Current trends in altitude training

Recently, endurance athletes have used several novel approaches and modalit ies for altitude training including: (i) normobaric hypoxia via nitrogen di lution (hypoxic apartment); (ii) supplemental oxygen; (iii) hypoxic sleepin g devices; and (iv) intermittent hypoxic exposure (IHE). A normobaric hypoxic apartment simulates an altitude environment equivalent to approximately 2000 to 3000m (6560 to 9840ft). Athletes who use a hypoxi c apartment typically 'live and sleep high' in the hypoxic apartment for 8 to 18 hours a day, but complete their training at sea level, or approximate sea level conditions. Several studies suggest that using a hypoxic apartme nt in this manner produces beneficial changes in serum erythropoietin (EPO) levels, reticulocyte count and red blood cell (RBC) mass, which in turn ma y lead to improvements in postaltitude endurance performance. However, othe r studies failed to demonstrate significant changes in haematological indic es as a result of using a hypoxic apartment. These discrepancies may be cau sed by differences in methodology, the hypoxic stimulus that athletes were exposed to and/or the training status of the athletes. Supplemental oxygen is used to simulate either normoxic (sea level) or hype roxic conditions during high-intensity workouts at altitude. This method is a modification of the 'high-low' strategy, since athletes live in a natura l terrestrial altitude environment hut train at 'sea level' with the aid of supplemental oxygen. Limited data regarding the efficacy of hyperoxic trai ning suggests that high intensity workouts at moderate altitude (1860m/6100 ft) and endurance performance at sea level may be enhanced when supplementa l oxygen training is utilised at altitude over a duration of several weeks. Hypoxic sleeping devices include the Colorado Altitude Training (CAT) Hatch (TM) (hypobaric chamber) and Hypoxico Tent System(TM) (normobaric hypoxic s ystem), both of which are designed to allow athletes: to sleep high and tra in low. These devices simulate altitudes up to approximately 4575m/15 006ft and 4270m/14 005ft, respectively. Currently, no studies have been publishe d on the efficacy of these devices on RBC production, maximal oxygen uptake and/or performance in elite athletes. IHE is based on the assumption that brief exposures to hypoxia (1.5 to 2.0 hours) are sufficient to stimulate the release of EPO, and ultimately bring about an increase in RBC concentration. Athletes typically use IHE while a t rest, or in conjunction with a training session. Data regarding the effec t of IHE on haematological indices and athletic performance are minimal and inconclusive.