Effects of 8 Weeks' Training on Systemic and Muscle Oxygen Dynamics in University Rugby Players

The aim of this study was to investigate the effects of 8 weeks of training on O₂ dynamics in university rugby players. University rugby players (n = 15) participated in 5 strength training sessions and 4 field-based training sessions per week for 8 weeks. Before and after 8-weeks' training, the subjects performed ramp cycling exercise until exhaustion. Muscle O₂ saturation (SmO₂), relative changes from rest in deoxygenated hemoglobin concentration (∆Deoxy-Hb) and total hemoglobin concentration, cardiac output (CO), and pulmonary O₂ uptake (VO₂) were monitored continuously during exercise. Peak VO₂ and CO were normalized by fat-free mass. Though peak VO₂ tended to be increased after training, there were no significant changes in CO, nor any muscle O₂ dynamic variables at peak exercise between before and after training. However, an increase in peak VO₂ was significantly correlated with diminishment of deoxy-Hb and an increase in SmO₂. Changes in CO caused by training were not related to improved peak VO₂. The improvement of peak VO₂ during 8 weeks of rugby training may have been caused by muscle O₂ supply, rather than increased CO or muscle O₂ extraction.