1 INTRODUCTION Regular physical activity is widely recognised as a cornerstone of cardiovascular health, substantially reducing the risk of coronary heart disease, stroke and chronic heart failure (Lawler et al., 2011; Morris et al., 1953). Current guidelines recommend ≥150 min of moderate or ≥75 min of vigorous aerobic exercise per week for adults (Bull et al., 2020). However, an increasing number of individuals engage in high-volume intense endurance training, often exceeding 20 h weekly.