Ausdauertraining unter Hypoxie und Hyperoxie: Auswirkungen auf die Ausdauerleistungsfähigkeit, hämatologische Parameter und die Signaltransduktion im humanen Skelettmuskel

Problem: The manipulation of the oxygen content in the breath represents an approach to the modification of the endurance training. It has been shown, for example, that the reduction of the oxygen content (hypoxia: HY) in ambient air favors the adaptation of the endurance performance as a result of regular endurance training in HY. The increase in the oxygen content (hyperoxia: PER) often results in an acute increase in performance. The variation of the oxygen content and the duration of application of HY and PER as well as the intensity, type and duration of training loads in studies are diverse. Therefore, it is still not possible to compare the physiological adjustments in response to HY and PER considering the study design.
Aim: For the first time, this work should enable a direct comparison of the adaptations of endurance training under HY and PER. This includes the levels of endurance performance, hematology, the acid-base balance and aspects of signal transduction in human skeletal muscle.
Methods: 11 male subjects underwent unipedal endurance training in HY, PER and NOR in two training periods over four weeks each. In study 1, global physiological parameters of endurance capacity were determined via performance diagnostics before and after the training intervention. In studies 1 and 2, muscle biopsies were taken at different times and examined with regard to mitochondrial signaling (study 1) and mTOR-associated signaling (study 2). Study 3 examined the adjustment of haematological parameters using venous and capillary blood draws.
Results: Study 1: The application of HY leads to a significantly reduced training intensity while PER induces a tendency to increase the acute performance. Study 1 and 2: Despite a significantly reduced training intensity in HY, training in HY does not have a negative effect on the adaptation of global physiological parameters or mitochondrial and mTOR signaling. Study 3: PER leads to a potential reduction in erythrocyte parameters (MCH, [Hb], MCHC) after 4 weeks, while HY brings about an
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Summary of the doctoral thesis
improvement at this level. Training in PER reduces and in HY increases the acute pH value in the arterialized capillary blood.
Conclusion: This work allows for the first time a comparison between the acute and chronic training adjustments in response to training in HY and PER. It was shown that HY requires a reduction in acute performance, but thereby induces the same adaptations as training in PER which allows to increase training intensity compared to normoxia. This leads to a high practical relevance of HY in the clinical or rehabilitative setting in situations that require a reduction in musculoskeletal stress. PER, on the other hand, can increase the acute performance and thereby enable training in diseases of the cardiopulmonary system. In order to confirm these assumptions, the aim of future studies is to investigate patient collectives.