Intermittent hypoxic training for 6 weeks in 3000 m hypobaric hypoxia conditions enhances exercise economy and aerobic exercise performance in moderately trained swimmers

Abstract

Athletic endurance performance at sea level can be improved via intermittent hypoxic training (IHT). However, the efficacy of IHT for enhancement of aerobic exercise performance at sea level is controversial because of methodological differences. Therefore, the aim of the study was to determine whether the IHT regimen ameliorates exercise economy and aerobic exercise performance in moderately trained swimmers. A total of 20 moderately trained swimmers were equally assigned to the control group (n=10) training in normoxic conditions and the IHT group (n=10) training at a simulated altitude of 3000 m. They were evaluated for metabolic parameters and skeletal muscle oxygenation during 30 min submaximal exercise on a bicycle, and aerobic exercise performance before and after 6 weeks of training composed of aerobic continuous exercise set at 80% maximal heart rate (HRmax) during 30 min and anaerobic interval exercise set at the exercise load with 90% HRmax measured in pre-test during 30 min (10 times 2 min exercise and 1 min rest). According to the results, the IHT group demonstrated greater improvement in exercise economy due to decreases in VO2 (p=.016) and HHb (p=.002) and increases in O2Hb (p<.001) and TOI (p=.006). VCO2 was decreased in the IHT group (p=.010) and blood lactate level was decreased in the control (p=.005) and IHT groups (p=.001). All aerobic exercise performance including VO2max (p=.001) and the 400 m time trial (p<.001) were increased in the IHT group. The present findings indicate that the 6 week IHT regime composed of high-intensity aerobic continuous exercise and anaerobic interval exercise can be considered an effective altitude/hypoxic training method for improvement of exercise economy and aerobic exercise performance in moderately trained swimmers.

Interval Hypoxic Training Enhances Athletic Performance and Does Not Adversely Affect Immune Function in Middle- and Long-Distance Runners

“…Additionally, the paired t-test was used to compare between the post-and pre-training values of the dependent variables in each group separately. A priori power analysis was performed with G-power for the energy metabolic parameter (VO 2 during 30-min of submaximal exercise) based on previous research [1], indicating that a sample size of 14 participants (7 subjects per group) would be required to provide 80% power at an α-level of 0.05. We anticipated a dropout rate of >10% and aimed for a starting population of 20.…”

“…Hemodynamic function was measured before and after training while the participants performed submaximal cycle ergometer exercise corresponding to 80% HRmax obtained during the pre-test period for 30 min at sea level [1,11]. The oxygen uptake (VO 2 ) was measured using the K5 auto metabolism analyzer (Cosmed, Rome, Italy) and a breathing valve in the form of a facemask.…”

“…The oxygen transport capacity in systemic conditions is most often evaluated using VO 2 max [8]. Exercise training in a hypoxic condition may increase exercise performance by inducing various biochemical and structural adaptive changes in the skeletal and cardiac muscles, which favor the oxidative process and can enhance non-hematological parameters, such as exercise economy, acid-base balance, and metabolic response during submaximal exercise, ultimately leading to improved oxygen delivery and utilization capacity [1,[8][9][10][11]13]. Among the various LLTH methods, IHT consists of repeated exposures to 5-7 min of steady or progressive hypoxia, interrupted by equal periods of recovery; it can modify oxygen transport and energy utilization and induce permanent modifications in the cardiac function [12].…”

“…Endurance exercise performance is related to various factors that can be altered by diverse hypoxic training methods, including erythropoiesis, exercise economy, capillary density, hemodynamic function, and acid-base response in the skeletal muscle [1,2]. Enhancing these factors, which are related to endurance exercise performance, increases the efficiency of aerobic energy production and consequently enhances maximum oxygen uptake (VO 2 max).…”

“…The LHTH method involves living and training at 1500-4000 m in natural altitude environments, while the LHTL method involves living at or near sea level but training under a natural or simulated altitude condition of 2000-3000 m [3,4,6]. The LLTH method may be of particular interest to athletes because this training commonly involves shorter hypoxic exposure (approximately two to five sessions per week of <3 h), lower cost, lesser effort, and lesser time than the LHTH and LHTL methods [1]. Further, the LLTH method, includes interval hypoxic training (IHT), repeated sprint training in hypoxia, and resistance training in hypoxic conditions; it has become an increasingly popular altitude/hypoxic practice, where athletes live at or near sea level but train in 2000-4500 m simulated hypobaric or normobaric hypoxic conditions [9][10][11].…”