Increased maximal oxygen uptake after sprint-interval training is mediated by central hemodynamic factors as determined by right heart catheterization

This study investigated the importance of maximal cardiac output (Qmax ) in relation to VO2max improvements following SIT and the relative importance of the hypervolemic response on Qmax and VO2max . We also investigated if systemic O2 extraction increased with SIT as has been previously suggested. Healthy men and women (n = 9) performed 6 weeks of SIT. State-of-the-art measurements: right heart catheterization, carbon monoxide rebreathing and respiratory gas exchange analysis were used to assess Qmax , arterial O2 content (ca O2 ), mixed venous O2 content (cv O2 ), blood volume (BV) and VO2max before and after the intervention. In order to assess the relative contribution of the hypervolemic response to the increases in VO2max , BV was reestablished to pre-training levels by phlebotomy. Following the intervention, VO2max , BV and Qmax increased by 11% (p<0.001), 5.4% (p = 0.013), and 8.8% (p = 0.004) respectively. cv O2 decreased by 12.4% (p = 0.011) and systemic O2 extraction increased by 4.0% (p = 0.009) during the same period, both variables were unaffected by phlebotomy (p = 0.589 and p = 0.548, respectively). After phlebotomy, VO2max and Qmax reverted back to pre-intervention values (p = 0.064 and p = 0.838 respectively) and were significantly lower compared to post-intervention (p = 0.016 and p = 0.018 respectively). The decline in VO2max after phlebotomy was linear to the amount of blood removed (p = 0.007, R = -0.82). The causal relationship between BV, Qmax and V...
Source: The Journal of Physiology - Category: Physiology Authors: Source Type: research