However, they did not observe an improvement in VO2max after the same training program performed in hypoxia thenthereby conditions (typical IHT) and normoxia. In addition, the results of our last study (Czuba et al., 2011) allow us to conclude that IHT for three weeks (3 IHT sessions per week) with prolonged exercise (30�C40min) at lactate threshold is an effective training means for improving VO2max and endurance performance at sea-level. This results are in accordance to those obtained by Dufour et al. (2006) and Zoll et al. (2006), where subjects trained with very similar intensity (at the second ventilatory threshold) during IHT sessions for six weeks, but twice a week. A comparison of the results of these experiments (Dufour et al., 2006; Zoll et al., 2006; Czuba et al.

, 2011) with those obtained by the authors suggests that exercising during IHT at the anaerobic threshold intensity selected individually to match the designated altitude (hypoxia) effectively improves aerobic capacity and exercise performance. Similarly, Robertson et al. (2010) observed a significant improvement in values of VO2max after 3 weeks of IHT protocol (4 training sessions per week at 2,200 m). The IHT sessions incorporated one long, one moderate duration, and two interval sessions with high intensity per week. The specific content of these sessions was based on individual training programmes with athletes instructed to complete between 4 and 5 h of hypoxic training per week, depending on their normal training load. Unfortunately, the authors did not report more details about the duration of IHT sessions.

There is also strong evidence that demonstrated no beneficial effects of IHT programs on aerobic capacity, when the intensity during IHT sessions was set below 80% of VO2max at sea level (Vallier et al., 1996; Truijens et al., 2003; Ventura et al., 2005). The absence of positive adaptive changes in these athletes is very probable due to insufficient exercise intensity during the IHT protocol. The recent study on IHT that was carried out with triathletes placed in a hypobaric chamber (Hendriksen and Meeuwsen, 2003) also failed to demonstrate improvements in VO2max. Exercise intensity in that study was selected individually to correspond to 60�C70% of Heart Rate Reserve (HRR), so the subjects exercised in the aerobic exercise zone during a 10-day training period.

During the annual training cycles, such training units are used to maintain the Cilengitide athlete��s fitness level and not to improve it. The results of this study build on and enhance the earlier research into the IHT method. In the analysed basketball players, significantly higher VO2max (by 8%) and longer distance covered in the maximal ramp test were recorded after 3 weeks of high intensity interval training in normobaric hypoxia. In the group H where the IHT protocol was applied, the increase in VO2max was greater by 5% than in the group C that trained in normoxia.