Identify two randomized controlled trials (RCTs) which have investigated the influence of altitude training on sports performance in endurance athletes.

Two randomized control trials (RCT) which have investigated the influence of altitude training on sport performance in endurance athletes are “Living High- Training Low effect of moderate- altitude acclimatization with low -altitude training on performance CITATION Lev97 l 2057 (Levine BD, 1997) and Effect of FIO2 on Physiological Responses and Cycling Performance at Moderate Altitude CITATION WILE7 l 2057 (WILBER, JULY 2003 ISSUE 7 ).
In CITATION Lev97 l 2057 (Levine BD, 1997), Thirty-nine competitive runners (27 men, 12 women) completed 1) a 2-week lead-in phase, followed by 2) 4 week of supervised training at sea level; and3) 4 week of field training camp randomized to three groups: “high-low” (n = 13), living at moderate altitude (2,500 m) and training at low altitude (1,250 m); “high-high” (n = 13), living and training at moderate altitude (2,500 m); or “low-low” (n= 13), living and training in a mountain environment at sea level (150 m). A 5,000-m time trial was the primary measure of performance; laboratory outcomes included maximal O2uptake (V?o2 max), anaerobic capacity (accumulated O2deficit), maximal steady state (MSS; ventilatory threshold), running economy, velocity at V?o2 max, and blood compartment volumes. 

In CITATION WILE7 l 2057 (WILBER, JULY 2003 ISSUE 7 ), Subjects (N = 19) were trained male cyclists who were permanent residents of moderate altitude (1800–1900 m). Testing was conducted at 1860 m (PB 610–612 Torr, PIO2 ?128 Torr). Subjects completed three randomized, single-blind trials in which they performed a standardized interval workout while inspiring a medical-grade gas with FIO2 0.21 (PIO2 ?128 Torr), FIO2 0.26 (PIO2 ?159 Torr), and FIO2 0.60 (PIO2 ?366 Torr). The standardized interval workout consisted of 6 × 100 kJ performed on a dynamically calibrated cycle ergometer at a self-selected workload and pedalling cadence with a work: recovery ratio of 1:1.5.

Discuss these two RCTs to illustrate whether altitude training is an efficacious method of improving sports performance in endurance athletes.
In CITATION Lev97 l 2057 (Levine BD, 1997), altitude training is very frequently used by professional athletes who compete at an elite level to improve seal level performance. In this research study it is seen that hypoxic exercise may increase the training stimulus, which magnifies the effects of endurance training however on the other hand hypoxia at altitude limits training intensity and may result in relative deconditioning. There were several phases regarding this study such as a sea level lead in phase which was essential in allowing the athlete to become familiar with laboratory testing procedures and as well to allow them to train for a supervised two-week period. This ensures that all the athletes are brought to an equivalent level of readiness. Next stage was the sea level training which provided a longitudinal sea level control of the study and it was conducted based on a 4 week mesocycle with the objective to increasing volume and intensity over a three week period and slightly taper in the last week\ Sequentially was the altitude training camp, seal level testing period an evaluation of performance compromised of track evaluation (5000m time trial), treadmill evaluation(vO2 max), maximal steady rate (MSS) and anaerobic capacity and submaximal running economy and performance.
In terms of training there was no significant change in sea level training by any criteria amongst the groups. In regard to Blood Compartment Volumes, the plasma volume increased in the high-low groups by training at sea level in the heat and it decreased back to baseline after training in the cooler mountain environments. In the sea level group plasma volume remained unchanged. Athletes did not increase in V0z max in any group because a plateau had been reached in aerobic power due to the training programme at seal level. Like the vOz max, MSS did not change in any group after the sea level training the only group that a change occurred in was in the high low group after the altitude training camp and neither did a change occur as well in anaerobic capacity. After training at seal level or altitude, the uphill treadmill time remained constant across the groups. Only in the field training time, was there a change and it was in the uphill treadmill run time of the high high group.
In CITATION WILE7 l 2057 (WILBER, JULY 2003 ISSUE 7 ), there was some pre-experimental testing conducted such as body composition in terms of lean body mass and percentage body fat, power output at blood lactate threshold, maximal oxygen uptake and power at O2 max. Also, as well the subjects were able to complete a habituation trail that stimulated the experimental exercise wearing the experimental equipment. The tests were undertaken under three conditions of  1) FIO2 0.21 (PB 610–612 Torr, PIO2 ?128 Torr), which served as the control/placebo trial; 2) FIO2 0.26, which at the elevation of our laboratory (1860 m, PB 610–612 Torr) yielded a PIO2 roughly equivalent to normoxia/sea level (?159 Torr); and 3) FIO2 0.60, which served as a hyperoxic trial (PB 610–612 Torr, PIO2 ?366 Torr). The subjects were evaluated on various dependent variables during the experimental trials. The results obtained during the trials show that the use of supplemental oxygen during high intensity interval work out by trained cyclists at moderate altitude resulted in significant increases in oxyhaemoglobin saturation and in average power output which in turn contributed an increase in exercise performance. The study also proved that F1O2 has minimal effect on heart rate and stroke volume.
To conclude both studies show that altitude training is an efficacious method of improving sports performance in endurance athletes.
BIBLIOGRAPHY Levine BD, S. G. (1997). “Living high- Training Low” effect of moderste-altitude acclimatization with low -altitude training on perfomance . Journal of Applied Physiology , 102-112.

WILBER, R. H. (JULY 2003 ISSUE 7 ). Effects of F102 ON PHYSIOLOLGICAL REPSONSES AND CYCLING PERFORMANCE AT MODERATE ALTITUDE . Medicine&Science in Sports& Exercise , 1153-1159.

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