# The Effects of Intermittent Hypoxic Training on Anaerobic Performance in Young Men
## 1 Introduction  
Hypoxic training is considered one of the training methods that can effectively improve sea-level performance. This training method is becoming increasingly popular among elite athletes [1]. Several hypoxic training models are used in practice, and their effectiveness is constantly being verified and their training methods optimized [2]. The effects of hypoxic training on aerobic endurance are well described [3; 4], and the reason for the improvement in aerobic capacity (endurance performance) is primarily attributed to improvements in hematological indices, i.e., an increase in erythrocyte count, blood hemoglobin concentration or blood oxygen capacity [2]. Training in hypoxia also produces beneficial non-hematological effects such as increased skeletal muscle mitochondrial density and fiber cross-sectional area, or an improved capillary-to-fiber ratio [4; 5], enhanced glycolysis [6] and improved buffering capacity [7]. These reported non-hematological effects of training in hypoxia suggest that hypoxic training may also be effective in improving anaerobic performance. Previous studies on the effects of hypoxic training on anaerobic capacity are scarce (compared to the number of studies on the effects of hypoxia on endurance performance) [1], and the data presented are inconclusive, and often contradictory. Previous studies have reported both improvements in peak power [8; 9], and no effect of training in hypoxia on anaerobic performance [1; 10]. The ambiguity in the effectiveness of training in hypoxia is usually explained by the use of different hypoxic training models, participant inclusion criteria, or the 'dose' of hypoxia [4]. One of the more currently popular training methods is intermittent hypoxic training (IHT), whereby the athlete only trainsunder hypoxia (usually a few tens of minutes) and lives in normoxia. The advantage of this method is that it does not interfere with athletes' lifestyle, sleep and post-exercise recovery, and that it is relatively low cost [11; 12]. This form of training (IHT) is classified as part of the 'Live Low-Train High' training model.  
Many sports are combined (aerobic and anaerobic) in nature, so hypoxic training may prove to be a universal training method used to improve not only aerobic but also anaerobic capacity [13; 14; 15]. Typical anaerobic efforts rely on the alactic energy system (ATP and phosphocreatine (PCr)) (up to 8-10 s of supramaximal exercise) and/or the lactic (glycolytic) energy system (usually 20-90 s of supramaximal exercise) [16]. In analyzing an anaerobic effort of supramaximal intensity lasting several tens of seconds, a number of phases can be distinguished in it, which finally determine the sports result in competition. In an ideal effort, after starting the effort from a stationary start, the athlete must reach maximal power as quickly as possible (short time to reach maximal power), and the maximal power itself must be as high as possible, determining the anaerobic alactic performance [17]. Once maximal power is reached, as the exercise progresses, the key is to maintain maximal power for as long as possible and to have the smallest possible power decrease per second of exercise. A small drop in the power and fatigue rate indicate a high efficiency of the glycolytic energy system and good anaerobic endurance [17]. During such an effort, the athlete should perform as much work as possible, and the average power from the entire effort should also be high. Thus, there are a number of parameters that characterize anaerobic performance, and have practical applications in sports training. These parameters are relatively rarely reported, and the authors of previous papers [1; 9] have focused only on maximal or mean power. The purpose of this study was to comprehensively determine the effects of IHT on anaerobic performance in young healthy men. We hypothesized that IHT can significantly improve both their peak and mean power.