IntroductionThe use of hypoxic training to improve sports performance through enhancing aerobic and anaerobic metabolic path-ways has received much attention in recent years due to the good results obtained by athletes who born and live in altitude [1]. However, performance is significantly compromised when high intensity sport is achieved in hypoxia [2]. Although several studies have described thepositive effects of altitude exposure (chronic and inter-mittent) on aerobic [3,4] and anaerobic capacity [5—11]following different hypoxia protocols, other have failedto found these effects [12,13]. By this reason a scientific consensus on anaerobic training and performance follow-ing the use of hypoxia to improve sea level performance remain unclear. This can be due at least in part because of the large number of studies, which have employed different methodologies or measured different variables[