Blood Volume and Vascular Diversity in Highly Endurance Trained Athletes: Sport Specificity? - A Cross-sectional Study

Background: Blood volume (BV) is a critical component for cardiac output. However, it is unknown to what extent a high BV contributes to explain differences in maximal oxygen uptakes(VO2max) in elite athletes in different sports. Furthermore, efficient oxygen delivery to working skeletal muscles challengesthe vascular system, and arterial changes are found in athletes disposed to chronic endurance training. Whether these arterial changes influence the arterial dilatory response in endurance athletes with different involvements of the upper, lower and whole body is unclear. Objective:The aims of this study were to compareVO2max, BV, hemoglobin mass (Hbmass) and vascular function in highly trained endurance athletes primarilyusing whole (cross-country skiing), lower (orienteering) and upper body (flatwater kayak). Method: 43 male endurance athletes in the disciplines of cross-country skiing (n=17), orienteering (n=15) and flatwater kayak (n=11) participated in a cross-sectional study. VO2max was measured using direct ergospirometry, carbon monoxide re-breathing method was used to assess BV variables and endothelial function was measured as flow mediated dilatation (FMD). Results: The cross-country skiers had higher VO2max than the orienteers regarding mL⋅min-1 ⋅kg -1 and L⋅min-1 (p<0.01). The cross-country skiers and orienteers showed significantly higher BV than the kayakers, both relative to body mass (p<0.05) and FFM (p<0.01). The cross-country skiers had significantly higher Hbmassthan the kayakers relative to body mass and fat free mass (p<0.05), with no significant differences between the crosscountry skiers and orienteers. The kayakers presented significantly larger arterial diameter than the orienteers (p