic comprehension of cardiovascular physiology that may appeal to a broad audience including exercise physiologists, sports professionals and clinicians.